ALL BIOLOGY APART FROM 3
Define depolarisation
A loss of the difference in charge between the inside and outside of the plasma membrane
Define ectotherm
Animals that use their surroundings to warm their bodies so their core temperature is heavily dependent on the environment
Define vaccination
The administering of a vaccine causing immunisation
Define the term intracellular enzymes
Enzymes inside cells Catalase
Define species
The smallest and most specific taxonomic group
what is adhesion
where water molecules are attracted to other materials
the whole sample is illmunated at once =
wide-field microscopy
how genes in the thorax control development of ...
wings, limbs and ribs
Suggest the functions of B-galactosidase and lactose permease synthesised by the lac operon
β-galactosidase catalyses the hydrolysis of lactose to galactose and lactose lactose permease enables the entry of lactose into cells
Define the term inspiration
Taking air in or inhalation- energy using process
State the general formula of carbohydrates.
(CH2O)x where x is any number between 3 and 8
Proteins- building blocks
Amino acids
Define hypoglycaemia
Deficiency of glucose in the bloodstream
Proteins- name of dimer
Dipeptide
Proteins- name of macromolecule
Polypeptide
all animals are
segmented
Identify the stage of meiosis a cell is in from diagrams and photos of cells.
---
Examples of whole specimens prepared using a dry mount:
-hair -pollen -dust -insect parts
Draw a table to summarise the products of glycolysis, the link reaction and the Krebs cycle for one molecules of glucose.
1. 10 x reduced NAD 2. 2 x FADH2 3. 4 x ATP 4. 6 x CO2
Describe how the epidermis of plants is specialised for its function
1. A single layer of closely packed cells covering the surface of plants 2. Usually covered by a waxy waterproof cuticle- reduces loss of water 3. Stomata are present in the epidermis- allow exchange of gases
What is returned to the light dependent reaction from the Calvin Cycle
1. ADP + P 2. NADP
Explain why B lymphocytes are called "B" whereas T lymphocytes are called "T".
1. B lymphocytes mature in the Bone marrow 2. T lymphocytes mature in the Thymus gland
Explain why multicellular organisms need a communication system.
1. Cells within organisms have become specialised to perform specific functions 2. Organisms need to coordinate the function of different cells and systems to operate effectively and respond to changes 3. Few body systems can work alone
Define plant hormone
1. Chemical signals to coordinate growth and responses 2. They do not always act in the same way as animal hormones
State the names of the anatomical layers in capillaries
1. Contain an endothelial layer.
Identify the components of the pancreas in a photomicrograph of a stained section.
1. Dark pink surroundings is the pancreatic acini 2. Light pink big circle in the middle of pancreatic acini is the islet of Langerhan
Describe how molecules move across the dialysis membrane
1. Diffusion down a concentration gradient 2. No active transport
Describe the role of B effector cells
1. Divide to form plasma cell clones
State the properties and functions of glucose
1. Glucose is a hexose sugar and can either be alpha or beta glucose which both have a ring structure. 2. It's structure makes it soluble so it can be easily transported - because hydrogen bonds from between the hydroxyl groups and water molecules 3. And its chemical bonds contain a lot of energy 4. this relates to its function as the main energy source in animals and plants 5. It is polar so hydrogen bonds can form.
Describe the evidence used to create the "Three Domain System" of classification
1. Groups organisms using differences in the sequences of nucleotides in the cells' ribosomal RNA 2. the cells' membrane lipid structure and their sensitivity to antibiotics 4. Scientists can discover evolutionary relationships between organisms by comparing DNA and protein structure.
Explain how to calculate the percentage error of a measurement (and when data are combined e.g. to obtain data on the change of a particular value over time).
1. Have the absolute uncertainty (e.g +- 0.5) 2. divide it by the amount measured (e.g 100) 3. multiply by 100 4. if measuring the change in something or have two measurements you add the uncertainties together.
State all the interactions that occur in tertiary structure
1. Hydrophobic and Hydrophillic interactions 2. Hydrogen bonds 3. Ionic bonds 4. Disulfide bonds
List the stages of the cell cycle in order and outline what happens at each stage.
1. Interphase- Period of cell growth and DNA replication 2. Mitotic phase- mitosis and cytokenisis (cytoplasmic division) 3. G0- where the cell leaves the cycle either temporarily or permanently
Describe 5 ways in which antigens can be obtained for use in vaccines.
1. Isolated antigens 2. Genetically engineered antigens 3. Killed or inactive pathogens 4. Weakened (attenuated) pathogens 5. Altered toxins
Why can lactate fermentation not occur indefinitely .
1. It cannot occur indefinitely because the reduced quantity of ATP produced would not be enough to maintain vital processes for a long period of time 2. The accumulation of lactic acid causes a fall in pH leading to proteins denaturing. Respiratory enzymes and muscle filaments are made from proteins and will cease to function at low pH.
Describe the structure and location of the medulla oblongata
1. It contains many important regulatory centres of the autonomic nervous system 2. These control relex activities such as ventilation (breathing rate) and heart rate 3. It also controls activities such as swallowing, peristalsis and coughing
Define electron transport chain
1. It is made up of a series of electron carriers each with progressively lower energy levels. 2. As high energy electrons move from one carrier in the chain to another, energy is released.
State 5 factors that affect the rate of photosynthesis.
1. Light intensity 2. Carbon dioxide concentration 3. Temperature 4. Water 5. pH 6. Mineral ions
Describe the role of T memory cells
1. Live for long time as part of immunological memory 2. If they meet an antigen for the second time they divide rapidly to form a huge number of clones of T killer cells that destroy the pathogen
Describe the structure of the sodium channels on the post synaptic membrane.
1. Made up of 5 proteins sub-units 2. Has receptor sites where the neurotransmitter binds to
What are 4 different types of receptor
1. Mechanoreceptor 2. Chemoreceptors 3. Thermoreceptors 4. Photoreceptors
Explain how the hydrostatic pressure of the blood drops as the blood moves away from the heart
1. More smaller vessels which have a larger cross-sectional area 2. Reduced resistance to blood flow 3. The arteries stretch and expand 4. Loss of fluid from the capillaries
Describe the idea of synergism and antagonism
1. Most plant hormones do not work on their own but by interacting with other substances- very fine control can be achieved 2. If different hormones work together, complementing each other and giving a greater response then they would on their own, the interaction is known as synergism 3. If the substances have opposite effects- one promoting growth and one inhibiting it, the balance between them will determine the response of the plant- antagonism
State the molecules required for the Krebs cycle
1. NAD 2. FAD 3. ADP + P 4. Acetyl CoA to deliver acetyl group 5. Oxaloacetate
Show the chemical symbol and biological processes Hydroxide ions are responsible for
1. OH- 2. Affects the pH of substances 3. Catalyses reactions.
Explain the benefit of having 2 lenses in a microscope
1. Objective lens and eyepiece lens 2. objective lens magnifies the specimen 3. eyepiece lens magnifies image (from objective lens) 4. higher magnification (produced than with just one lens)
Show the chemical symbol and biological processes Phosphate ions are responsible for
1. PO4 3- 2. Involved in photosynthesis and respiration reactions. 3. Needed for cell membrane formation 4. Needed for nucleic acid and ATP formation 5. Needed for bone formation- calcium phosphate
Define the term pheromone
1. Pheromone is a chemical made by an organism which affects the social behaviour of other members of the same species 2. Because plants do not behave socially they do not rely a lot on pheromones, but they do use them to defend themselves sometimes
Name the 3 main types of B lymphocytes
1. Plasma cells 2. B effector cells 3. B Memory cells
List the functions of cholesterol
1. Plays a part in producing hormones for cell communications 2. also produce vitamins like vitamin D - fat soluble
List the stages of mitosis in order.
1. Prophase 2. Metaphase 3. Anaphase 4. Telophase 5. (cytokenisis)
Describe how the components of urine may be affected by if the kidneys are infected or affected by high blood pressure
1. Proteins in the urine- if the basement membranes or podocytes of the Bowman's capsule are damaged, they can no longer acts as filters and large plasma proteins can pass into the filtrate and are passed out in the urine 2. Blood in the urine- another symptom that the filtering process is no longer working
Explain the differences between the pulmonary and systemic circulations.
1. Pulmonary circulation refers to the circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned to back to the heart. Pulmonary circulation only occurs between the heart and the lungs. 2. Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body
Describe the functions of the kidney
1. Removing waste products from the blood 2. Osmoregulation
Describe the characteristic abilities of stem cells as compared to specialised cells.
1. Stems cells begin as undifferentiated cells and originate from meiosis or mitosis 2. They are unspecialised and have the potential to become any one of a range of specialised cell types in an organism 3. They are the source of new cells necessary for growth, development and tissue repair.
Define quantitative test
1. Tell you the amount that is present in the sample
Define the term transamination
1. The conversion of one amino acid into another 2. This is important because the diet does not always contain the right balance of amino acids but transamination can over come the problems this might cause
Define proximal convoluted tubule
1. The first coiled region of nephron after the Bowman's capsule, found in the cortex of the kidney 2. This is where many of the substances needed by the body are reabsorbed into the blood
What factor other than pressure and pH affects heart rate and how does this affect it
1. The presence of hormones 2. In times of stress adrenaline and noradrenaline are released 3. These hormones affect the pacemaker region of the heart itself- they speed up your heart rate by increasing the frequency of impulses produced by the SAN
Describe the process of cyclic photophosphorylation
1. The same as non-cyclic 2. But the electrons leave the electron transport chain after PS1 are returned to PS1 instead of being used to form reduced NADP. 3. This means PS1 can still lead to the production of ATP without any electrons being supplied from PS2
Describe the adaptations of the insect gas exchange system that make it an efficient exchange surface.
1. The tracheoles provide a large SA for gas exchange 2. The tubes are thin- allows the tracheoles to go close to cells- minimise diffusion distance
Define dendron
1. These are short extensions which come from the cell body 2. These extensions divide into smaller branches called dendrites 3. They are responsible for transmitting electrical impulses towards the cell body
Describe the function of valves in veins and explain how they work.
1. They are flaps or infoldings of the inner lining of the vein 2. When blood flows in the direction of the heart the valves open so the blood can pass through 3. If the blood starts to flow backwards the valves close to prevent this from happening
Describe two ways in which stem cells may be useful in research.
1. They can divide indefinitely and differentiate into almost any cell within an organism
Describe the function of adrenaline
1. This increases the heart rate sending blood quickly to the muscles and brain 2. It also rapidly raises blood glucose concentration levels by converting glycogen to glucose in the liver
Define spatial summation
1. This occurs when a number of presynaptic neurones connect to one postsynaptic neurone 2. Each releases neurotransmitter which builds up to a high enough level in the synapse to trigger an action potential in the single postsynaptic neurone
List 7 physical defences plants have against herbivory.
1. Thorns 2. Barbs 3. Spikes 4. Spiny leaves 5. Fibrous and inedible tissue 6. Hairy leaves 7. Stings
Define the term "intrinsic protein"
1. Transmembrane proteins are embedded through both layers of a membrane e.g channel and carrier proteins 2. They have amino acids with hydrophobic R-groups on their external surfaces, which interact with the hydrophobic core of the membrane keeping them in place
State the function of the xylem
1. Transport of water and mineral ions 2. Support
Describe how alkaloids help protect plants from herbivory
1. Very bitter tasting nitrogenous compounds found in many plants 2. Many affect the metabolism of animals that take them in and sometimes poisoning them 3. Include caffeine, nicotine, morphine and cocaine 4. Caffeine is toxic to fungi and insects, the caffeine produced by coffee bush seedlings spreads through the soil and prevents germination of the seeds of other plants
Explain why it is important to keep conditions inside cells relatively constant.
1. Vital for cells to function normally and to stop them being damaged 2. e.g. Enzymes denatured 3. Glucose in blood needs to be controlled so there is always enough for respiration
State 3 ways most plants conserve water or gain better access to water.
1. Waxy cuticle- reduce transpiration from the leaf surfaces 2. Stomata are mainly found on the underside of the leaf and can be closed to prevent water loos 3. Roots grow down to the water in the soil
Draw a table to compare meiosis I, meiosis II and mitosis.
1. What lines up in the middle of the cell- M1-bivalents, M2- chromosomes, M-Chromosomes 2. Crossing over? Only in M1 3. Daughter cell number- M1-2, M2-4, M-2 4. Homologous pairs- Only in M1 5. DNA duplicated- In M1 and M during interphase 6. Diploid or haploid- M1- Hap, M2- Hap, M- Dip 7. Independent assortment- In M1 and M2
State 3 characteristics which are solely genetically determined
1. blood group 2. eye colour 3. shape of ear lobes
Name the 4 mechanisms that can affect the transcription of genes
1. chromatin remodelling 2. histone modification 3. lac operon 4. role of cyclic AMP
Explain how to use a stage micrometer and eye-piece graticule to add a scale bar to a drawing.
1. measure the specimen with the eyepiece graticule. 2. then multiply it by the magnification factor 3. this will get the size of the specimen in micrometres 4. draw specimen and put a bar underneath.
Name the 2 mechanisms involved in post-transcriptional/pre-translational control
1. rna processing 2. rna editing
Identify the host species of, and the type of pathogen causing, the following disease tobacco mosaic virus
1Host- plants (tobacco plants especially) Virus
State how many amino acids occur in life.
20
prokaryotic ribosomes
70s
Eukaryotic Ribosomes
80s
Define the term "turgid",
A cell which is swollen by water
Define population
A group of organisms of one species that live in the same place at the same time
Define the term tropism
A growth response by a plant in response to a unidirectional stimulus
Define the term macromolecule
A large complex molecule with a large molecular mass e.g a protein or a lipid
Define the terms "competitive inhibitor"
A molecule with a similar shape to that of a substrate, so it competes with the substrate to bind to the enzyme's active site.
Define the term coenzyme
A non-protein compound that is necessary for the functioning of an enzyme.- an organic cofactor They are changed in the reactions- act as a second substrate. Act as carriers moving in chemical groups between different enzymes.
Define the term bradycardia
A slow heart rhythm of below 60 beats per minute
Define totipotent
A stem cell that can differentiate into any type of cell and form a whole organisms
Define the terms "solute"
A substance dissolved in a solvent to form a solution
Define the terms "solution".
A substance formed from a solute dissolved in a solvent
Define the term substrate
A substance used or acted on, by another process or substance. For example a reactant in an enzyme-catalysed reaction.
Define cholinergic synapse
A synapse is cholinergic if it uses acetylcholine as its neurotransmitter
Define the test statistic
A test statistic is a standardized value that is calculated from sample data during a hypothesis test
State the transmission methods for the following animal diseases: tuberculosis, bacterial meningitis, AIDS, Influenza, Malaria, Ring worm, Athlete's foot. (F)
AIDS- inoculation, through a break of skin Athlete's foot- fomites TB/ Influenza- droplet infection- saliva and mucus from snezing, talking, coughing etc Malaria- Vector- mosquito
Explain how the polar nature of water makes it adhesive
Adhesion is the attraction between water molecules and the molecules of another substance. this is because it forms hydrogen bonds to other polar molecules
Define Ecosystem
All interacting living organisms and the non living conditions in an area
List 4 different types of organism that are ectotherms.
All invertebrate animals along with fish, amphibians, and reptiles
Define the term atrial fibrilation
An abnormal rhythm of the heart when the atria beat very fast and incompletely
What is in Benedict's reagent
An alkaline solution of Copper 2 sulfate
Define the term apoenzyme
An apoenzyme is an inactive enzyme, activation of the enzyme occurs upon binding of an organic or inorganic cofactor. It is the name of a precursor enzyme before a cofactor is added
Define hyperglycaemia
An excess of glucose in the bloodstream, it is a common effect of uncontrolled diabetes
Define the term zymogens
An inactive substance which is converted into an enzyme when activated by another enzyme.
Define undifferentiated
An unspecialised cell originating from mitosis or meiosis
Describe and explain the results you would expect to see from an experiment to investigate the effects of solutions of different water potential on plant and animal cells.
Animal cell- lower concentration means bigger percentage mass gain Plant cell- cylinders will gain water in solutions with a higher water potential.
Describe how the level of activity of an organism is related to demand for oxygen and glucose.
As the level of activity increases the more need for oxygen and glucose- respiration
Describe how diffusion distance, SA, Volume and SA:Vol ratio vary with increasing organism size.
As the organism increases in size so does the diffusion distance, SA and Volume. The SA:Vol is smaller as the volume increases more than SA
Explain why the chloride ion necessary for the correct formation of the active site in amylase is called a cofactor not a coenzyme or prosthetic group.
Because it is inorganic so can't be a coenzyme and is not a permanent feature of the protein.
Explain why the regeneration of NAD is the crucial part of either form of fermentation.
Because that is the thing that is needed for glycolysis
Explain why water loss is inevitable for plants.
Because the stoma must open to exchange oxygen and carbon dioxide, and water vapour is also lost by diffusion
The effects of adhesion and cohesion result in water exhibiting
CAPILLARY ACTION
Write a reversible set of equations to show the production of hydrogen carbonate ions.
CO2 ⇌ H2CO3 ⇌ H+ + HCO3-
Define point mutation
Changes one base in the triplet codon-may or may not have damaging effects
Define the term bundle of His
Conducting tissue composed of purkyne fibres that passes through the septum of the heart
What is differential staining?
Differential staining can distinguish between two types of organisms that would otherwise be hard to identify. It can also differentiate between different organelles of a single organism within a tissue sample
Define the term communicable disease
Diseases that can be passed from one organism to another of the same or different species
Define inorganic
Doesn't contain carbon
Lipids- the name of the reaction that joins the building blocks together
Esterification
Draw diagrams of a typical plant and animal cell, labelling the structures
Find a labelling activity online
Describe what happens during the G2 stage of interphase
G2 - Second growth phase - the cell continues to increase in size, energy stores are increased and the duplicated DNA is checked for errors.
Define gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. - often proteins
Draw, label and annotate a diagram of a generalised virus.
Genetic material surrounded by protein coat
Draw and label a diagram of ATP
Has 3 phosphate groups, the base adenine and ribose. ATP (adenosine triphosphate)
Identify the host species of, and the type of pathogen causing, the following disease malaria
Host- animals including humans Protoctist
State the site of glycolysis within cells.
In the cytoplasm of the cell
Define the terms "net movement of water".
Overall movement of water from one area to another.
Name the 3 kingdoms which all have very similar homeobox genes
Plants, animals and fungi
Define the term decarboxylation
Removal of carbon dioxide
Define the term oxidative decarboxylation
Removal of carbon dioxide along with hydrogen
Define the term spindle fibres
Spindle fibres form a protein structure that divides the genetic material in a cell.
Define abscission
The fall of leaves
Define lumen
The hole in the centre of the blood vessel
Define presynaptic membrane
The membrane of the neurone along which the impulse has arrived
Define postsynaptic membrane
The membrane of the neurone that receives the neurotransmitter
Define threshold potential
The membrane voltage that must be reached in an excitable cell during depolarisation in order to generate an action potential
Define the term translation
The process by which the complementary code carried by mRNA is decoded by tRNA into a sequence of amino acids. Occurs at a ribosome.
Define the terms "plasmolysis"
The pulling away of the cytoplasm and plasma membrane from the cell wall due to lack of water
Define the term "haemolysis".
The rupture or disruption of red blood cells
Define universal
The same specific base triplets code for the same amino acids in all living things. e.g UAU codes for tyrosine in all organism
Define stem cell
Undifferentiated cells with the potential to differentiate into a variety of the specialised cell types of the organism
What is the homeobox?
a section of DNA 180bp long coding for a part of the protein 60 amino acids long that is highly conserved (very similar) in plants, animals and fungi.
SER
is resposible for lipid and carbohydrate synthesis and storage
Define the terms "resolution"
is the smallest change in quantity being measured that can be detected by an instrument.
compare cytoskeleton in prokaryotes and eukaryotes
prokaryotic = present eukaryotic = present and more complex
compare ribosomes in prokaryotes and eukaryotes
prokaryotic = smaller 70s eukaryotic = larger 80s
mounting =
the specimens are then secured to a microscope slide and a sover slip placed on top
What is the function of relay neurones?
these neurones transmit impulses between neurones
many of the products of metabolism are =
toxic (so if they were allowed to build up in the body they would cause damage)
many of the stains are...
toxic or irritants
what do homeotic genes code for?
transcription factors
Explain the biological significance having a HSHC
Having an HSFC means a large quantity of energy to raise the temp by 1 degrees. so water temp is fairly stable reducing fluctuations in organisms and environments, cells and aquatic environments slow to freeze
Which nervous system is heart rate controlled by
Heart rate is involuntary and controlled by the autonomic nervous system
Define standard deviation
How spread out the data is. The greater the deviation the greater the spread of data
Describe two ways in which the heart's action changes in order to supply more oxygen and glucose to cells
Increase frequency of impulses sent by the sympathetic nervous
Define the the term breathing rate
Is the number of breaths taken per minute
Define the terms irreversible inhibitor
It binds permanently to an enzyme.
Suggest the importance of the creation of different allele combinations in populations.
It produces genetic variation so it allows species to adapt to changes in their environment. It makes gametes by halving the number of chromosomes. This means that species can adapt.
Define the term nucleic acid
Large polymers formed from nucleotides. Contain C, N, P, N, O
Give two examples of antibiotic resistant bacteria.
MRSA, C.difficile
State the functions of blood as a whole.
Main function is transport of : 1. Oxygen and Co2 2. Digested food from small intestine 3. nitrogenous waste products from cells to excretory organs 4 .chemical messages (hormones) 5. Food molecules 6. Platelets 7. Cells and antibodies involved in immune response
Define the term pathogen
Microorganisms that cause disease
Explain why enzymes are necessary to life.
Most processes necessary to life involve chemical reactions which need to happen very fast -so are catalysed by an enzyme.
Define effector
Muscle or gland which carries out bodies response to a stimulus
Define the term effector
Muscle or gland which carries out body's response to a stimulus
Define the term myogenic
Muscle which has it's own intrinsic rhythm
Outline why the majority of mutations do not have an influence on phenotype
Mutation is random majority of DNA is non-coding mutations more likely to occur in non-coding regions mutations in non-coding regions do not affect phenotype
Define deletion
Mutations where one or more nucleotides are deleted and lost from the DNA strand
approx how many nephrons in each kidney?
1 million
Define the term protein
1 or more polypeptide chains arranged as a complex macromolecule
Name 3 methods of ex situ conservation.
1. Botanic gardens 2. Seed banks 3. Captive breeding programmes
Describe 3 main issues for biodiversity that have come about due to an increased human population size.
1. Deforestation 2. Agriculture (increasing amount of land has to be farmed and this has resulted in large amounts of land being cleared and in many cases planed with a single crop monoculture) 3. Climate change
Describe 3 mechanisms that can regulate protein synthesis at the translational level.
1. Degradation of mRNA - the more resistant the molecule the longer it will last in the cytoplasm - greater quantity of protein synthesised 2. Binding of inhibitory proteins to mRNA - prevents it binding to ribosomes and the synthesis of proteins 3. Activation of initiation factors which aid the binding of mRNA to ribosomes
Define sympathetic nervous system
1. Division of the autonomic nervous system 2. Initiates flight or fight responses 3. Neurotransmitter - noradrenaline
Describe how a spirometer can be used to measure tidal volume
1. Don't breathe through nose 2. Subject breathes evenly 3. Measure amplitude of the waves 4. Measure at least 3 and take the mean 5. As you breathe in the lid and pen move down
Draw two water molecules and label the bond that links them together
1. Draw two water molecules 2. Dotted line between the oxygen of one and a hydrogen of another and label it hydrogen bond
Elastin
1. Fibrous protein 2. Found in elastic connective tissue such as skin, large blood vessels and some ligaments. 3. It's elastic so allows tissues to return to their original shape after they have been stretched
List the full names of the 5 possible nitrogenous bases in nucleic acids.
1. Guanine- Purine 2. Adenine- Purine 3. Thymine- Pyrimidine 4. Cytosine- Pyrimidine 5. Uracil- Pyrimidine
Name the type of cell which makes up the liver and describe the adaptations they have for their functions
1. Hepatocytes have a large nuclei 2. prominent Golgi apparatus 3. lots of mitochondria, indicating they are very metabolically active cells
Name the two hormones involved in regulating blood glucose concentration
1. Insulin 2. Glucagon
State the roles of ATP in muscle contraction.
1. Muscle contraction requires large quantities of energy 2. This is provided by the hydrolysis of ATP into ADP and phosphate 3. The energy is required for the movement of the myosin heads and to enable the sarcoplasmic reticulum to actively reabsorb calcium ions from the sarcoplasm.
State the molecules required for oxidative phosphorylation
1. Oxygen 2. Reduced NAD and FAD
Name, and give an example of, 4 different types of tropism.
1. Phototropism- response to light 2. Geotropism- response to gravity 3. Chemotropism- response to chemicals 4. Thigmotropism- response to touch
Explain how the (relative) age of fossils can be determined
1. Sediment is deposited on the earth to form layers of rock 2. Different layers correspond to different geological eras 3. Within the different rock layers the fossils found are quite different - forms sequence from oldest to youngest- shows how organisms have gradually changed
Name the 4 main types of T lymphocytes
1. T helper cells 2. T killer cells 3. T memory cells 4. T regulator cells
Explain why antibiotics do not work on viral infections.
1. Target things only bacteria have 2. Viruses use our system to reproduce to stop they would kill our cell as well
Label and annotate an action spectrum graph to explain what it shows.
1. Wavelength on bottom 2. Relative effectiveness in photosynthesis 3. Same sort of pattern as relative absorption graph 4. Dip at green wavelength
Label and annotate an absorption spectrum graph to explain what it shows.
1. Wavelength on bottom and absorbance on y-axis 2. Peaks at dark blue and red 3. Troughs at green and light blue 4. This shows that plants are most suited to absorbing red/ dark blue light and reflect green light 5. look at it in book
Explain with the use of diagrams why glycosidic bonds are called 1,4 or 1,6.
1. because the bond either happens with the hydroxyl group from the 1st carbon in the structure and the 4th carbon. 2. or with the 1st carbon and the 6th carbon
stages of slide production
1. fixing 2. sectioning 3. staining 4. mounting
Describe how muscle is specialised for its function
1. shortens in length in order to move bones which move different pars of the body. 2. Skeletal muscle fibres- attach to bone and contain myofibrils which contain contractile proteins. 3. There are different types of muscle fibres
Draw a dipeptide and label the peptide bond.
2 amino acids connected with a bond between the carbon atom and the nitrogen atom. Draw it
Define polymorphic
A gene with two or more possible alleles
Define the term vector
A living or non-living factor that transmits a pathogen from one organism to another e.g. malaria mosquito
Draw, and label, the basic structure of a nucleotide.
A phosphate group attached to a nitrogenous base attached to a pentose sugar. They all contain the elements H, P, O, N
Define pluripotent
A stem cell that can differentiate into any type of cell, but not form a whole organism
Define advantageous allele
A variety of a gene that provides a selective advantage to the organism
what is an artefact?
A visible structural detail caused by processing the specimen and not a feature of the specimen.
Describe the role of Kupffer cells in the liver
Act as resident macrophages of the liver, ingesting foreign particles and helping to protect them from disease
metabolism is...
All of the chemical reactions that occur within an organism
Define acetylcholine
An example of an excitatory neurotransmitter
Endoplasmic Reticulum (ER)
An extensive membranous network in eukaryotic cells enclosing flatterned sacs called cristernae. it is connected to the outer membrane of the nucleus
Define the term exoskeleton
An external skeleton of some organisms- made of chitin and is waterproofed to reduce water loss.
State how the hydrostatic pressure is generated in the heart
By the contracting of the ventricles
Define the term centrioles
Component of the cytoskeleton of most eukaryotic cells composed of microtubules. They are involved in the development of spindle fibres in cell division.
State the types of graph used to represent continuous and discontinuous variation within a population
Continuous- frequency tables which are then plotted onto a histogram, a curve is then normally drawn to show a trend. Discontinuous- bar chart, pie chart
Define the term core body temperature
Core body temperature refers to the temperature of the internal environment of the body
Name 4 expulsive reflexes and explain their value for protection against pathogens.
Coughs and sneezes- eject pathogen-laden mucus from the gas exchange system Vomiting and diarrhoea- expel the contents of the gut along with any infective pathogens.
Define the term phosphodiester bond
Covalent bonds formed between the phosphate group of one nucleotide and the hydroxyl group of another.
Explain the biological significance of water being cohesive
Creates water column of transpiration stream and creates a surface on which small organisms are supported
Define the critical value
Critical value- A critical value is the point (or points) on the scale of the test statistic beyond which we reject the null hypothesis
Describe how to carry out an investigation to investigate how the rate of diffusion is affected by surface area.
Cut different sizes of agar jelly with phenolphthalein indicator in. Put into a beaker of NaOH and time how long it takes for the agar to turn pink.
Prokaryotic cell main features
DNA ribosomes cell wall of peptidoglycan flagella
Draw and label a diagram of the structure of DNA.
DNA is composed of two polynucleotide strands joined together by hydrogen bonding in a double-helix shape. The two polynucleotide strands are anti parallel- this means they run in opposite directions.
Define the term taxonomy
Define the term taxonomy
Carbohydrates- name of dimer
Disaccharide e.g sucrose, lactose, maltose
Define epigenetics
External control of genetic regulation
Lipids- Building blocks
Fatty acids and glycerol
Lipids- Is the macromolecule a polymer
No
Define the term "chromatid"
One arm of a double stranded chromosome
Define advantageous characteristic
One form of a part of an organism's phenotype that provides it with a selective advantage
Define the term respiratory substrate
Organic molecules broken down in respiration
Define resting potential
Potential difference across the membrane of the axon of a neurone at rest
Define photosystem
Protein complexes involved in the absorption of light and electron transfers in photosynthesis.
Outline the structure of the two types of nitrogenous base.
Purines- larger bases which contain a double carbon ring structure Pyrimidines- smaller bases which contain a single carbon ring structure
Define the term sino-atrial node (SAN)
Region of the heart that initiates a wave of excitation that triggers the contraction of the heart
Define RuBisCO and state its long name
Ribulose bisphosphate carboxylase The key enzyme involved in the first step of carbon fixation in photosynthesis
Interpret a graph of ventricular volume
Rises as the atria contract and the ventricles fill with blood/Drops suddenly as blood is forced out into aorta hen semi-lunar valves open/Volume increases as ventricles fill with blood again
Define the term complementary base pairing
Specific hydrogen bonding between nucleic acid bases. A-T/U and C-G
Outline the structure and functions of the nucleus
Structure 1. has a double membrane (nuclear envelope) 2. it has pores- nuclear pores 3. the nucleus contains chromatin which is made form DNA and proteins 4. it often contains a nucleolus Function 1. Controls cell activities 2. contains instructions to make proteins 3. the pores allow substances (RNA) to move between the nucleus and the cytoplasm
Give an example of a non-reducing sugar
Sucrose
Define the term specific
The active site is only complementary to one type of substrate.
Define the term gill arch
The bony structure that supports the gill filaments,
Define sarcolemma
The cell membrane of a muscle fibre cell
Define the terms "facilitated diffusion"
The diffusion of particles through carrier proteins or channel proteins in the plasma membrane
Define the term zygote
The initial diploid cell formed when two gametes are joined by means of sexual reproduction. Earliest stage of embryonic development.
Define the term endodermis
The layer of cells surrounding the vascular tissue of the roots,
Define nerve impulses
The movement of an action potential along a nerve fibre in response to a stimulus
Define active immunity
The type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen.
Define heterochromatin
Tightly packed DNA causing chromosomes to be visible during cell division
Define passive immunity
Type of immunity when you are given antibodies made by a different organism
Define the term pandemic
When a communicable disease spreads rapidly to a lot of people across a number of countries
Define carbon fixation
When carbon is incorporated into an organic molecule
Describe the function of noradrenaline
Works with adrenaline in response to stress, producing effects such as increased heart rate, widening of pupils, widening of air passages and the narrowing of blood vessels in non-essential organs
Define the term resolution with reference to microscopy
ability to see individual objects as separate
Water molecules are more strongly cohesive to each other than they are to
air resulting in water having a "skin" of surface tension (pond skaters inhabit the surface of water. surface tension is enough to support small insects such as pond skaters)
where is the blood filtered?
at the start of the nephrons
location and function of KUPFFER CELLS
attached to the walls of the sinusoids and remove bacteria and break down old red blood cells
excess insulin can cause problems with
blood sugar levels
In basic light microscopy the sample is illuminated from below with white light and observed from above =
brightfield micropsopy
How is the bile duct connected to the central vein?
by tubes called CANALICULI
Why does an eyepiece graticle not have units?
eyepiece graticule is arbitrary scale / calibrated for each lens using stage micrometer
artefacts appear in both...
light and electron microscopy
the first types of microscope to be developed were:
light microscopes in the 16th-17th century
Draw and label a diagram of a mitochondrion.
look at book and draw it
Define mature mRNA
mRNA after the removal of introns and any other post-transcriptional changes
VACUOLES
membrane lined sacs nin the cytoplasm containing cell sap. many plant cells have large permanent vacuoles which are very important in maintainance of turgor so that the contents of the cell push against the cell wall and maintain a rigid framework for the cell
State the symbols used for millimetres, micrometres and nanometres.
milimetres- mm micrometres- um nanometres- nm
Idea of mesosomes observed by microscopes nowadays?
now widely thought that the majority of mesosomes observed are actually artefacts produced by the chemicals used in the fixation process in electron microscopy preparation which damage bacterial cell membranes
The kidneys are...
organs of excretion
The liver removes...
other harmful substances from the blood
if the outcome decreases activity it involves the...
parasympathetic nervous system
Proteins- Bonds that link the building blocks together
peptide covalent bond
compare reproduction in prokaryotes and eukaryotes
prokaryotic = binary fission eukaryotic = asesxual or sexual
Compare DNA in prokaryotes and eukaryotes
prokaryotic = circular eukaryotic = linear
urine dosent usually contain...
proteins and blood cells as too big to be filtered out of the blood glucose, amino acids and vitamins as theyre actively reabsorbed back into blood
Define the term "prokaryotic cell".
single-celled organism without a nucleus or membrane-bound organelles
Why must specimens be thin when preparing slides?
so light can shine through it and details can be seen
Nitrogenous waste can't usually be:
stored by the body (this means excess amino acids can be damaging as they store nitrogen in their amino groups)
Define the term "highly conserved" & in relation to homeobox genes/sequences
(VERY SIMILAR) sequences have changed very little during evolution of different organisms that possess these homeobox sequences they are very important mutation would alter body plan many genes would be affected mutation likely to be selected agains = LETHAL
Label (and annotate with adaptations for gas exchange) photomicrographs of alveolar tissue, tracheae and tracheoles of insects, and gill filaments and lamellae of bony fish.
---
Draw a diagram of a phospholipid, label its components and annotate with their properties.
-Two hydrophobic fatty acid tails - one hydrophillic (polar) phosphate head
examples of specimens which can be sectioned then prepared using a dry mount:
-muscle tissue -plants
.
.
Name and describe the two causes of variation
1. An organism's genetic material- differences in the genetic material an organism inherits from its parents leads to genetic variation 2. The environment in which the organism lives- this causes environmental variation
Name the 4 types of meristem in plants and describe where they are and their effect on the growth of the plant.
1. Apical meristems at the tips of roots and shoots 2. Lateral bud meristems giving rise to side shoots 3. Lateral meristems (in cambium) are responsible for roots and shoots getting wider 4. Intercalary meristems, located between the nodes where the leaves and buds branch off the stem, cause shoots to get longer
Name the 2 pathways by which water travels across the root to the xylem.
1. Appolast pathway 2. Symplast pathway
Describe how the body hair or feathers can be raised
1. As body temp falls, the erector pili muscles in the skin contract, pulling the hair or feathers of the animal erect 2. This traps an insulating layer of air and so reduces cooling through the skin 3. effective way to reduce heat loss to the environment 4. Humans- has little effect
Describe how total cross sectional area of blood vessels varies across the circulatory system.
1. As the total cross-sectional area of the vessels increases, the velocity of flow decreases. 2. Blood flow is slowest in the capillaries, which allows time for exchange of gases and nutrient
Describe the 2 ways of classifying bacteria and state the different types of bacteria in each way.
1. Basic shape- rod shape (bacilli), spherical (cocci) 2. Cell wall- Gram staining- gram positive bacteria are purple/blue under microscope (MRSA), gram negative appear red (E.coli)
Explain why temperature needs to be maintained within a narrow range with cells.
1. Because enzymes controlling chemical reactions needed for life are very temperature sensitive 2. If temperature gets to high they will dentature
State the two receptors that detect changes in the blood
1. Chemoreceptors (chemical receptors) 2. Baroreceptors (pressure receptors)
state the difference between depolarisation, repolarisation and hyperpolarisation
1. Depolarisation - voltage/potential difference becomes more positive 2. repolarisation - voltage/potential difference becomes more negative 3. hyperpolarisation - when potential difference is lower than resting potential
Describe how stem cells could be used to treat diabetes
1. Diabetes researchers have been searching for ways to replace the faulty β cells in the pancreatic islets of diabetic sufferers 2. As type 1 diabetes results from the loss of a single cell type and there is evidence that a relatively small number of islet cells can restore the insulin production 3. It is likely that the stem cells used in diabetes would be taken from embryos 4. Totipotent stem cells have the potential stem cells have the potential to grow into any body's cell types
Draw a table to compare treating kidney failure with dialysis and treating kidney failure with transplantation
1. Dialysis is more readily available than donor organs 2. Dialysis enables the patient to lead a relatively normal life 3. However dialysis patients have to monitor their diet carefully and need regular sessions on the machine 4. Long-term dialysis is much more expensive than a transplant and can eventually cause damage to the body 5. Kidney transplant patients are free from the restrictions which come with regular dialysis sessions and dietary monitoring
Define parasympathetic nervous sytem
1. Division of the autonomic nervous system 2. Relaxing responses 3. Neurotransmitter- acetylcholine
State the 3 domains of life and the 6 kingdoms in the 'Three Domain system'- Woese's system
1. Domains- Bacteria, Archaea and eukarya 2. Kingdoms- Eubacteria, archae-bacteria, protoctista, plantae, fungi, animalia
Define tubule/central duct/pancreatic duct
1. Exit way for enzymes produced by the acini into the small intestine 2. A tube leading from the pancreas to the duodenum
Keratin
1. Fibrous protein 2. Found in many of the external structures of animals such as skin, hair, nails, feathers and horns 3. Can be flexible or hard and tough
Describe how an organism generates heat internally.
1. From metabolic processes 2. Metabolic rate of endotherms is much higher than ectotherms
Describe the environmental conditions where water loss, or water access, may become a real problem for plant species.
1. Hot, dry, breezy conditions- water will evaporated very rapidly 2. Cold or icy climate- water is frozen
Define the term "synthetic biology" and give 2 examples of how synthetic biology may lead to better medical treatments.
1. Involves using technology to design and make things like artificial proteins, cells and even microorganisms. 2. scientists are looking at engineering bacteria to destroy cancer cells while leaving healthy body cells intact 3. Drugs produced by organisms that wouldn't normally make that chemical- genetic engineering
Explain how to calculate the actual size of an image using the magnification formula.
1. Measure it in mm 2. convert to um by multiplying by 1000 3. then divide it by magnification to get actual size of image.
Describe the mechanism of expiration in bony fish.
1. Mouth closes, the operculum opens and the side of the opercular cavity move inwards. 2. These actions increase the pressure in the opercular cavity and force water over the gills and out of the operculum. 3. The floor of the buccal cavity is steadily moved up, maintaining a flow of water over the gills.
Explain why not completing a course of antibiotics may lead to antibiotic resistance developing.
1. Only weaker bacteria will be killed if you don't finish it which allows stronger bacteria to become resistant
Draw a table to compare chemiosmosis in photosynthesis with chemiosmosis in respiration.
1. Oxidative phosphorylation in respiration 2. Photophosphorylation in photosynthesis 3. In photosynthesis ATP is used to synthesise glucose and other organic molecules 4. In respiration ATP produced provides the energy needed by metabolic processes and reactions essential to life.
Describe the structure of callose.
1. Polysaccharide polymer of beta glucose 2. linked by 1,3 and 1,6 glycosidic bonds 3. It is different to cellulose so pathogen requires a different enzyme to break it down
Describe how to carry out an experiment to investigate how the rate of diffusion is affected by temperature.
1. Prepare agar jelly and cut into equal sized cubes. then prepare several different boiling tubes containing the same concentration of HCl and put them in separate water baths of different temperatures. 2. When the HCl has reached desired temp put agar jelly in and time how long it takes the cube to go colourless.
Define β-cell
1. Present in the islet of Langerhan 2. They produce and secrete insulin 3. stained blue
Describe the role of plasma cells
1. Produce antibodies to a particular antigen and release them into the circulation
State the stages of meiosis in order.
1. Prophase 1 2. Metaphase 1 3. Anaphase 1 4. Telophase 1 5. Prophase 2 6. Metaphase2 7. Anaphase 2 8 Telophase 2
Name the proteins produced from the structural genes in the lac operon
1. Protein 1- lac Z- Beta galactosidase- breaks down lactose 2. Protein 2- lac Y- Lactose permease- brings lactose into cell 3. Protein 3- lac A- Transacetylase- unknown function
Describe how sweating is decreased
1. Rates of sweating will decrease and sweat production will stop entirely 2. This greatly reduces cooling by the evaporation of water from the surface of the skin
*Explain how prozac helps treat depression by blocking reuptake of serotonin into the presynaptic neurone
1. Serotonin would normally be taken back into the presynaptic neurone to be used again 2. prozac would prevent this occurring resulting in higher levels of serotonin in synapse 3. more serotonin can bind to neurotransmitter receptors on postsynaptic membrane 4. depolarisation threshold reached and more action potentials so nervous system more stimulated reducing depression symptoms
Describe and explain how to investigate any of the factors that affect the rate of enzyme-controlled reactions.
1. Set up boiling tubes containing the same volume and concentration of H202. 2. To keep pH constant add equal volumes of suitable buffer solution to each boiling tube. 3. Have a trough of water with an upside down measuring cylinder in it. A delivery tube leading to a boiling tube with a bung. 4. Put each tube in water baths at different temperatures along with another tube of catalase. leave for 5 mins 5. use a pipette to add the same of catalase to each boiling tube. then add the bung . 6. Record how much oxygen is produced in the first min. 7. calculate the mean rate of reaction at each temperature by dividing oxygen produced by time taken. Change different factors accordingly.
Describe how human activity has resulted in evolution in populations of the bacterium Staphylococcus aureus, the Sheep blowfly Lucilia cuprina, and the bacterium Flavobacterium.
1. Sheep blowflies- laid eggs in sheep's tails, pesticide was introduced and they became resistant to it 2. Bacterium- a strain of bacteria which have evolved to digest nylon and live in waste water form factoids that produce nylon 3. Staphylococcus aureus- has developed resistance to many antibiotics. when exposed resistant individuals survived etc.
What happens when a normal plant shoots is exposed to unilateral light
1. Shoot bends towards the light 2. The shoot is positively phototropic, bending occurs behind the tip
Explain why blood smears need to be stained for viewing under the light microscope and name a stain used for this procedure.
1. Shows the different nuclei of lymphocytes making them easier to identify 2. Identifying the different numbers of different types of lymphocytes indicates if a non-specific or specific immune response is taking place.
Outline the process of apoptosis
1. Similar to sculptor and wood 2. The shape is revealed as material is removed bit by bit- removes unwanted cells and tissues to shape different body parts 3. Cells undergoing apoptosis can also release chemical signals which stimulate mitosis and cell proliferation leading to the remodelling of tissues 4. Regulated by Hox genes
State 5 properties of ATP and explain why each makes it ideally suited to function as an energy transfer molecule.
1. Small- moves easily into, out of and within cells 2. Water soluble- energy-requiring processes happen in aquoeus environments. 3. Contains bonds between phosphates- with intermediate energy large enough to be useful for cellular reactions but not so large that energy is wasted 4. Releases energy is small quantities- quantities are suitable to most cellular needs, so energy is wasted as heat. 5. Easily regenerated- can be recharged with energy
Explain why water move from the soil into root hair cells.
1. Soil water has a very low concentration of dissolved minerals so has a very high water potential 2. The cytoplasm and vacuolar sap of the rot hair cell contain many different solvents including sugars, mineral ions and amino acids so the water potential in the cell is lower 3. So water moves into the root hair cells by osmosis
State 4 differences between the autonomic nervous system and the somatic nervous system
1. Somatic is voluntary and autonomic is involuntary 2. Somatic most neurones are myelinated, autonomic most are unmyelinated or lightly myelinated 3. Somatic carry impulses to skeletal but autonomic cary it to cardiac, smooth muscle and glands 4. Somatic- 1 neurones to connect CNS to effector but autonomic- at least 2 neurones to connect CNS to effector
Draw, label and annotate diagrams of transverse sections (cross-sections) through a typical stem, root and leaf of an herbaceous dicotyledonous plant.
1. Stem- outer layer is epidermis, middle layer is the cortex, middle area is the parenchyma and little beans half in parenchyma and half in cortex are vascular bundles- half closest to middle is xylem, half pointing out is phloem 2. Root- Root hairs pointing out, exodermis is outer layer, then epidermis, then cortex, then a endodermis surrounds the middle circle- where the xylem makes and x shape and the phloem are 4 circles in between the branches of the x 3. Leaf- upside down hill shape- circle in the hill- lower half of circle is the phloem and upper is the xylem,
State the two types of hormone and identify which type adrenaline is.
1. Steroid hormones- lipid soluble. e.g. oestrogen - Pass through lipid component of cell membrane and bind to steroid hormone receptors to form a hormone-receptor complex. -Receptors may be present in cytoplasm or nucleus depending on hormone. -Hormone-receptor complex formed acts as a transcription factor which facilitates or inhibits the transcription of a specific gene 2. Non steroid hormones- adrenaline -hydrophillic so cannot pass directly through cell membrane - bind to specific receptors on the cell surface membrane of the target cell. - Triggers a cascade reaction mediated by chemicals called second messengers
Draw, label and annotate a diagram to show the arrangement of neurones in the "withdrawal of the hand from a heat stimulus" reflex arc and the actions that occur in the stimulus-response pathway
1. Stimulus heat from candle flame 2. Thermoreceptor in skin detects heat 3. Sensory neurone passes nerve impulses to spinal cord 4. Relay neurone passes impulses across the spinal cord 5. Motor neurone passes impulses to the muscle 6. Effectory contracts 7. Response hand is moved quickly away from flame
What does the chemoreceptors
1. Stimulus- chemicals 2. Example receptor- Olfactory receptor (detects smell) 3. Example of organ- nose
What does thermoreceptor
1. Stimulus- heat 2. Example receptor- end-bulbs of Krause 3. Example of organ- Tongue
Label a diagram of a spirometer and annotate with the function of each component.
1. Subject breathes in and out until Oxygen is used up- breathes into a mouth piece which has a tube connected to the oxygen chamber and has nose clips attached 2. The tube has soda lime in it to absorb the CO2 3. As the person breathes in and out the lid of the chamber moves up and down- movements are recorded by pen attached to lid of chamber, this writes on rotating drum creating a spirometer trace. 4. Find online labelling acivity
Describe how the water and assimilates in phloem move from source to sink.
1. Sucrose in the companion cell diffuses into the sieve tube element through plasodesmata down the concentration gradient 2. The water potential is lowered, so water follows passively by osmosis and increases the hydrostatic pressure at the source. 3. Water and dissolved sucrose moves down the phloem form higher to lower hydrostatic region (at the sink)- Mass flow 4. At the sink- sucrose is removed from the sieve tube into surrounding cells by diffusion or active transport. 5. This increases the water potential of the sieve tube so water moves out of the sieve tube by osmosis to lower the pressure.
Describe the methods for increasing the rate of photosynthesis in a greenhouse
1. Sunlight- artificial lighting may be used in winter, blinds can be rolled up or down to control the amount of light entering 2. Humidity- if too high it encourages the growth of fungi and other organisms, but plants like humidity- to raise it using a misty spray of water and lowered by opening ventilators or increasing temperature 3. CO2- extra CO2 can be provided by burning gas (paraffin) or it can be released form cylinders 4. Temperature- can be controlled by opening and closing ventilators and by adjusting the heaters 5. Water in soil- must get exact amount- so plant doesn't wilt or become waterlogged.
State 3 chemical defences plants have against herbivory
1. Tannins 2. Alkaloids 3. Terpenoids
Describe what happens in anaphase
1. The centromeres divide, separating each pair of sister chromatids. 2. The spindles contract, pulling chromatids to opposite ends of the cell, centromere first
Describe what happens during the Telophase 2 stage of meiosis
1. The chromatids assemble at the poles as in mitosis. 2. The chromosomes uncoil and form chromatin again 3. The nuclear envelope reforms and the nucleolus becomes visible. 4. Cytokenisis results in the division of the cells forming 4 daughter cells- haploid and genetically different.
Describe what happens in telophase
1. The chromatids reach the opposite poles on the spindle. 2. They uncoil and become long and thin again- chromosomes again 3. A nuclear envelope forms around each group of chromosomes, so there are now two nuclei
Name the 3 main areas of the kidney and describe the role of each area
1. The cortex- dark outer layer. Where the blood is filtered and it has a very dense capillary network carrying the blood from the renal artery to the nephrons 2. The medulla- lighter in colour. It contains the tubules of the nephrons that form the pyramids of the kidney and the collecting duct 3. The pelvis- is the central chamber where the urine collects before the passing out down the ureter
Describe what happens during cytokenisis
1. The cytoplasm divides- in animal cells, a cleavage furrow forms and the cell-surface membrane is pulled inwards by the cytoskeleton until it is close enough to fuse around the middle. 2. There are now two daughter cells that are genetically identical to the original cell and to each other. 3. Cytokenisis begins in anaphase and ends in telophase. But is separate to the process of mitosis.
Describe the process of inspiration linking the action of muscles, to the movement of structures, the change in pressure within the lungs and the direction of airflow.
1. The external intercostal and diaphragm muscles contract 2. This causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax (space where the lungs are) 3. As the volume increases the lung pressure decreases (below atmospheric pressure) 4. This causes air to flow into the lungs 5. Inspiration is an active process
Describe the process of oxidative phosphorylation.
1. The hydrogen atoms that have been collected by coenzymes NAD and FAD are delivered to electron transport chains present in the membranes of the cristae of the mitochondria 2. The hydrogen atoms dissociate into hydrogen ions and electrons 3. The high energy electrons are used in the synthesis of ATP by chemiosmosis 4. Energy is released during redox reactions as the electrons reduce and oxidise electron carriers as they flow along the electron transport chain 5. The energy is used to create a proton gradient leading to the diffusion of protons through ATP synthase resulting in the synthesis of ATP 6. At the end of the chain the electrons combine with hydrogen ions and oxygen to form water 7. Oxygen is the final electron acceptor and the electron chain cannot operate unless oxygen is present.
Draw a diagram showing how the hypothalamus uses both the nervous system and the endocrine system to coordinate the physiological responses associated with the "fight or flight" response
1. The hypothalamus activates both the sympathetic nervous system and the adrenal-cortical system by releasing CRF (corticosteroid releasing factor) into the pituitary gland 2. The sympathetic nervous system impulses activate glands and smooth muscles 3. The sympathetic nervous system activates the adrenal medulla so it produces noradrenaline and adrenaline into the bloodstream 4. The pituitary gland (stimulated by CRF) secretes the hormone ACTH (adrenocorticotropic hormones) which stimulates the adrenal cortex to release a number of different corticosteroid hormones into the bloodstream 5. Combination of above responses result in the physiological responses in the flight or fight response
Describe what happens during the Metaphase 2 stage of meiosis
1. The individual chromosomes assemble on the metaphase plate as in mitosis. 2. Due to crossing over the chromatids are no longer identical so there is independent assortment again and more genetic variation produced.
Describe and explain how an action potential is transmitted along an unmyelinated axon
1. The initial stimulus causes a change in the sensory receptor which triggers an action potential in the sensory receptor, so the first region of the axon membrane is depolarised 2. This acts as a stimulus for the depolarisation of the next region of the membrane 3. The process continues along the length of the axon forming a wave of depolarisation 4. Once sodium ions are inside the axon, they are attracted by the negative charge ahead and the concentration gradient to diffuse further along inside the axon, triggering the depolarisation of the next section
Describe and explain the possible effects of insertion or deletion mutations
1. The insertion or deletion of a nucleotide or nucleotides leads to a frameshift mutation 2. It changes every successive codon from the point of mutation
Explain how increasing the enzyme concentration affects the initial rate of an enzyme-controlled reaction.
1. The more enzyme molecules there are the more likely a substrate molecule is to collide with one and form an enzyme-substrate complex. 2. Increasing the concentration of enzyme increases the rate of reaction. 3. But if the substrate amount it limited there comes a point when there's more than enough enzyme molecules to deal with all the available substrate. 4. So adding more enzyme has no further effect.
Describe and explain the advantage of myelination
1. The myelin sheath acts as an electrical insulating layer and allows these myelinated neurones to conduct the electrical impulse at a much faster speed than un-myelinated neurones 2. The nodes of Ranvier create gaps in the myelin sheath 3. The myelin sheath is an electrical insulator 4. In myelinated neurones the electrical impulse jumps from one node to the next as it travels along the neurone 5. This allows the impulse to be transmitted much faster 6. In non-myelinated neurones the impulse does not jump- transmits continuously along the nerve fibre so is much slower (conduct impulses 1 metre per second rather than 100 metres per second)
Draw and label a diagram showing the structure of a Pacinian corpuscle.
1. The sensory neurone is found within the centre of the centre of the corpuscle surrounded by layers of connective tissue 2. Each layer is separated by a layer of gel 3. Within the membrane of the neurone there are sodium ion channels- responsible for transporting sodium ions across the membrane 4. The neurone ending in the Pacinian corpuscle has a special type of sodium channel called a stretch mediated sodium channel 5. When these channels change shape their permeability to sodium also changes
Explain why the "all-or-nothing" response of neurones means that information must be transmitted by the frequency of impulse transmission.
1. The size of the stimulus doesn't affect the size of the action potential 2. But it does effect the number of action potentials that are generated in a given time 3. The larger the stimulus the more frequently the action potentials are generated 4. It is the frequency of action potentials that affect the response initiated not the size
Explain the role of active transport by endodermal cells for the movement of water
1. The solute concentration in the cytoplasm of the endodermal cells is relatively dilute compared to the cells in the xylem 2. The endodermal cells appear to move mineral ions into the xylem by active transport 3. As a result the water potential of the xylem cells is much lower than the water potential of the endodermal cells 4. This increases the rate of water moving into the xylem by osmosis
Describe what happens during the Anaphase 1 stage of meiosis
1. The spindles contract, pulling the pairs apart- one chromosome goes to each pole. the chromatids stay attached to each other. 2. Sections of DNA on chromatids which became entangled during crossing over now break off and rejoin- some resulting in the exchange of DNA. Forms recombinant DNA.
Define the term "antagonistic system" in relation to the sympathetic and parasympathetic nervous systems, and outline how they co-ordinate responses.
1. The sympathetic and parasympathetic have antagonistic effects on the organs 2. The action of ones system opposes the action of the other 3. Under normal conditions impulses are passing along the neurones of both systems at a relatively low rate 4. Changes to conditions lead to an altered balance between the two systems which leads to an appropriate response
Describe the adaptations that make the bony fish gas exchange system an efficient exchange surface.
1. The tips of adjacent gill filaments overlap- increases resistance to the flow of water over the gill surfaces and slows the movement of water- more time for gaseous exchange. 2. Countercurrent exchange system
Describe the structure of the bronchus
1. The trachea divides to form two bronchi each leading to a lung. 2. Similar in structure to trachea with same supporting rings of cartilage.
Describe how chromatin remodelling allows the expression of some genes but not others
1. The transcription of genes is not possible when DNA is tightly wound because RNA polymerase cannot access the genes 2. The genes in euchromatin can be freely transcribed 3. Proteins synthesis does not occur during cell division as it is heterochromatin but it does during interphase between cell divisions as it is euchromatin 4. This is a simple form of regulation that ensures the proteins necessary for cell division are synthesised in time 5. It also prevents the complex and energy - consuming process of protein synthesis form occurring when cells are actually dividing.
Describe the process of repolarisation
1. The voltage-gated sodium ion channels are closed and potassium ion channels are open 2. Potassium ions diffuse out of the axon down their electrochemical gradient. This reduces the charge, resulting in the inside of the axon becoming more negative than the outside 3. Initially lots of potassium ions diffuse out of the axon, resulting in the inside of the axon becoming more negative than its normal resting state- hyperpolarisation 4. The voltage-gated potassium channels now close 5. The sodium-potassium pump causes sodium ions to move out of the cell, and potassium ions move in 6. The axon returns to resting potential- repolarised
Describe the role of the Bowman's capsule
1. The wall of the Bowman's capsule also involves special cells called podocytes that act as an additional filter 2. They have extensions called pedicels that wrap around the capillaries forming slits that make sure any cells, platelets, or large plasma proteins that have managed to get through the epithelial cells and the basement membrane do not get through into the tubule itself 3. The volume of blood that is filtered through the kidneys in a given time is known as the glomerular filtration rate.
Describe the evidence for climate change and the role of human activities in climate change.
1. The warming trend over the last 50 years is nearly twice that for the previous 100 years 2. The average amount of water vapour in the atmosphere has increased over land and ocean- warmer air can hold extra water vapour. 3. The global average sea level rose more than in 19th century. 4. Average temperature of oceans has increased 5. Mountain cover and snow glaciers have declined on average 6. Upward trend in the amount of precipitation
Define countercurrent exchange system and explain why it is important
1. The water moving over the gills and the blood in the gill filaments flow in different directions. 2. A steep conc gradient is needed for fast efficient diffusion. 3. Because they flow in opposite directions, a countercurrent exchange system is set up. 4. This ensures a steeper concentration gradients are maintained than if they flowed in the same direction.- the water most depleted in oxygen is put next to blood with no oxygen- still conc gradient 5. This results in more gaseous exchange can take place. 6. Bony fish remove around 80% oxygen, cartilaginous fish have parallel systems and can only extract 50%.
Why are there many neuromuscular junctions along a length of a muscle and how does the response change for different required forces
1. There are many neuromuscular junctions along the length of a muscle to ensure that all the muscle fibres contract simultaneously 2. If there was only one the muscle fibres would not contract together and therefore the contraction would not be as powerful and it would also be much slower, as a wave on contraction would have to travel across the muscle to stimulate the individual fibres to contract 3. All the muscle fibres supplied by a single motor neurone are known as a motor unit- the fibres act as a single nit 4. If a strong force is need, a large number of motor units are stimulated, whereas only a small number are stimulated if a small force is required.
Draw a diagram to show the components of the negative feedback mechanism that allows thermoregulation in endotherms.
1. There is a heat loss and heat gain centre in the hypothalamus 2. Too Hot a) Heat loss centre- activated when the temperature of the blood flowing through the hypothalamus increases b) This sends impulses through the autonomic motor neurones to effectors in the skin and muscles, triggering responses that act to lower the core temperature c) Warm receptors in skin detect change in temperature d) Vasodilation, Sweating, hair lowered as hair erector muscles relax. decreased metabolic rate 3. Too cold a) The heat gain centre is activated when the temperature of the blood flowing through the hypothalamus decreases b) It sends impulses through the autonomic nervous system to effectors in the skin and the muscles, triggering response that act to raise the core temperature c) Cold receptors in the skin detect changes in temperature d) Vasoconstriction, shivering, hair raised by contraction of hair erector muscles, increased metabolic rate
Describe how urine is tested for anabolic steroids
1. They are excreted in the urine 2. testing the urine using gas chromatography and mass spectrometry 3. The urine sample is vapourised with a known solvent and passes along a tube 4. The lining of the tube absorbs the gases and is analysed to give a chromatogram that can be read to show the presence of the drugs
Draw and label diagrams of a sensory neurone
1. They have one dendron which caries the impulse to the cell body 2. They have one short axon that carries the impulse away from the cell body 3. Dendrites branch of from the dendron and axon 4. The cell body is in the middle of the axon 5. Have a myelinated sheath and Nodes of Ranvier
Explain why plant cells don't burst by osmosis by referring to solute potential and pressure potential.
1. They have strong cellulose walls, when water enters by osmosis the increased hydrostatic pressure pushes the membrane against the rigid cell wall- turgor. 2. As the pressure increases it resists the entry of further water and the cell is turgid.
Define cell body
1. This contains the nucleus surrounded by cytoplasm 2. Within the cytoplasm there are large amounts of endoplasmic reticulum and mitochondria which are involved in the production of neurotransmitters 3. Neurotransmitters are chemicals which are used to pass signals from one neurone to the next
Describe the structure and location of the pituitary gland
1. This is found at the base of the hypothalamus and controls most of the glands in the body 2. It is divided into two sections. - Anterior pituitary- produces 6 hormones including follicle-stimulating hormone (FSH), which is involved in reproduction and growth hormones - Posterior pituitary (back section)- stores and releases hormones produced by the hypothalamus, such as ADH involved in urine production
Describe the structure and location of the hypothalamus
1. This is the main controlling region for the autonomic nervous system 2. It has two centres- one of the parasympathetic and one for the sympathetic nervous system 3. It has a number of functions: - Controlling complex patterns of behaviour such as feeding, sleeping and aggression - Monitoring the composition of blood plasma, such as the concentration of water and blood glucose- therefore it has a very rich blood supply - Producing hormones- it is an endocrine gland, that is, it produces hormones
Define temporal summation
1. This occurs when a single presynaptic neurone releases neurotransmitter as a result of an action potential several times over a short period 2. This builds up in the synapse until the quantity is sufficient to trigger an action potential
Define somatic nervous system
1. This system is under conscious control- used when you voluntarily decide to do something 2. E.g. when you decide to move a muscle to move your arm 3. It carries impulses to the body's muscles
State the information needed to determine the species richness and species evenness of an area.
1. Total number of organisms in one species 2. Total number of all organisms 3. And the sum of these two values
State the function of the phloem
1. Transports food in the form of organic solutes around the plant from the leaves where they are made in photosynthesis 2. It provides cells with the sugars and amino acids it needed for cellular respiration and synthesis of all other useful molecules.
Describe how the phloem is specialised for its function
1. Transports organic nutrients- sucrose from leaves and stems to everywhere 2. Composed of columns of sieve tube cells separated by perforated walls called sieve plates- so sap can move easily through them 3. Also have companion cells linked to by plasmodesmata- perform all the cellular reactions of the sieve tube cells i.e have lots of mitochodira to provide ATP 4. Substances can move easily through the sieve tubes element because they have very little cytoplasm and thin cell walls
Describe the characteristics of Prokaryotae
1. Unicellular 2. No nucleus or other membrane bound organelles- a ring of naked DNA- small ribosomes 3. No visible feeding mechanism- nutrients are absorbed through cell wall or produced internally by photosynthesis
Describe the characteristics of Fungi
1. Unicellular, multicellular 2. A nucleus and other membrane-bound organelles and a cell wall mainly composed of chitin 3. No chloroplasts or chlorophyll 4. No mechanisms for locomotion 5. Most have a body or mycelium made of threads or hyphae 6. Nutrients are acquired by absorption- mainly decaying material- they are saprophytic feeders- some are parasitic 7. Most store their food as glycogen
Explain, in general, why analysis of urine can act as a good diagnostic test for different diseases
1. Urine contains the breakdown products of a whole range of chemicals, including hormones and any toxins taken into the body 2. If you are affected by one of a number of different diseases, new substances will show up in your urine 3. The presence of glucose in the urine is a well-known symptom of type 1 and type 2 diabetes 4. If you have muscle damage large amounts of creatinine will show up in your urine
Describe a step by step method to investigate the effect of one factor (temperature, substrate concentration, or different respiratory substrate) on the rate of respiration
1. Use a respirometer 2. The potassium hydroxide in the apparatus absorbs CO2 so if the temperature is kept the same, any changes in the volume of air in the respirometer will be due to oxygen uptake 3. You can set up different respirometers with different conditions 4. Measure the distance the coloured fluid moves in the graduated tube after being left for 20 mins.
Suggest how the population size of plants and animals can be estimated.
1. Using a variety of sampling techniques such as a quadrat to estimate the population of a plant species in an area.
Draw and label a diagram to show the internal structure of a kidney
1. Very outer layer is the capsule 2. Then Cortex 3. Then Medulla is the inner layer 4. In the medulla is nephrons 5. The inner section in the medulla is the pelvis which have blood vessels on top
Explain the importance of excretion in maintaining metabolism and homeostasis
1. Waste products are toxic if they are allowed to build up 2. Maintains the water balance and pH
State 3 examples of hydrophytic plants.
1. Water lilies and water cress which grow at the surface 2. Duckweeds- submerged or free-floating 3. Bulrushes and yellow irises- grow at edge of water
State 3 examples of barriers to pathogens in plants
1. Waxy cuticle 2. Bark 3. Cellulose cell wall
Explain how the lac operon works when lactose is present in the growth medium
1. When lactose is present, it binds to the repressor protein causing it to change shape so it can no longer bind to the operator 2. As a result RNA polymerase can bind to the promoter, the 3 structural genes are transcribed and the enzymes are synthesised.
How does the negative feedback loop respond when there is an excess of water
1. When large amounts of liquid are taken in, the blood becomes more dilute and its water potential becomes less negative 2. Again, the change is detected by the osmoreceptors of the hypothalamus 3. Nerve impulses to the posterior pituitary are reduced or stopped and so the release of ADH by the pituitary is inhibited 4. Very little re absorption of water can take place because the walls of the collecting remain impermeable to water 5. In this way the concentration of the blood is maintained- and large amounts of dilute urine are produced.
Describe how activity changes the volume of tracheal fluid in the tracheoles, and explain the value of this occurring.
1. When oxygen demands builds up- Lactic acid builds up in the tissues- results in water moving out of the tracheoles (tracheal fluid) by osmosis- exposes more SA for gaseous exchange.
Draw, label and annotate a diagram to explain the movement of liquid into or out of a capillary (include example calculations).
1. When the hydrostatic pressure is higher than the osmotic pressure there is a net flow of fluid out of the capillary 2. When the hydrostatic pressure is lower than the oncotic pressure there is a net flow of fluid into the capillary by osmosis
Explain how a population of bacteria may develop resistance to an antibiotic.
1. You start with a population with no resistance o bacteria 2. A chance mutation in one bacterium produced a gene for antibiotic resistance- creating a population with a few antibiotic resistance bacteria 3. Antibiotic A applies a selection pressure- there is a strong natural selection for bacteria with a gene for antibiotic-resistance 4. This creates a population with mainly antibiotic-resistance 5. Continued selection pressure means almost all bacteria on the population will be antibiotic resistant
Outline how an ectotherm regulates its internal temperature using behavioural responses
1. bask in the sun 2. extend areas of their body to increase the surface area exposed to the sun 3. Increase temperature through conduction by pressing their bodies against the warm ground 4. Exothermic reaction (contracting muscles and vibrating wings) 5. shelter from the sun by seeking shade (hiding in rocks or caves or digging burrows) 6. Press bodies against cool, shady earth or stones or move into available water or mud 7. Orientate bodies their bodies so that the minimum surface area is expose to the sun 8. Minimise movements to reduce metabolic heat generated
how does the kidney excrete waste products?
1. blood enters through renal artery and passes through capillaries in cortex 2. as blood passes through capillaries substances are filtered out of the blood into long tubules that surround capllaries (ULTRAFILTRATION) 3. useful substances reabsorbed back into blood from tubules in the medulla and cortex (SELECTIVE REABSORPTION) 4. remaining unwanted substances pass along tubules, along ureter to bladder where theyre expelled as urine by the urethra 5. the filtered blood passes out of the kidneys through the renal vein
Cell theory states that:
1. both plants and animal tissue is composed of cells 2. cells are the basic unit of life 3. cells only develop from existing cells
Suggest how adrenaline can have different effects on different tissue types
1. cAMP activates different molecules in different cells 2. Different types of interactions between the receptor protein adenylyl cyclase
Outline the importance of micrscopes in the study of living organisms
1. cell is unit of life 2. many organisms unicellular 3. (most) cells are too small to see without microscope 4. cell components / organelles, are even smaller 5. need to see organelles to determine function
List the functions of phospholipids (2 functions)
1. cell membranes- make up part of cell surface membranes, add flexibility and act as a barrier in the cell- they make a phospholipid bilayer with hydrophillic heads pointing out and hydrophobic middle so water-soluble substances can't easily pass through
Describe the structure of a cellulose fibre.
1. cellulose molecules make hydrogen bonds with each other forming microfibrils. 2. these microfibrils join together forming macrofibrils, which combine to produce fibres 3. these fibres are strong and insoluble and are used to make cell walls. 4. cellulose is an important part of our diet, it is very hard to break down into monomers and forms the fibre necessary for a healthy digestive system.
Describe 3 sources of evidence for the cohesion-tension theory.
1. changes in the diameter of trees- when transpiration is at it's height during the day the tension in the xylem vessels is at it's highest too- tree shrinks in diameter. Opposite happens during the night 2. When a xylem is broken- when you cut a flower stem - air is drawn in rather than water leaking out 3. If the above happened, the plant can no longer move water up the stem as the continuous stream of water molecules held together by cohesion forces has been broken
in myelinated neurones:
1. conduction faster 2. depolarisation can only occur where voltage gated Na+ channels are present 3. myelinated neurones have longer sections with no channels present (channels further apart) 4. ion movement can only take place at nodes 5. longer local circuits 6. saltatory condiction
State 3 examples of xerophytic plants
1. conifers and marram grass found on sand dunes and coastal areas 2. Many plants in very cold or icy conditions- water is frozen 3. Cacti- deserts etc
Explain how diffraciton limits resolution
1. diffraction happens when light passes through structures 2. light waves spread out 3. light waves overlap 4. individual objects do not appear separate which causes blurring
Describe a step by step method for conducting thin layer chromatography to separate and identify photosynthetic pigments.
1. draw pencil line on chromatography paper 2. Plant extract is ground with propanone until a smooth dark pulp is achieved. 3. Transfer pigment with a capillary tube to teh strip creating a small spot on the pencil line 4. Put the strip in a chromatography tube with the spot at the bottom- solvent shouldn't reach the spot. 5. Leave and remove the strip once the solvent is about 1 cm from the top. Mark the solvent line and each pigment line with pencil. 6. Then calculate rf values to identify the pigments.
advantages of light microscopy?
1. easily available 2. relatively cheap 3. can be used to observe living organisms as well as dead, prepared specimens
Explain how to calculate the length of time each stage in the cell cycle takes given a sample of cells undergoing mitotic cell division and the total duration of the cell cycle.
1. find number of cells in that stage 2. Divide it by the total number of cells and multiply by 100 to get a percentage. 3. Find the amount of time in one stage by multiplying percentage by the total time spent
Draw, label and annotate a graph of an action potential occurring over time to show the different stages of an action potential and what happens at each stage
1. look p350 2. flat line at around -70 3. Goes up to form a curve, the peak of the curve at +40 4. A slight bump on the ascending line to show the threshold level 5. Descending line goes slightly past -70 and then goes back up to resting potential
Describe the process of Translation
1. mRNA moves to ribosome 2. tRNA molecules bind to mRNA 3. Anticodons match/bind to codons (tRNA anticodons bind to RNA codons) 4. Specific amino acid attaches to tRNA 5. Peptide bonds form between the amino acids- catalysed by the rRNA in the ribosome
Explain how to use a stage micrometer and eye-piece graticule to calculate the size of a specimen.
1. measure the specimen with the eyepiece graticule 2. then multiply it by the magnification factor 3. this will get the size of the specimen in micrometres
Lipids- examples of functions
1. membrane formation and creation of hydrophobic barriers 2. hormone production 3. electrical insulation necessary for impulse transmission 4. waterproofing 5. Thermal insulation 6. cushioning to protect vital organs 7. buoyancy for aquatic animals
Name two common stains and the molecules they bind to.
1. methylene blue - DNA 2. Giemsa - used to differentiate between different types of blood cell 3. Eosin - cytoplasm turn pink
Describe and explain the characteristics of a good slide preparation.
1. no air bubble- artefact 2. staining if needed 3. glass and transparent 4. coverslip - protection 5. thin specimen- good quality and a good size 6. good liquid levels 7. clean
all structures in eukaryotic cell 14 things
1. nucleus 2. nucleolus 3. nuclear envelope 4. plasma membrane 5. chloroplast 6. RER 7. SER 8. Ribosomes 9. Mitochondria 10. golgi apparatus 11. vacuole 12. cytoplasm 13. cell wall 14. vescicle 15. lysosome
List 4 factors that need to be kept constant (within a narrow range) in animals.
1. pH of blood 2. Core temperature 3. Concentration of urea in blood 4. Concentration of sodium ions in blood
5. Describe a method using a colorimeter to investigate the effect of temperature (or ethanol concentration) on the permeability of cell membranes.
1. place 5 equally sized pieces of beetroot into a 100ml water bath of distilled water. 2. Increase the temperature of the bath by 10c intervals 3. Take samples of the water containing the beetroot five minutes after each temperature is reached 4. Measure the absorbance of each sample using a colorimeter using a blue filter. 5. Repeat with fresh beetroot pieces and calculate the mean.
How do you prepare a sample for staining?
1. placed on slide and allowed to air dry 2. then heat fixed by passing over a flame 3. the specimen will adhere to the microscope slide and will then take up stains
Describe 2 ways to sample plants (and sessile, or very slow moving, animals).
1. point quadrat 2. Frame quadrat
Give 3 examples of physiological adaptations
1. poison production- many reptiles produce venom to kill prey and plants to protect themselves form being eaten 2. Antibiotic production- some bacteria produce antibiotics to kill other species of bacteria in the surrounding area 3. Water holing- store water in the body to allow it to survive in dry climates.
Give 3 functions of plant cell walls
1. prevent cells bursting 2. allows turgidity 3. keep plants upright
Suggest whether fluorescent microscopy has a higher resolution than normal light microscopy
1. resolution the same 2. resolution limited by wavelength of light 3. fluorescence is light emitted 4. super resolved fluorescent microscopy has higher resolution
Describe the meaning of each of the symbols in the equation for calculating the correlation coefficient (test statistic) from a Spearman's rank correlation
1. rs= correlation coefficient 2. d= difference in ranks 3. n= number of pairs of data 4. If rs =0 there is not correlation 5. If rs<0 there is a negative correlation 6. If rs>0 there is a positive correlation
State where stem cells occur in plants and state which type of potency they have.
1. stem cells are present in Meristematic tissue (meristems)- found wherever growth is occuring in the plants- tips of roots and shoots. 2. Meristematic tissue is also located between the xylem and phloem- vascular cambium- they'll become cells in the phloem or xylem 3. Meristems are pluripotent
Outline how an ECG is recorded.
1. the heart muscles depolarises- loses electrical charge when it contracts and repolarises when it relaxes 2. An electrocardiograph records these changes in electrical charge using electrodes placed on the chest
describe sample preparation for electron microscopes
1. the inside of an electron microscope is a vaccum to ensure the electron beams travel in straight lines therefore samples need to be processed in a specific way 2. fixation using chemicals/ freexing 3. staining with heavy metals and dehydration with solvents 4. samples then set in resin and may be stained again 5. may be fractured to expose the inside and will the need to be coated with heavy metals
Describe the functions of the cytoskeleton in a cell
1. the microtubules and microfilaments support the cell's organelles, keeping them in position 2. they also help to strengthen the cell and maintain its shape 3. they are responsible for the transport of organelles and materials within the cell- e.g the movement of vesicles around the cell relies on cytoskeletal proteins 4. the proteins of the cytoskeleton can also cause the cell to move
Outline the structure and functions of the nuclear envelope
1. the nuclear envelope contains pores which allow molecules to move into and out of the nucleus 2. it also protects the nucleus from damage in the cytoplasm
what are the 4 levels at which genes are regulated?
1. transcriptional (genes can be turned on or off) 2. post-transcriptional (mRNA can be modified which regulates translation and the types of proteins produced) 3. translational (translation can be stopped or started) 4. post-translational (proteins can be modified after synthesis which changes their functions)
Explain why slide preparations need to be thin.
1. transmitted light is going through so it needs to be transparent or you won't see anything 2. you want to look at a single cell so you can measure it which you can't do if they overlap.
roles water plays in life
1. water is a reactant 2. water is a solvent 3. water transports substances 4. water helps with temperature control 5. water is a habitat
Water forms the basis of the stroma in chloroplasts and the matrix in mitochondria. Describe which properties of water make it such an important component of these particular organelles.
1. water is liquid which allows movement of substrates and enzymes which is necessary for reactions to occur 2. water is a polar solvent and substrates / enzymes / products are polar / ionic and water is the substrate for (some) reactions
Describe the structure of the trachea
1. wide tube supported by incomplete rings of strong flexible cartilage- stop from collapsing 2. Lined with a ciliated epithelium with goblet cells between and below the epithelial cells- secrete mucus onto lining of trachea to trap dust and micorgs that have escaped the nose lining. 3. Cilia beat and move the mucus along with trapped dirt and micorgs away from lungs
Describe the meaning of each of the symbols in the equation for calculating the t-value (the test statistic) from an unpaired Student's t-test.
1. x̄1 -mean of sample one x̄2- mean of sample 2 2. σ1- standard deviation of sample one σ2 -standard deviation of sample two 3. n1- population of sample one, n2- population of sample two
Describe the meaning of each of the symbols in the equation for calculating the t-value (the test statistic) from an unpaired Student's t-test
1. x̄1 -mean of sample one x̄2- mean of sample 2 2. σ1- standard deviation of sample one σ2 -standard deviation of sample two 3. n1- population of sample one, n2- population of sample two
Outline the structure and functions of the nucleolus
1.It is and area in the nucleus and is responsible for producing ribosomes 2. composed of proteins and RNA 3.RNA is used to produce ribosomal RNA (rRNA) which is then combined with proteins to form the ribosomes necessary for protein synthesis
State the properties and functions of starch
1.Starch is the main energy storage material in plants 2. Starch is insoluble in water- so it doesn't cause water to enter the cell by osmosis which would make them sell- good storage 3. Amylose- long unbranched chain of alpha-glucose the angles of the glycosidic bonds give it a coiled structure- making it compact so it's very good storage as it can fit a lot in a small space. 4. Amylopectin- long branched chain of alpha-glucose. its side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily. - it releases glucose quickly.
Define peripheral nervous system
1.This consists of all the neurones that connect the CNS to the rest of the body 2. These are sensory neurones which carry nerve impulses from the receptors to the CNS, and the motor neurones which carry nerve impulses away from the CNS to the effectors
When is water at it's highest density
4 degrees celsius
drosophila has...
8 how genes arranged in a single cluster on a single chromosome
Describe the meaning of the symbols: < < ~ ∝
< < much less ~ approximately equal to ∝ proportional
Define glomerulus
A bed of capillaries within the Bowman's capsule
Define the term "cell signalling".
A complex system of inter cellular communication.
Define homeodomain
A conserved motif of 60 amino acids found in all homeobox proteins. It is the part of the protein that binds to specific sites in DNA allowing the protein to act as a transcriptional regulator as it switches other genes on or off
Define the term tachycardia
A fast heart rhythm of over 100 beats per minute at rest
What is gene
A gene is a section of DNA that contains the complete sequences of bases (codons) to code for a protein.
Define the terms "polypeptide chain"
A molecule formed from more than 2 amino acids
Define the term condensation reaction
A reaction between two molecules resulting in the formation of a larger molecule and the release of a water molecule.
Define vaccine
A safe form of an antigen which is injected into the blood stream to provide artificial active immunity against a pathogen bearing the antigen
Define the term Frame quadrat
A square rigid structure of fixed size used to identify an area to be sampled. It is usually dived in to a grid of equal sections
State the products from oxidative phosphorylation and the fate of the products from oxidative phosphorylation.
ATP and water
Describe the roles of ATP and reduced NADP in the Calvin cycle.
ATP- provides energy to form TP from GP and energy to regenerate RuBP Reduced NADP- provides a hydrogen atom to form TP from GP-(needs to be H atom not H+ as if there is no electron preset a bond will not form).
Define community
All the populations of living organisms in a particular habitat
Explain the biological significance of Transparency
Allows photosynthesis to happen in aquatic environments . allows light to penetrate cells for photosynthesis in plants.
Describe the difference between alpha- and beta-glucose.
Alpha glucose has an -OH (hydroxyl group) that points "downwards", away from the ring, whereas the -OH on carbon 1 of beta glucose is above the ring.
Define hierarchical
Arranged so that each entity is subordinate to a different entity
State the 4 different types of pathogen and give 3 examples of each.
Bacteria- TB, bacterial meningitis, ringrot Virus- HIV/AIDS, influenza, tobacco mosaic virus Fungus- Black sigatoka, ringworm, Athlete's foot Protoctist- Potato/tomato blight, Malaria
Explain why "warm-blooded" and "cold-blooded" are inappropriate terms for endotherms and ectotherms.
Because all blood is warm- blood is never cold
Explain why it is easier for an oxygen molecule to diffuse across a membrane than a water molecule.
Because and oxygen molecule is non-polar so doesn't get repelled by the hydrophobic interior of the membrane.
Define the term "normal distribution curve" and give 4 characteristics of a normal distribution
Bell-shaped curve- with the peak at the mean Characteristics: Mean, median and mode are the same Curve is symmetrical around the mean 50% are below and 50% are above the mean Most values lie close to the mean
Explain with reference to their body shape why human beings are referred to as bilaterally symmetrical but jellyfish are radically symmetrical
Bilateral symmetry is along (single plane through) central axis e.g., two arms, two legs radial symmetry is along a plane at any angle through central axis e.g., tentacles around central axis
Define artificial immunity
Body is given immunity to a disease by intentional exposure to small quantities of it
Define summation
Build up of neurotransmitter in a synapse to sufficient levels to trigger an action potential
Carbohydrates- Name of macromolecule
Carbohydrate
Define the term reduction division
Cell division resulting in the production of haploid cells from a diploid cell- meiosis.
State the role of glycolipids in the membrane.
Cell markers or antigens and can be recognised by the cells of the immune system as self or non-self. Also stabilise the cell by forming hydrogen bonds with surrounding water molecules
Name the process by which cells communicate with each other
Cell signalling
Define the term "glycolipid",
Cell surface membrane lipids with attached carbohydrate molecules of varying lengths and shapes.
Define reaction centre
Chlorophyll a is located in the reaction centre, which is where the reactions involved in photosynthesis take place. The light harvesting system and reaction centre are collectively known as a photosytem.
7. Draw graph showing how substrate concentration affects the rate of an enzyme-controlled reaction if a competitive or non-competitive inhibitor is present. Explain the effect of competitive and non-competitive inhibitors on the Vmax of an enzyme-controlled reaction.
Competitive - the line is under the original and straighter but still reaches the same maximum. Non-competitive - the line is much lower and plateaus at a much lower point. So has a smaller maximum.
Describe the significance of the double stranded, complementary base paired nature of DNA for its function.
Complementary base pairing - allows itself to replicate easily It's long- stores a lot of information Coiled into double helix- stores a lot of info in a small space. It's stable- double helix and backbone
Define Bowman's capsule
Cup-shaped structure that contains the glomerulus and is the site of ultrafiltration in the kidney
Draw a diagram showing the flow of blood from the blood through the heart (include the names of the blood vessels adjoining the heart as well as whether the blood is oxygenated or deoxygenated and where the blood has come form or is going to).
Deoxygenated blood enters the right atrium of the heart from the upper body and head in the superior vena cava and from lower body in the inferior vena cava /The blood passes through the tricuspid valve into the right ventricle /This then contracts forcing the deoxygenated blood though the semilunar valves into the pulmonary artery, which takes it to the lungs /Then oxygenated blood form the lungs flows through the pulmonary vein into the left atrium /The blood passes through the bicuspid valves into the left ventricle/The left ventricle then contracts forcing the oxygenated blood through the semilunar valves into the aorta, it then travels round the whole body.
State the two main types of nucleic acid.
Deoxyribonucleic acid Ribonucleic acid
Describe how diffusion distance, SA, Volume and SA:Vol ratio vary with increasing organism size.
Diffusion distance increases as the organism gets bigger SA gets relatively smaller as the size increases SA:Vol ratio gets smaller as the size increases.
List the seven taxonomic groups, in order, from the broadest to the smallest.
Domain, kingdom, phylum, class, order, family, genus, species
Describe what is meant by a stop codon.
Don't code for any amino acids and signal the end of a sequence.
Draw a table to show the similarities and differences between, and advantages and disadvantages of, single and double circulatory systems.
Double: 1. Double circulatory systems are important because they ensure that we are giving our tissues and muscles blood full of oxygen, instead of a mixture of oxygenated and deoxygenated blood. 2. Requires more energy 3. The blood pressure can be high in the systemic circuit, while remaining low and safe in the pulmonary circuit Single: 1. Can only maintain one pressure- always low so doesn't damage capillaries. 2. Fish aren't as active so their system is sufficient for their needs
Explain why you would see more detail with an electron microscope than with a light microscope
Electron microscopes use electrons instead of light and electrons have a shorter wavelength than light which produces images with a higher resolution
Explain the biological significance of it being a good solvent for ionic and polar molecules
Enables transport of substances in solution. Metabolic reactions take place in solution
Draw a reaction to show how energy is released from ATP to provide energy for cellular activities.
Energy is stored in the phosphate bond, when energy is needed ATP is broken down to ADP and inorganic phosphate. Energy is released from the phosphate bond and used by the cell.
Define the term "inactive precursor enzyme" and explain why enzymes may be produced in this form.
Enzymes are sometimes synthesised as inactive precursors in metabolic pathways to prevent them causing damage to cells. Part of the precursor molecule inhibits its action as an enzyme. Once this part is removed the enzyme becomes active.
Lipids- Bond that links the building blocks together
Ester bond
Define receptor
Extrinsic glycoproteins that bind to chemical signals triggering a response by the cell
Define the term "limiting factor".
Factor that limits the rate of a process When in short supply it can cause a reaction to slow down
Define the term selection pressure
Factors that affect an organisms chance of survival or reproductive success
Alcoholic fermentation
Fermentation that results in the production of ethanol
Lactate fermentation
Fermentation that results in the production of lactate.
State some examples of organisms with each type of circulatory system.
Fish- Closed and single circulatory system Insect- Open circulatory system, (single probs) Human- Closed and double circulatory system
Explain what is meant by "fluid" and "mosaic" in the "fluid mosaic model of membrane structure".
Fluid- all phospholipids and membrane proteins can move around because they are not bonded to each other Mosaic- The phospholipids and the proteins form a pattern Fluid-Mosaic Model- model of the structure of a cell membrane in which phospholipids within the phospholipid bilayer are free to move and proteins o various shapes and sizes are embedded in various positions
Describe the arguments for and against the use of embryonic stem cells for research and medicine.
For: 1. Done well with regulation 2. Destroyed anyway 3. Relieve suffering 4. Help to stop the problem of the lack or organs for transplantation Against: 1. Rights of embryo 2. Might lead to human cloning 3. May cause cancer if differentiation process is not able to be controlled 4. Goes against religious and cultural beliefs
State the role of phospholipids in the membrane.
Forms the phospholipid bilayer. the phospholipid bi-layers are perfectly suited as membranes because the outer surface of the hydrophillic phosphate heads can interact with water.
Define tissue stem cell.
Found in specific areas e.g. bone marrow. They are multipotent but might be able to be artificially triggered to become pluripotent? They are how specialised tissues replace cells
Describe how guard cells are specialised for their funciton
Function- control the release and entry of gases. Structure: 1. Found in pairs with a gap between them to form a stoma- necessary for CO2 to enter plants 2. One side of the cell wall is thicker than the other- In the light, guard cells take up water into their vacuoles and become turgid- thin outer walls and thickened inner walls force them to bend outwards, opening the stomata. 3. When they lose water- less swollen- change shape and stoma close to prevent further water loss.
Describe what happens during the G1 stage of interphase
G1- The first growth phase- proteins from which organelles are synthesised are produced and organelles are duplicated- cell increases in size
Define gene mutation
Gene mutations occur in single genes or sections of DNA
Define the term gill plates
Gill plates are large stacks of gill filaments
Define endocrine gland
Group of specialised cells which secrete hormones
State the 3 levels of biodiversity.
Habitat, species and genetic biodiversity
Define the term "haploid"
Half the normal chromosome number - one chromosome of each type
Define the term "gamete"
Haploid sex cells produced by meiosis in organisms that reproduce sexually.
Draw and label a diagram of ADP.
Has 2 phosphate groups, the base adenine and ribose. ADP (adenosine diphosphate)
Draw a table to show typical habitat features for areas with low and high biodiversity.
High biodiversity: 1. A large number of successful species 2. More benign and not stressful environment with more ecological niches 3. Many species live in the habitat with few specific adaptations to the environment. 4. Complex food webs 5. Often change has a relatively small effect to the ecosystem as a whole
Describe how the level of activity of an organism is related to demand for oxygen and glucose.
Higher level of activity- more metabolic demands so more oxygen and glucose required.
Compare the neuronal and hormonal systems of cell signalling
Hormonal system 1. Communication is by chemicals called hormones 2. Transmission is by the blood system 3. Transmission is usually relatively slow 4. Hormones travel to all parts of the body, but only target organs respond 5. Response is widespread 6. Response is slow 7. Response is often long-lasting 8. Effect may be permanent and irreversible Nervous system 1. Communication is by nervous impulses 2. Transmission is by neurones 3. Transmission is very rapid 4. Nerve impulses travel to specific parts of the body 5. Response is localised 6. Response is rapid 7. Response is short-lived 8. Effect is temporary and reversible
Sugges hox genes roles in the development of certain tumours
Hox genes regulate the expression of other genes increased transcription of genes responsible for tumour development decreased expression of tumour suppressor genes
Define the term "secondary structure" of a protein
Hydrogen bonds forms between the -NH and -CO groups of amino acids in the same chain. This forms either an alpha helix coil or a beta pleated sheet
Draw a labelled diagram demonstrating the hydrolysis of peptide bonds.
Hydrolysis reaction - the breaking of peptide bonds using water
Draw a diagram to show the interconversion of ATP and ADP, the names of the types of reactions involved, where energy is released and the role of respiration.
Hydrolysis- ADP, P and energy is produced from ATP and H2O (energy is release for use by cells) Condensation- ATP and water is produced from ADP and P (energy is supplied from respiration)
Define the terms "hypothesis" and "null hypothesis"
Hypothesis- an idea or an explanation which then needs to be confirmed through experimentation Null hypothesis- The idea that there is no significant difference between specified populations and so any observed difference would be due to chance variation in a sample
Explain the biological significance of having a lower density when solid
Ice floats on water leaving liquid water beneath- so in cold temps ice forms and insulating layer on top of water so the water below doesn't freeze, and aquatic organisms like fish don't freeze and so can still move.High density provides upthrust supporting weight
Define the term "antigen" and differentiate between "self" and "non-self" antigens.
Identifying chemical on the surface of the cell that triggers an immune response. Self antigens are on your own cells and non-self antigens are on the cells of pathogens
Describe how the presence of cholesterol affects the properties of cell membranes.
If a cell gets hot phospholipids fall apart, if it's cold they will cramp together. Cholesterol grabs on to the fatty acid tails and holds them together when it's too hot and keeps them apart when to cold.
Suggest how autoimmune diseases may occur.
If the immune system can't recognise self antigens so treats them as foreign antigens and launches an immune response against organisms own tissues
Explain the need to maintain biodiversity in relation to the discovery of new medicines.
If we don't protect biodiversity some species may die out before we get a chance to study them. They could prove to be useful sources of medicine
Describe how one end of a polypeptide chain differs from the other end.
In a polypeptide one end has a NH2 amino group and the other end has a COOH group.
Explain why cells need to be compartmentalised and describe 3 examples of compartmentalisation within an animal cell
Incompatible reactions / catabolic and anabolic reactions require different conditions/ damage due to hydrolytic enzymes (e.g. nucleus, vesicle, lysosome, mitochondrion, Golgi body, endoplasmic reticulum, chloroplast)
Describe what is meant by indirect transmission of a pathogen, describe 2 clear examples (mode of transmission and pathogen) of each.
Indirect transmission: The pathogen travels from one individual to another indirectly Examples 1. Fomites- inanimate objects like socks can transfer disease- athlete's foot 2. Vectors- Mosquitoes transmit malaria
Define the terms "enzyme inhibitor"
Inhibitors are molecules that prevent enzymes from carrying out their normal function of catalyses or slow them down
Explain why insulin must be constantly secreted in order to maintain its effect
Insulin is broken down by enzymes in the cells of the liver so to maintain its effect it has to be constantly secreted
Define the term "glycoprotein".
Intrinsic membrane proteins with attaches carbohydrate molecules varying in lengths and shapes
Describe 4 ways in which proteins can be modified to provide post-translational control.
Involves modifications to the proteins that have been synthesised 1. Addition of non-protein groups such as carbohydrate chains, lipids or phosphates 2. Modifying amino acids and the formation of bonds such as disulfide bridges 3. Folding or shortening of proteins 4. Modification by cAMP( e.g in lac Operon cAMP binds to cAMP receptor protein)
Define the the term ventilation rate
Is the total volume of air inhaled in one minute
Define the the term residual volume
Is the volume of air left in your lungs when you have exhaled as hard as possible- can't measured directly.
Define the the term vital capacity
Is the volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath.
Define the the term tidal volume
Is the volume of air that moves into and out of the lungs with each resting breath.
Define the term isomer
Isomers are molecules that have the same molecular formula, but have a different arrangement
Define the term specific immune response
It is the slower than non-specific responses. However the immune memory cells mean it reacts very quickly to a second invasion by the same pathogen
Define the term "temperature coefficient, Q10" and state its usual value for enzyme controlled reactions.
It is the value for a reaction showing how much the rate of reaction changes when the temperature is raised by 10 Celsius. Before the optimum temp, a Q10 value of 2 means the rate has doubled, a value of 3 means the rate has trebled. Most enzyme controlled reactions have a Q10 value of 2.
Outline how a laser scanning lens works
It moves a single spot of focused light across a specimen (point of illumination). this causes fluorescence with the components labelled with a dye. The emitted light from the specimen is filtered through a pin hole aperture. Only light radiated from very close to the focal plane (the distance that gives the sharpest distance) is detected.
Define the term "primary structure" of a protein and describe how it is held together.
Its the sequence of amino acids in the polypeptide chain. Different proteins have different sequences of amino acids in their structure. Its held together by peptide bonds between the amino acids.
state what is meant by a synapse
Junction between one neurone and another (or neurone and effector cell)
Outline the structure and functions of the cytoskeleton in prokaryotic cells
Less complex than in eukaryotic cells cell as flagella which propel the cell by microfilaments
Lipids- Name of macromolecule
Lipid- triglyceride and phospholipids
Describe and explain how the melting point of a triglyceride would correlate with the length of the fatty acids it contained
Long chain fatty acids have a higher melting point as they have a longer hydrocarbon tail, so they can absorb more energy so more energy is required to break the bonds and melt it.
Define myofibril
Long cylindrical organelles found in muscle which are made of proteins and specialised for contraction
Draw a labelled diagram demonstrating how two molecules of glucose form a disaccharide in a condensation reaction, showing the location of a 1,4-glycosidic bond and from where a water molecule is generated.
Look at book
Describe the meaning of each of the symbols in the equation for calculating standard deviation
Look it up and remember how to use graphical calculator
Explain what is meant by "constant" in terms of homeostasis
Maintaining a relatively steady state around a narrow range of conditions
Why are beneficial mutations rare and suggest a process that beneficial mutations underpin?
Majority of mutations are silent idea that random change to protein structure is more likely to reduce function beneficial mutations increase chances of survival if environment changes surviving organisms reproduce and pass new alleles to offspring leading to evolution
Design an experiment to investigate one factor affecting phototropism in seedlings/coleoptiles.
Many different ways: 1. Germinate and grow seedlings in different conditions of dark, all-round light, and unilateral light. Observe, measure and record the patterns of growth. Time-lapse photography can give a good record of the changes as they take place 2. Germinate and grow seedlings in unilateral light with different colour filters to see which wavelengths of light trigger the phototropic response. 3. Repeat some of the classic experiments- cover the tips of coleoptiles, place auxin-impregnated agar jelly blocks or lanolin on decapitated coleoptiles, place auxin-impregnated agar blocks on one side only of decapitated coleoptiles.
Draw a table to compare the features of the marsupial mammalsand the placental mammal
Marsupial mammals- start life in the uterus, but then leave and enter the marsupium (pouch ) while they are still embryos.- moles have white-orange to match soil colour Placental mammals- Connects the embryo to it's mother's circulatory system in the uterus- reaches a high level of maturity before birth.- moles are grey to match soil 1. Example of convergent evolution, they resemble each other even though one is from australia and one from America, because they have adapted to fill similar niches 2. Have strong resemblance in overall shape, type of locomotion and feeding techniques 3. But have very different methods of reproduction
Name 3 examples of different habitats.
Meadow, woodland, streams and sand dunes
Explain how to calculate tidal volume from spirometer trace
Measure from the peak to the trough of the smaller waves.
State one measure that is used to indicate kidney disease
Measuring glomerular filtration rate
Define diabetes mellitus
Medical condition which affects a person's ability to control their blood-glucose concentration
Explain the role of meiosis in life cycles.
Meiosis forms gametes which contains half of the chromosome number of the parent cell- haploid. Cells formed by meiosis are geneticallly different because each new cell ends up with a different combination of chromosomes.
Define the terms "carrier protein",
Membrane proteins that play a part in the transport of substances through a membrane
Define myelinated sheath
Membrane rich in lipid which surrounds the axon of some neurones, speeding up impulse transmission
Define the term "end-product inhibition" and describe its usefulness in controlling metabolic pathways.
Metabolic pathways are regulated by end-product inhibition. A metabolic pathway is a series of connected metabolic reactions. The product of the first reaction takes part in the second. Each reaction is catalysed by a different enzyme. Many enzymes are inhibited by the product of the reaction they catalyse- product inhibition. End product inhibition- when the final product in a pathway inhibits an enzyme that acts earlier on in its pathway.
Describe the importance of the cytoskeleton in movements of vesicles.
Microtubules act as tracts for the movement of organelles including vesicles
State the site of the Krebs cycle within cells.
Mitochondrial matrix
State the site of the link reaction within cells
Mitochondrial matrix
Describe the role of mitosis and apoptosis in growth and development
Mitosis and differentiation create the bulk of body parts and then apoptosis refines the parts by removing unwanted structures
Describe the purpose of mitotic cell division.
Mitosis ensures that both daughter cells produces when a parent cell divides are genetically identical. It is needed in growth, replacement and repair of tissues as well as asexual reproduction.
List the 2 stages of the mitotic phase and outline what happens at each stage.
Mitosis- the cell divides Cytokenisis- the cytoplasm divides and two cells are produced
Define lymph
Modified tissue fluid that is collected in the lymph system
Define the term "phospholipid",
Modified triglyceride where one fatty acid has been replaces by a phosphate group.
What happens when mica is inserted on the shaded side of the shoot and it is exposed to unilateral light
Movement of chemical down shaded side is prevented by mica so no response
Explain how to calculate the chemical formula for a carbohydrate given the number of hexose sugars it is made up from
Multiply c6h12o6 by n=number of hexose sugars and then minus h2o*(n-1)
Give one example for each of natural active immunity, natural passive immunity, artificial active immunity and artificial passive immunity.
Natural active- immune after catching a disease Natural passive- baby becomes immune due to antibodies it receives form its mother though placenta/ breast milt Artificial active- Vaccination Artificial passive- Injected with antibodies from someone else
Define local circuits
Neural Circuits. Neurons never function in isolation; they are organized into ensembles or circuits that process specific kinds of information. ... Nerve cells that only participate in the local aspects of a circuit are called interneurons or local circuit neurons.
explain how synapses ensure impulses are only transmitted in one direction
Neurotransmitter receptors are only present on the postsynaptic membrane so can only cause depolarisation of this membrane resulting in action potential
Define the term expiration
Normal expiration ( breathing out or exhalation)- passive process
Draw a diagram showing the relative sizes of different cellular components.
Nucleus, mitochondria and chloroplast are big ribosomes are smallest vacuole in plant cell is the biggest
Define natural immunity
Occurs when the person is exposed to a live pathogen develops the disease and becomes immune as a result of the primary immune response- developed without intervention
Draw a table to show the similarities and differences between, and advantages and disadvantages of, open and closed circulatory systems.
Open: 1. Supply and disposal of materials is very slow 2. Blood flow can't be regulated 3. Blood flows at a slow velocity Closed: 1. Supply and disposal of materials is faster 2. Blood flow can be regulated 3. Blood flows at a fast velocity
Outline the levels of organisation of a multicellular organism (in order).
Organelle, Cell, Tissue, Organ, Organ system, Organism
Define the term convergent evolution
Organisms evolve similarities because the organisms adapt to similar environments or other selection pressures
Define obligate aerobe
Organisms that can only respire aerobically
Define facultative anaerobes
Organisms that can respire anaerobically or aerobically
Define the terms "passive transport"
Passive transport is a movement of substances across cell membranes without need of energy input.
Define the term "phagocyte" and state two examples of phagocytic cells.
Phagocytes are specialised white cells that engulf and destroy pathogens 1. Neutrophils 2. Macrophages
Define photosynthetic pigment
Pigment molecules absorb specific wavelengths of light and reflect others. Different pigments absorb and reflect different wavelengths and this is why they have different colours.
Describe cytokenisis in plant cells
Plant- 1. Have cell walls so can't form cleavage furrows. 2. Vesicles from the Golgi apparatus begin to assemble in the same place where the metaphase plate was formed. 3. The vesicles fuse with each other and the cell surface membrane dividing the cell into two. 4. New sections of cell wall then form along new sections of membrane.
State the difference between the triglycerides found in non-fish animals and those in plants and fish.
Plants have unsaturated triglycerides and animals have saturated triglycerides. don't know about fish
Define the term dicotyledonous plants (dicots)
Plants that produce seeds containing two cotyledons, which act as food stores for the developing embryo and form the first leaves when the seed germinates
Define the term xerophyte
Plants with adaptations that enable them to survive in dry habitats or habitats where water is in short supply
Define podocyte
Podocytes are specialised cells in the Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus
Describe the structure of a beta pleated sheet
Poly peptide chains can also lie parallel to each other with hydrogen bonds forming between them forming a sheet-like structure. The pattern formed by individual amino acids causes the structure to appear pleated.
Define the term stomata
Pores in the surface of a leaf or stem that may be opened and closed by guard cells
Suggest with reasons why cell theory was not fully developed before the mid 19th century
Prior to the mid-19th century microscopes were of too low a magnification to see and identify cells and cell components
Define glycogenolysis
Process in which glycogen stored in the liver and muscle cells is broken down into glucose which is released into the bloodstream
Define Schwann cell
Produce layers of membrane by growing around the axon many times- producing the myelin sheath
Define gluconeogenesis
Production of glucose from non-carbohydrate sources which is released into the blood stream
Define glycogenesis
Production of glycogen from glucose- decreases blood-sugar concentration
Define the term "quaternary structure" of a protein, and describe how it is held in place (include all the different possible bonds).
Quaternary structure results from the association of two or more individual proteins called sub-units. the interactions between the sub-units are the same as in tertiary structure except they are between different protein molecules rather than within one molecule.
Define RNA processing
RNA processing refers to any modification made to RNA between its transcription and its final function in the cell
Define the term gill lamellae or plates
Raised plates on the surface of gill filaments which in total create a large SA for gas exchange
State the two general ways in which sampling can be undertaken
Random and non-random
Outline how to randomly sample an area.
Random number tables or computers can be used 1. Mark out a grid on the grass using two tape measures laid at right angles 2. Use random numbers to determine the x coordinate and the y coordinate on your grid 3. Take a sample at each of the coordinate pairs generated
State Fick's law and show how the importance of each of the 4 features of efficient exchange surfaces can be explained by Fick's law.
Rate of Diffusion is proportional to (SA* Conc gradient)/ thickness of barrier (distance)
Noon
Rate of respiration < rate of photosynthesis
Dawn/dusk
Rate of respiration = rate of photosynthesis
Define anabolic reaction
Reactions of metabolism that construct molecules from smaller units - These reactions require energy from the hydrolysis of ATP
Define the term "exothermic reaction".
Reactions that release energy
Define the term genetic biodiversity
Refers to the variety of genes that make up a species
Define the term source
Regions of a plant that produce assimilates (e.g glucose) by photosynthesis or form storage materials e.g leaves, storage organs
Define exons
Regions of coding DNA or RNA
Define the term detoxification
Removal or breakdown of toxins
Describe the structure and function rRNA
Ribosomal RNA- forms the two subunits in a ribosome along with proteins. 2. The ribosome moves along the mRNA strand during proteins synthesis. 3. rRNA in the ribosome helps to catalyse the formation of peptide bonds between the amino acids.
Interpret a graph of aortic pressure
Rises when ventricles contract as blood is forced into aorta/Then it gradually falls but never below 12kPa - because of elasticity of walls creates a recoil action- temporary pressure
Compare the structure and function of the R and S ER
Rough ER has ribosomes attached and smooth ER does not have ribosomes attached rough ER protein synthesis (and modification) smooth ER lipid synthesis
Describe what happens during the S stage of interphase
S- synthesis phase- DNA is replicated in the nucleus
Q. Describe what happens during the S stage of interphase
S- synthesis phase- DNA is replicated in the nucleus
Draw and annotate a diagram of a motor neurone
See picture
State the difference between the function of a motor and a sensory neurone
Sensory neurones transmit impulses to the CNS / from receptor, motor neurones transmit impulses away from the CNS / to an effector
Define target tissue
Specific cells that hormones act on to stimulate a response
Define target tissue
Specific cells which hormones act on. Have receptors specific for the hormone
Outline the structure and functions of the centrioles
Structure 1. Small, hollow cylinders, made of microtubules (tiny proteins cylinders) 2. found in animal cells but only some plant cells Function 1. involved with the separations of chromosomes during cell division
Define the term "chromosome"
Structures of condensed and coiled DNA in the form of chromatin. Chromosomes become visible under the light microscope when cells are preparing to divide.
State the form in which carbohydrates are transported in plants.
Sucrose
Define the term gene pool
Sum total of all the genes in a population at a given time
Define the term non-cyclic photophosphorylation
Synthesis of ATP and reduced NADP involving PS1 and PS2
Define the term cyclic photophosphorylation
Synthesis of ATP involving only photosystem 1
the membrane of a vacuole in a plant cell is called the
TONOPLAST
State the difference between the peripheral and the central nervous system
The CNS is the brain and the spinal cord, the PNS is all other neurones
Define the term template strand
The antisense strand of DNA that acts as template during transcription so that the complementary RNA strand formed carries the same code for a protein as the DNA sense strand.
Define the term hydrolysis reaction
The breakdown of a molecule into two smaller molecules requiring the addition of a water molecule.
Define the term antigen-antibody complex
The complex formed when an antibody binds to an antigen
Define sarcoplasm
The cytoplasm of muscle cells
What are smear slides?
The edge of the slide is used to smear the sample which creates a thin, even coating on another slide. a cover slip is then placed over the sample
Define the term "activation energy"
The energy required to initiate a reaction
Define pulmonary circulation
The flow of blood away from the heart through the lungs where oxygenation occurs and then returns to the heart again
Define synaptic cleft
The gap which separates the axon of one neurone from the dendrite of the next neurone
Define biotic factor
The living components of an ecosystem
Define the term trachea
The main airway, supported by incomplete rings of cartilage, which carries warm moist air down form the nasal cavity into the chest.
Define the term nucleotide
The monomers used to form nucleic acids. Made up of pentose monosaccharide, a phosphate group and a nitrogenous base.
Define transpiration stream
The movement of water through a plant from the roots until it is lost by evaporation from the leaves
Define the term bivalent
The name for two homologous chromosomes that have paired up in prophase 1 of meiosis.
Define the term filtration pressure
The net driving force which pushes fluid into tissue spaces and out of vascular sites. The net result between capillary osmotic pressure and hydrostatic pressure.
Define the term reflex arc
The pathway of neurones involved in a reflex action is known as a reflex arc
Draw a nucleotide showing the structure of the pentose sugar and where the phosphate group and nitrogenous base attach using the standard system for numbering the carbons in the sugar.
The phosphate group attaches to the 5' (prime) carbon. The base attaches to the 1' carbon of the pentose.
Draw and label a diagram to show how nucleotides can link together to form polynucleotides (including the production of water).
The phosphate group of the 2nd nucleotide bonds to the hydroxyl group of the 3' carbon of the pentose sugar in the 1st nucleotide to form a phosphodiester bond. This forms a strong, long sugar-phosphate backbone. This releases a water moleucules
Define the term allosteric site
The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of the enzyme and influencing its ability to be active.
Explain how comparative anatomy provides evidence for evolution
The presence of homologous structures provides evidence for divergent evolution.- describes how, from a common ancestor, different species have evolved.
Define the term hydrostatic pressure
The pressure created by water in an enclosed sytem
Define the term natural selection
The process by which organisms best suited to their environment survive and reproduce, passing on their characteristics to their offspring through their genes
Define the terms "phagocytosis"
The process by which white blood cells called phagocytes recognise non-self cells, engulf them, digest them within a vesicle called a phagolysosome
Define the term oxidative phosphorylation
The process where energy carried by electrons from coenzymes (NAD and FAD) is used to make ATP
Define the term assimilates
The products of photosynthesis that are transported around a plant e.g sucrose
Define the term "species".
The smallest and most specific taxanomic group. A species are a group of organisms that are able to reproduce and produce fertile offspring.
Define tissue fluid
The solution surrounding the cells of multicellular organisms
what does hypertonic and hypotonic mean?
The solution with the lower concentration is termed hypotonic
Define the term buccal cavity
The space behind the mouth in a fish.
Define sarcoplasmic reticulum
The specialized endoplasmic reticulum of muscle fibres that functions especially as a storage and release area for calcium.
Define the term "rate of reaction".
The speed at which a chemical reaction proceeds.
Define phylogeny
The study of living organisms based on their evolutionary relationships
Define histology
The study of the microscopic structure of tissues
Q. Describe the "lock and key" hypothesis of enzyme action.
The substrate fits into the enzyme in the same way a key fits into a lock- the active site and substrate have a complementary shape.
Define haemolymph
The transport medium of blood in insects
Define the term polar
The uneven distribution of charge, which results in the atoms within a molecule to have opposing charges. eg, one having a partial negative charge and one having a partial positive charge
Define the term biodiversity
The variety of living organisms present in an area
Define the terms "protoplast"
The whole cell excluding the cell wall
Explain why the zinc ion that forms an important part of the structure of carbonic anhydrase (an enzyme necessary of the metabolism of carbon dioxide) is called a prosthetic group not a cofactor or coenzyme.
The zinc ions are a permanent part of the enzyme's active site.
Describe the hydrogen bonds in the tertiary structure
These weak bonds form between slightly positively- charged hydrogen atoms in some R-groups and slightly negatively-charged atoms in other R-groups on the polypeptide chains.
Explain why a DNA molecule has equal amounts of adenine and thymine and equal amounts of cytosine and guanine.
They always pair up together, so you can't have one without the other.
Define the term "non-specific defences".
They are always present or activated very rapidly Defends against pathogens in the same way.
Describe the structure of sterols/cholesterol.
They are complex alcohol molecules based on a carbon ring structure attached to a hydrocarbon tail. The ring has a polar hydroxyl group attached to it which is hydrophillic and the rest is non-polar and hydrophobic.
Explain why steroid hormones can easily cross a membrane by simple diffusion.
They are lipid derived hormones
Draw a labelled diagram showing the basic structure of a phospholipid.
They have the same structure as a triglyceride apart from one of the fatty acid tails is replaced by a phosphate group which is on the opposite side of the glycerol.
Describe the "induced-fit" hypothesis of enzyme action.
This helps to explain why enzymes are so specific and only bound to one particular substrate. The substrate doesn't only have to be the right shape it has to make the active site change shape in the right way. The active site changes shape slightly when the substrate binds to it, making it a tighter fit.
Define the term line transect
This involves marking out a line along the ground between two poles and taking samples at specified points.
Define non-overlapping
This means that successive triplets are read in order. Each nucleotide is part of only one triplet codon.
Draw and label a diagram showing the arrangement of the structures involved in breathing.
Trachea divides into bronchi which divide into bronchioles which have alveoli. two lungs and a diaphragm under them. ribs over the lungs with intercostal muscles in between
Draw a table to compare the effects of external solutions, with different water potentials in comparison to the water potential in an animal cell.
Water Potential of external solution compared to cell solution: Higher (hypotonic) - water enters the cell- swells and bursts (cytolysis) Equal (isotonic)- no net movement of water- no change Lower (hypertonic) - water leaves the cell- shrinks (Crenated)
Define dissociation
When oxygen leaves haemoglobin it is referred to as dissociation
Define polarised
When there is a difference in mV inside a cell compared to outside a cell
Name the two types of transport vessels in vascular bundles.
Xylem and Phloem
Define the term antibody
Y-shaped glycoproteins made by B ells of the immune system in response to the presence of an antigen
Carbohydrates- Is the macromolecule a polymer
Yes
Proteins- is the macromolecule a polymer
Yes
What is a mutagen?
a chemical, physical or biological agent which causes mutations
Paracetamol>>>
a common painkiller broken down by the liver
Describe the beam splitter in a LSCM
a dichronic mirror, which only reflects one wavelength from the laser but allows other wavelengths to pass through
Discuss coolanr nature of water
acts as a coolant helping to buffer temeprature changes during chemical reactions because of the large amounts of energy required to overcome hydrogen bonding
harmful substances removed from the blood by the liver:
alcohol paracetamol insulin
why does embedding with resin take place?
allows thin slices to be obtained
the bubbles that get trapped under the cover slip as you prepare a slide for light microscopy...
are artefacts
liver lobules:
basic functional units of the liver made of cells called hepatocytes that are arranged in rows radiating out from the centre
How are harmful substances broken down in the liver?
blood runs through the sinusoids past the hepatocytes that remove harmful substances and o2 from the blood and break them down into less harmful substances that can re enter the blood
Describe similarities and differences between a human cell and a plant root cell
both have three named organelles (e.g. nucleus, cell surface membrane, mitochondria, ribosomes, Golgi body, endoplasmic reticulum) only plants have two named organelles (e.g. chloroplasts, cell wall, large (central) vacuoles) (1) / centrioles present in animal cells but not flowering plants
the hepatic portal vein...
brings blood from the duodenum and ileum so its rich from products of digestion. substances can be filtered out and broken down straight away
How can potential damage to specimen be avoided when prepareing a squash slide?
by squashing the sample between two microscope slides
How can specific features be targeted and therefore studied by confocal microscopy with much more precision than when using staining and light microscopy?
by using antibodies with fluorescent tags
Affects of excess paracetamol in the blood?
can lead to liver and kidney failure
compensation point
carbohydrate produced by photosynthesis equal to carbohydrate used in respiration
State the elements present in lipids (and the additional element needed to make phospholipids).
carbon, oxygen, hydrogen, phosphor
what does the homeodomain protein do?
causes genes to switch on or off
fixing =
chemicals like formaldehyde are used to preserve specimens in as near-natural state as possible
Name 3 types of photosynthetic pigments found in the antennae complex.
chlorophyll b, xanthophylls and carotenoids.
excess amino acids can be...
damaging to the body, so they must be used by the body (to make proteins) or broken down and excreted
Why does respiration rate increase in the daytime?
daytime temperatures generally higher than night time rate of respiration increases with increased temperature as its enzymes are temperature-dependent
Where are Pacinian corpuscles located?
deep within your skin and are must abundant in the fingers and the soles of the feet. also found within joints enabling you to know which joints are changing direction
draw a diagram of a triglyceride with elements
draw it on paper
Secretory cells which release hormones or enzymes have more...
endolasmic reticulum than cells that do not release proteins
what are nephrons?
functional unit of the kidney (long tubules along with the bundle of capillaries)
what controls morphgogenesis and differentiation?
gene expression
Proteins- examples of functions
globular proteins- regulate many processes such as chemical reactions, immunity, muscle contractions. conjugated proteins Fibrous Proteins- make strong, long molecules- structure
what is the preferred respiratory substrate of escherichia coli and many other bacteria?
glucose as it is easier to metabolise
What is the process of Detoxification?
harmful substances are broken down into less harmful compounds that can then be excreted from the body
Insulin>>>
hormone that controls blood glucose concentration.
Define magnification
how much bigger an image form a microscope is compared to the specimen
Why is the heart called a "Double Pump"?
it consists of two muscular pumps/the right side pumps deoxygenated blood to the lungs/left side pumps oxygenated blood to the rest of the body
Water is stable... discuss
it does not change temperature or become a gas easily (HLHC) providing a constant environment
How does a Laser scanning confocal microscope produce high resolution images?
light emitted from other parts of the specimen would reduce the resolution and cause blurring therefore this unwanted radiation does not pass through the pinhole and is not detected. a laser is used instead of light to get higher intensities which improves illumination. also very thin sections are used and light from elsewhere is removed
state the transformation that takes place in a cone cell.
light energy is converted into a nervous impulse/action potential
One limitation of confocal microscopy is that it can not be used for deep tissue imaging. Suggest why
light penetration (of sample) is limited
Excess amino acids are broken down by the
liver
Draw a simplified molecule of alpha- and beta-glucose.
look at book
Draw a table comparing the use and properties of light, SEM, TEM and laser scanning confocal microscope.
look at book
Produce a labelled and annotated high power drawing of a named number of cells using a light microscope.
look at book
Produce a labelled and annotated low power tissue plan using a light microscope.
look at book
State the features of the images produced from light, SEM, TEM and laser scanning confocal microscopes.
look at book
Draw and label a diagram of a chloroplast
look at book and draw it
State the three types of RNA.
mRNA, tRNA and rRNA.
State the magnification formula and represent the magnification formula in a triangle diagram.
magnification= size of image/ acutal size of object
Discuss how the structure of microfilaments and microtubules means these compartments of the cytoskeleton are involved in the movement of cells but the intermediate fibres are not
microfilaments composed of actin / (actin is) contractile and microtubules composed of tubulin tubulin polymerises/ contraction and polymerisation lead to change in length of filaments change in length (of filaments) results in movement of cell intermediate fibres have fixed length for stability
Calculate the mitotic index of a sample of dividing cells.
mitotic index= number of cells with condensed chromosomes/ total number of cells * 100
Explain how to convert measurements from one unit into another.
mm-> um x1000 mm-> nm x 1,000,000 um-> mm /1000 um-> nm x1000 nm-> mm / 1,000,000 nm-> um / 1,000
Define abiotic factor
non-living conditions in a habitat
What is the Pax6 gene?
one of the homeobox genes. when mutated it causes a form of blindness in many species due to underdevelopment of the retina (humans, mice and fruit flies)
CHLOROPLASTS
organelles responsible for photosynthesis in plant cells. double membrane structureand the fluid is enclosed in chloroplast called the stroma. also have internal network of membranes which form flattened sacs called thylakoids.
why does dehydration take place?
prevent vaporisation of water in vacuum as vaporisation would damage sample
Why must a cover slip be placed onto a wet mount at an angle?
reduce / prevent air bubbles being trapped
explain the purpose of the pinhole aperture in confocal microscopy
scattered light / light from outside the focal plane is eliminated and reduces blurring which increases resolution
If vacuoles appear in animal cells they are...
small and transient (not permanent)
Outline the structure and functions of ribosomes in prokaryotic cells
smaller 70s and free in cell
What types of samples require squash slides?
soft samples e.g root tip squashes are used to look at cell division
What is a wet mount?
specimens are suspended in a liquid such as water or an immersion oil. a cover slip is placed on from an angle
why does fixation take place?
stabilise sample / prevents decomposition
The hepatic artery...
supplied the liver with oxygenated blood from the heart, so the liver has a good supply of o2 for respiration, providing lots of energy
the bile duct...
takes bile to the gall bladder to be stored
The hepatic vein...
takes deoxygenated blood away from the liver
Where does selective reabsorption occur?
takes place as the filtrate flows through the proximal convoluted tubule through the loop of henle and along the distal convoluted tube
How can drugs affect the activity of regulatory genes example?
thalidomide - given to pregnant women to treat morning sickness - later discovered that prevented the normal expression of a particular hox gene - resulted in birth of babies with shortened limbs
Beneficial mutation of lactose
the ability to digest lactose (sugar in milk) relatively recent mutation. the ability to drink milk and process lactose as an adult helps prevent diseases such as osteoporosis
What happens after the hepatocytes break down the harmful substances?
the blood runs to the central vein and the the central veins from all the lobules connect up to form the hepatic vein
Flagellum and basal body
the flagellum is attached to the cell membrane of a bacterium by a basal body and rotated by a molecular motor. the basal body attched the filament comprising the flagellum to the cell-surface membrane of a bacterium. a molecular motor causes the hook to rotate giving th filament a whip like movement which propels the cell
changes in ultrastructure of cells are seen as ...
the loss of continuity in membranes, distortion of organelles and empty spaces in the cytoplasm of cells
Describe the process of Deamination
the nitrogen-containing amino groups are removed from any excess amino acids forming ammonia and organic acids
What happens to the organic acids produced by deamination?
the organic acids are respired to give atp or converted to carbohydrate and stored as glycogen
State the property that each end of the phospholipid has.
the phosphate group is charged and is hydrophilic - attracts water molecules Fatty acid tails are non- polar and hydrophobic
What is capillary action?
the process by which water can rise up a narrow tube against the force of gravity
what are the further divisions of the autonomic nervous system
the sympathetic and parasympathetic nervous system
What happens to the urea produced in the Ornithine Cycle?
the urea is released from the liver into the blood. The kidneys then filter the blood and remove the urea as urine which is excreted from the body
Explain how volume is related to demand and surface area is related to supply. Also explain why supply meeting demand requires adaptations as organisms increase in size
1. A larger volume means a larger volume of cells which means a higher metabolic demand. 2. Surface area gives a surface for the exchange of nutrients and gases- larger SA means a faster supply 3. When SA:Vol ratio is so small that the organism cannot meet its metabolic demands adaptations are required to develop a more efficient transport system.
Explain how volume is related to demand and surface area is related to supply. Also explain why supply meeting demand requires adaptations as organisms increase in size.
1. A larger volume means a larger volume of cells which means a higher metabolic demand. 2. Surface area gives a surface for the exchange of nutrients and gases- larger SA means a faster supply 3. When SA:Vol ratio is so small that the organism cannot meet its metabolic demands adaptations are required to develop a more efficient transport system.
Explain why measuring species diversity allows us to obtain information about the stability of an ecosystem or the degree of pollution in an ecosystem.
1. A low biodiversity would suggest an unstable and polluted ecosystem. 2. As only a few organisms are present, so it must be an extreme environment as only a few species have survived in it.
Describe how monoclonal antibodies to hCG are produced
1. A mouse is injected with hCG so it makes the appropriate antibody 2. The b-cells that make the required antibody are then removed from the spleen of the mouse and fused with a myeloma, a type of cancer cell which divides very rapidly 3. This new fused cell is known as a hybridoma 4. Each hybridoma reproduces rapidly resulting in a clone of millions of 'living factories' making the desired antibody. 5. These monoclonal antibodies are collected, purified and used in a variety of ways
Define the term "refractory period" and explain its importance for the conduction of the action potential
1. A short period of time when the axon cannot be excited again, known as the refractory period 2. During this time the voltage-gated sodium ion channels remain closed preventing the movement of sodium ions into the axon 3. It is important because it prevents the propagation of an action potential backwards along the axon as well as forwards 4. The refractory period makes sure action potentials are unidirectional and it also ensures that action potentials do not overlap and occur as discrete impulses
Describe how histone modification can affect gene expression
1. DNA coils around histones because they are positively charged and DNA is negatively charged 2. Histones can be modified to increase or decrease the degree of packing (or condensation) 3. The addition of acetyl groups (acetylation) or phosphate groups (phosphorylation) reduces the positive charge on the histones and this causes DNA to coil less tightly allowing certain genes to be transcribed 4. The addition of methyl groups (methylation) makes histones more hydrophobic so they bind more tightly to each other causing DNA to coil more tightly and preventing transcription of genes
Describe the process of Transcription
1. DNA gene copied into mRNA- H bonds break 2. Free/activated RNA nucleotides line up by complementary base pairing to one template/sense strand 3. Catalysed by RNA polymerase 4. mRNA moves out of nucleus through nuclear pore and attaches to ribosome
Outline the structure of the insect gas exchange system and describe the way oxygen reaches the body cells.
1. Air moves into the tracheae through pores on the surface called spiracles. 2. O2 travels down the conc gradient towards the cells. 3. CO2 from the cells moves down its own conc gradient towards the spiracles to be released into atomsphere. 4. The tracheae branch off into smaller tracheoles which have thin permeable walls and go to individual cells.- they also contain fluid which oxygen dissolves in 5. The oxygen then diffuses from this fluid into body cells- CO2 diffuses in the opposite direction.
Explain how alcohol affects the nervous system
1. Alcohol binds to GABAA receptors 2. this changes shape of receptor allowing more neutrotransmitter (GABA) to bind 3. this increases activity of the neurotransmitter 4. GABA decreases the activity of the brain by preventing nervous transmission
Describe the process of alcoholic fermentation
1. Alcoholic fermentation is not a reversible process like lactate fermentation 2. Pyruvate is first converted to ethanal, catalysed by the enzyme pyruvate decarboxylase 3. Ethanal can then accept a hydrogen atom from reduced NAD, becoming ethanol 4. The regenerated NAD can then continue to act as a coenzyme and glycolysis can continue 5. This is not a short-term process can can continue indefinitely in the absence of oxygen 6. Ethanol is a toxic waste product to yeast cells and they are unable to survive if ethanol accumulates above approximately 15%
Explain why stem cell treatment is not likely to be suitable for treating Type 2 diabetes
1. All body cells faulty in type 2, not possible to replace all 2. In type 1 it is only one type of cell so it may be possible to replace that cell type using stem cells that are programmed to differentiate into the β cells in the pancreas.
Name the nitrogenous waste products in mammals, fish, birds and insects
1. All mammals produce urea as their nitrogenous waste 2. Fish produce ammonia 3. Birds and insects produce uric acid
Give examples of reducing sugars
1. All monosaccharides 2. Some disaccharide—maltose and lactose
What substances are reabsorbed in the proximal convoluted tubule
1. All of the glucose- by active transport 2. All amino acids- by active transport 3. All vitamins- by active transport 4. All hormones - by active transport 5. All mineral ions- by active transport 6. 85% water follows by osmosis 7. 85% sodium chloride
Describe 2 ecological reasons for maintaining biodiversity.
1. All organisms are interdependent on others for survival. The removal of one may have a significant effect on others, for example a food source or a place to live may be lost. e.g plants rely on bees for pollination, declining bee population would decrease crop yield. 2. Keystone species affect many other organisms in an ecosystem and help to determine the species richness and evenness in the community. When removed the habitat is drastically changed- other species are affected and some may disappear altogether.
Explain how changing temperature affects the concentration of RuBP, TP and GP in the Calvin cycle.
1. All reactions in the Calvin cycle are catalysed by enzymes 2. At lower temperatures enzyme and substrate molecules have less kinetic energy resulting in fewer successful collisions and a reduced rate of reactions. 3. This means there will be lower concentrations of GP, TP and RuBP. 4. The same effect will be seen at high temperatures as enzymes will be denatured.
Describe the structure of the bronchioles
1. Bronchi divide to make many small bronchioles. 2. Smaller bronchioles have no cartilage rings 3. Walls of bronchioles contain smooth muscle - when it contracts the bronchioles constrict, when relaxes they dilate. - this changes amount of air reaching the lungs 4. Lined with layer of flattened epithelium - some gaseous exchange can happen.
State the molecules required for the link reaction
1. CO enzyme A 2. pyruvate 3. NAD
What is required for the light independent cycle to progress
1. CO2- atmosphere 2. ATP- Light dependent stage 3. Reduced NADP- Light dependent stage 4. RuBP- regenerated in the Calvin cycle
State the products for the link reactions
1. CO2- diffuse or used in photosynthesis 2. Reduced NAD- oxidative phosphorylation 3. Acetyl CoA- delivers acetyl groups to Krebs cycle
Show the chemical symbol and biological processes Calcium ions are responsible for
1. Ca2+ 2. Involved in the transmission of nerve impulses and the release of insulin 3. Acts as a co-factor for many enzymes 4. Important in bone formation
Name two molecules produced by plants to limit the spread of the pathogen.
1. Callose 2. Lignin- added to callose making the mechanical barrier to invasion even thicker and stronger
Describe 4 ways callose is used to limit the spread of a pathogen.
1. Callose gets deposited between the plant cell wall and plasma membranes after initial attack make it harder for pathogens to enter cells. 2. Large amounts of callose continues to be deposited in cell walls after the initial infection and lignin is added- makes it stronger 3. Callose blocks sieve plates in the phloem, sealing off the infected part and preventing the spread of pathogens 4. Callose deposited in the plasmodesmata between infected cells and their neighbours which may limit the spread of pathogens between cells
Describe the process of DNA replication in a series of bullet points.
1. DNA helicase (enzyme) breaks hydrogen bonds between the two polynucleotide DNA strands. The helix unzips to form two single strands. 2. Each original single strand acts as a template for a new strand. Free floating DNA nucleotides join to the exposed bases on each original template strand by complementary base pairing. A-T C-G. 3. The nucleotides on the new strand are joined together by DNA polymerase. This forms a sugar-phosphate backbone. H bonds from between the bases on the original and new strand. 4. The strands twist to form a double-helix. Each new DNA molecule contains one strand from the original DNA molecule and one new strand.
State 3 ways in which the body gains water and 4 ways in which water is lost from the body
(Gains water) 1. Respiration in cells 2. Food 3. Drink (Water losses) 1. Exhaled air 2. Faeces 3. Sweat 4. Urine
Give two examples of detoxification by the liver
(Hydrogen peroxide) 1. Breakdown of hydrogen peroxide (a by-product of various metabolic pathways in the body) 2. Hepatocytes contain the enzyme catalase, one of the most active known enzymes that splits the hydrogen peroxide into oxygen and water Ethanol 1. Hepatocytes contain the enzyme alcohol dehydrogenase that breaks down the ethanol to ethanal 2. Ethanal is then converted to ethanoate which may be used to build up fatty acids or used in cellular respiration
Following the release of ADH, what effect does cAMP have in osmoregulation
(cAMP sets of a cascade of events) 1. Vesicles in the cells lining the collecting duct fuse with the cell surface membrane on the side of the cell in contact with the tissue fluid of the medulla 2. The membranes of these vesicles contain protein- based water channels (aquaporins) and when they are inserted into the cell surface membrane, they make it permeable to water 3. This provides a route for water to move out of the tubule cells into the tissue fluid of the medulla and the blood capillaries
Describe how, and explain why, DNA replication occurs by continuous replication of one strand and discontinuous replication of the other strand.
1. DNA polymerase always moves along the template strand in the same direction. 2. It can only binds to the 3' end so travels in 3' to 5' direction (Of original strand). 3. This is not a problem for the leading strand of DNA as this travels in the 3' to 5' direction- so has continuous replication 4. But lagging strand travels in 5' to 3' direction, so polymerase can't attach the nucleotides continuously- discontinuous replication. 5. This results in DNA being produced in sections which have to be joined
Draw a table to show the similarities and differences between the nucleotides of DNA and RNA.
1. DNA= deoxyribose, RNA= ribose 2. DNA and RNA both have adenine and guanine purines 3. DNA and RNA both have cytosine BUT DNA= Thymine, RNA= Uracil pyradimines
Outline how an ectotherm regulates its internal temperature using physiological responses
1. Dark colours absorb more radiation than light colours, lizards in cold climates tend to be darker coloured than lizards in warmer climates- warm 2. Some alter their heart rate to increase or decrease metabolic rate
Draw a table to compare the action of gibberellins and auxins in the growth of stems.
1. Example molecules: A- IAA G- Gibberellic acid GA 1 2. Effect on stem length: A- increase G- increases 3. pH of molecule: A- acidic G- acidic 4. Effect on cell length: A- increase G- increase 5. Effect on cell division: A- none G- increase 6. Effect on cell wall: A- loosens G- loosens 7. Location where they stimulate growth: A- lateral buds, apical meristems G- stems at internodes.
Describe the difference between excitatory and inhibitory neurotransmitter
1. Excitatory- these neurotransmitters result in the depolarisation of the postsynaptic neurone. If the threshold is reached in the postsynaptic membrane an action potential is triggered. Acetylcholine is an example 2. Inhibitory- These neurotransmitters result in the hyperpolarisation of the postsynaptic membrane. This prevents an action potential being triggered. Gamma-aminobutyric acid is an example
Describe and explain 4 ways that heat is transferred between an organism and their environment.
1. Exothermic chemical reactions 2. Latent heat of evaporation- objects cool down as water evaporates from a surface 3. Radiation- the transmission of electromagnetic waves to and form the air, water or ground 4. Convection- the heating and cooling by currents of air or water 5. Conduction- heating as a result of the collision of molecules.
Describe how a plant can grow towards light
1. Exposure to light that is more strong on one side than the other causes auxin to move laterally across the shoots, so there is a greater concentration on the unilluminated 2. This in turn stimulates cell elongation and growth on the dark side, resulting in the observed growth towards the light 3. Once the shoot is growing directly towards the light, the unilateral stimulus is removed. The transport of auxin stops and the shoot then grows straight towards the light.
Explain why the conditions critical to an organism change (use 4 examples from the internal environment and 4 examples from the external environment).
1. External- humidity, external temperature, light, new or sudden sound 2. Internal- Blood-glucose conc, internal temperature, water potential, cell pH conditions change 1. Substances used up in metabolic reactions 2. Waste products are constantly being produced 3. Metabolisms change to meet changing demands of the organism 4. Intake varies overtime 5. Environmental conditions change
Define receptor
1. Extrinsic glycoproteins that bind chemical signals, triggering a response by the cell 2. Detect changes in the internal and external environment of an organism
Draw a diagram to outline the transfer of liquid between the blood, tissue fluid and lymph in the body.
1. From the blood it goes to the tissue fluid and most gets reabsorbed to the blood 2. The liquid that doesn't drains off to the lymph where it gets transported in lymph vessels back to the blood plasma
State 3 examples of checkpoints in the cell cycle, where they occur and what is checked at each checkpoint.
1. G1 checkpoint - at the end of G1 before entry into S phase - checks- cell size, correct nutrients, growth factors and DNA damage 2. G2 checkpoint - at the end of G2 phase before the start of the mitotic phase - checks - Cell size, all DNA replicated correctly, DNA damage 3. Spindle assembly checkpoint - at the point in mitosis where all the chromosomes should be attached to spindles and have aligned - checks - chromosome attachment to spindle
Suggest why Gram-Negative infections are more difficult to treat than Gram-positive infections?
1. Gram negative have thinner cell wall 2. penicillin disrupts cell wall formation 3. less cell wall formation (in gram negative) / membrane (around gram negative) prevents entry of penicillin
State 3 examples of sources
1. Green leaves and stems 2. Storage organs such as tubers and tap roots 3. Food stores in seeds when they germinate
Describe, and explain the importance of the steps in the isolation and purification of DNA by precipitation.
1. Grind sample- breaks cell wall 2. Mix with detergent- breaks cell membrane, releasing cell contents into solution 3. Add salt- breaks H bonds between the DNA and water molecules. 4. Add protease enzymes- break proteins associated with DNA in nuclei. 5. Add layer of alcohol on top of sample- causes DNA to precipitate out of solution 6. White strands will form- DNA- between layer of sample and layer of alcohol
List 4 roles of mitotic cell division.
1. Grow new cells to repair damage 2. grow new cells 3. Grow new cells to replace sheded skin cells 4. Asexual reproduction
Describe what auxins are and what their effect depends on
1. Growth stimulants produced in plants e.g. indoleacetic acid IAA 2. Small quantities can have powerful effects 3. They are made in cells at the tip of the roots and shoots and in the meristems 4. Auxins can move down the stem and up the roots both in the transport tissue and from cell to cell 5. The effect of auxin depends on its concentration and any interactions it has with other hormones.
Show the chemical symbol and biological processes Hydrogen ions are responsible for
1. H+ 2. Affects the pH of substances 3. Catalyses reactions 4. Important for photosynthesis reactions that occur in the thylakoid membranes inside.
Show the chemical symbol and biological processes Hydrogencarbonate ions are responsible for
1. HCO3- 2. Acts as a buffer which helps to maintain the pH of the blood
Describe the characteristic features of Archaea
1. Have 70s ribosomes 2. RNA polymerase of different organisms contain between 8 and 10 proteins
Describe the characteristic features of Eukarya
1. Have 80s ribosomes 2. RNA polymerase contains 12 proteins
Describe how companion cells are adapted for their function.
1. Have many infoldings in their cell membrane to give an increased surface area for active transport of sucrose into the cell cytoplasm. 2. They also have many mitochondria to supply ATP needed transport pumps
Decribe the role of T helper cells
1. Have receptors on their cell-surface membrane which bind to the surface antigens on APCs 2. Produce interleukins- type of cytokine (cell signalling molecule) 3. These interleukins help to stimulate the activity of B cells which increases antibody production, stimulates the production of other types of T cells and attracts and stimulates macrophages to ingest pathogens with antigen-antibody complexes
What experiment can be used to show the movement of auxin across a shoot
1. Have two shoots one intact and one split 2. First experiment- keep shoots in the dark- total auxin produced approximately the same whether shoot is split or not 3. Second experiment- Shoot in unilateral light total auxin produced approximately the same whether shoot split or not ? 4. Third experiment- Shoot in unilateral light but undivided- auxin accumulates on the dark side and lower on the lit side when the soot is intact but when divided the auxin concentration is approximately the same both sides. This suggests that normally auxin is transported across the shoot in unilateral light from the lit side to the dark side
Explain how the structure of veins makes them adapted for their function.
1. Have wider lumen than arteries- help blood move through under low pressure 2. Very little elastic or muscle tissue 3. Contain valves to prevent backflow 4. Blood flow is helped though the veins by contraction of the body muscles surrounding them 5. They take de-oxygenated blood back to the heart under low pressure
Summarise how Darwin and Wallace formulated the theory of evolution by natural selection.
1. He noticed that different islands had different finches- different beaks 2. He realised the design of the beaks was linked to the food available 3. A bird born with a beak more suited to the food would survive longer and have more offspring, passing on its character
List 7 diseases that stem cells have the potential to treat - for each describe how stem cells may be useful.
1. Heart disease- replace damaged muscle tissue after heart attack- normally irreparable 2. Type 1 diabetes- replace insulin producing cells which have been destroyed by the immune system 3. Parkinson's- Replacing the dead dopamine-producing cells in the brain. 4. Alzheimer's- replace brain cells which are destroyed by build up of abnormal proteins. 5. Macular degeneration- causes blindness in elderly and diabetics 6. birth defects 7. Spinal injuries- use stem cell implants in damaged spinal cords
Explain how to calculate heart rate from an ECG.
1. Heart rate (bpm) = 60 / time taken for one heart beat (s) 2. Work out time between one wave and the next
Describe, using a diagram, how hydrolysis of maltose occurs and why water is needed.
1. Hydrolysis of maltose occurs when a water molecule is added to maltose disaccharide 2. the addition of water results in the breakdown of maltose to two alpha- glucose monosaccharides. 3. The 2 hydrogen atoms and the oxygen atom bond with the oxygen joining the monomers. 4. This forms two hydroxyl groups on each monosaccharide (OH)
State the part of the brain involved in thermoregulation and describe its role in this process.
1. Hypothalamus 2. Detects temperature of the blood deep in the body
Describe 5 general ways in which pathogens can damage host tissue, thereby causing harm.
1. Virus- take over cell metabolism 2. Protoctists- take over cells and break them open- don't take over genetic material, just digest and use the cell contents as they reproduce 3. Fungi- digest living cells and destroy them 4. Bacteria- produce toxins that poison or damage the host cells causing disease- some break down cell membrane, some damage or inactivate enzymes and some interfere with genetic material so cell can't divide 5. Fungi- some produce toxins which affect host cells and cause disease
Define VOCs
1. Volatile organic compounds act like pheromones between themselves and other organisms particularly insects 2. They diffuse through the air in and around the plant 3. They are usually only produced when the plant detects attack by an insect pest through chemicals in the saliva of the insect.
Describe the symplast pathway of water movement.
1. Water moves through the symplast- continuous cytoplasm of the living plant cells that is connected through the plasmodesmata- by osmosis. 2. Root hair cell has higher water potential than the next ell along- water diffuses from the soil making the cytoplasm more dilute- so water moves by osmosis to the next cell 3. This continues until the xylem is reached
Describe structure, function and location of the Casparian strip.
1. When water in the apoplast pathway gets to the endodermis cells in the root, it's path is blocked by the casparian strip in the cell walls 2. Now the water is forced to take the symplast pathway 3. This means that water has to go through a plasma membrane- partially permeable so can control whether or not substances in the water get through 4. Once past this barrier the water moves into the xylem
Explain how your body detects that your finger has touched a pin
1. When you touch the pin it exerts mechanical pressure on your skin 2. Pacinian corpuscle found within skin detects pressure 3. pressure changes shape of Pacinian corpuscle 4. stretch-mediated sodium channel in neuronal membrane stretches 5. channel widens 6. sodium ions diffuse into membrane membrane is depolarised/generator potential created 7. generator potential creates an action potential 8. action potential transmitted along neurones to CNS/brain
Name, and state the equipment used to measure, 6 abiotic factors that could be measured when studying the abundance and distribution of organisms in an area.
1. Wind speed- anemometer ms-1 2. light intensity- light meter lx 3. Relative humidity- humidity sensor- mg dm-3 4. pH- pH probe 5. Temperature- temperature probe degrees Celsius 6. Oxygen content in water- dissolved oxygen probe mg dm-3
Describe the steps to carry out an unpaired student's t-test
1. Work out the t-value by using the formula 2. Calculate degrees of freedom df= (n1+n2)-2 3. Then look at corresponding probability values 4. For the data to be considered significantly different from chance alone, the probability must be 5% or less 5. The calculated statistic needs to be less than the t-value at 5% at the degree of freedom to be significant. Otherwise you accept the null hypothesis 6. 95% it is significant 7. 99% highly significant 8. 99.9% very highly significant
State the components of a triglyceride
3 fatty acid tails and a glycerol head
Draw, label and annotate a diagram to show the arrangement of neurones in the "corneal blinking" reflex arc and the actions that occur in the stimulus-response pathway
1. It is a cranial reflex- occurs in the brain not the spinal cord When the cornea of the eye is irritated by a foreign body, the stimulus trigger an impulse along a sensory neurone 2. The impulse then passes through a relay neurone in the lower brain stem. 3. Impulses are then sent along branches of the motor neurone to initiate a motor response to close the eyelids 4. The reflex initiates a consensual response- both eyes are closed in response to the stimulus
State the properties and functions of glycogen
1. It is a polysaccharide of alpha-glucose, with a very similar structure to amylopectin except with a lot more side branches coming off it. 2. loads of branches mean that stored glucose can be released quickly which is important for energy release in animals. 3. it is also a very compact molecule so it's good fro storage.
Describe the structure of xylem and explain how it is adapted for its function.
1. Largely non-living tissue 2. Flow is from roots to shoots and leaves 3. Xylem vessels are long hollow structures made by several columns of tubes fusing together end to end- contain no cytoplasm or end cell wals- improves flow of water 4. Also contain xylem parenchyma and lignin 5. Water and mineral ions move into and out of the vessels through small pits in the walls where there is no lignin
Suggest ways to minimise the spread of communicable disease in animals and in plants.
1. Leave plenty of room between plants 2. Rotate crops 3. Clear fields as thoroughly as possible 4. Handwashing
Describe two problems faced by hydrophytes.
1. Leaves need to float so they are near the surface of the water to get the light needed for photosynthesis 2. Water-logging is a major problem- air spaces of plants need to be full of air, not water
Describe how squamos epithelium tissues are specialised for their function
1. Made of specialised squamous epithelial cells 2. Very thin (contains flat cells) and is one cell thick- allow efficient diffusion 3. Present when rapid diffusion across a surface is essential. 4. Forms lining of lungs and allows rapid diffusion of O2 into blood
Describe the characteristics of Protocista
1. Mainly unicellular 2. A nucleus and other membrane-bound organelles 3. Some have chloroplasts 4. Some are sessile but others move by cilia or flagella or amoeboid mechanisms 5. Nutrients are acquired by photosynthesis (autotrophic feeders), ingestion of other organisms (heterotrophic feeders) or both, some are parasitic
Describe the functions of the transport systems in plants.
1. Metabolic demands- places that don't photosynthesise need glucose and oxygen transported to them and waste products of cell metabolism removed. 2. Metabolic demands-Hormones made in one part of the plant need to be transported to the area where they have an affect. 3. Metabolic demands- mineral ions absorbed by the roots need to be transported to all cells to make proteins to make enzymes and the structure of the cell
Describe 4 ways that the root hairs of root hair cells are adapted as exchange surfaces.
1. Microscopic size- can easily penetrate between soil particles 2. Each microscopic hair has large SA;Vol ratio - thousands on each tip 3. Each hair has a thin surface layer- diffusion and osmosis can take place quickly 4. Concentration of solutes in the cytoplasm of root hair cells maintains a water potential gradient between the soil water and the cell
Suggest two methods used to reduce the likelihood of resistance developing in bacteria.
1. Minimising the use of antibiotics and ensuring every course of antibiotics is completed- reduces risk of resistant individuals surviving and developing into a resistant strain population 2. Good hygiene in hospitals, care home and in general- major impact on spread of all infections
Describe, in principle, how biosensors work.
1. Molecular recognition- The biological molecule produced a signal 2. Transducer- THis signal is converted to an electrical signal by a transducer 3. Display- The electrical signal then produced a visible, qualitative or quantitative signal such as a particular colour on a test strip or reading on a test machine
Define the term homologous chromosomes
1. Pairs of matching chromosomes- each chromosome in the pair contains the same genes but different alleles. 2. One is maternal and one paternal 3. They are usually a similar length and contain centromere in the same position. 4. Pair up in meiosis 1 to form bivalents
State 3 different sources of evidence for evolution
1. Palaeontology- study of fossils and the fossil record 2. Comparative anatomy- the study of similarities and differences between organism's anatomy 3. Comparative biochemistry- similarities and differences between the chemical makeup of organisms
Describe how tannins help protect plants from herbivory
1. Part of a group of compounds called phenols produced by many plants 2. Make up 50% of dry weight of leaves 3. Have very bitter taste which deters herbivores 4. Toxic to insects- bind to digestive enzymes produced in saliva and inactivate them.
Define the term "partial pressure" and compare the partial pressure of oxygen in the blood in capillaries in the lungs with blood in the capillaries of respiring tissues.
1. Partial pressure of oxygen pO2 is a measure of oxygen concentration 2. The greater the concentration of dissolved oxygen in cells, the higher the partial pressure 3. In the alveoli there is a high pO2 in the respiring tissue there is a low pO2
Describe and explain the difference between the functions of RNA polymerase and DNA polymerase
1. RNA polymerase makes RNA and is used in transcription. One strand of DNA used and one strand formed 2. DNA polymerase is used in DNA replication, which is semi-conservative so both strands are used. Before cell division
Draw and label a diagram to show the lac operon and its associated regulatory gene
1. Regulatory gene - lacIgene which makes repressor protein (not part of operon) 2. Promoter - site of RNA polymerase binding 3. Operator - allows the genes to be turned on or off, depending on binding of a repressor protein 4. Structural genes needed to metabolise lactose protein 1 = lac Z protein 2 = lac Y protein 3 = lac A
Comparison of eukaryotic and prokaryotic cells
1. Reproduction: EC- asexual or sexual. PC- Binary fission 2. Cell size: EC- 20-40 um diameter PC- usually 0.5- 5 um diameter 3. location of genetic material: EC- In the nucleus PC- free in the cytoplasm
Describe 3 other factors that affect blood glucose concentration
1. Respiration- some of the glucose in blood is used by cells to release energy. This is required to perform normal body functions 2. Diet- When you eat carbohydrate-rich foods such as pasta and rice etc, the carbohydrates the contain are broken down in the digestive system to release glucose 3. Stress- increases blood-sugar levels
Describe the role of the pancreas as an endocrine gland
1. Responsible for producing insulin and glucagon- essential role in controlling blood glucose concentration 2. Within the exocrine tissue there are small regions of endocrine Islets of Langerhans 3. The cells of the islets of Langerhans are responsible for producing insulin and glucagon, and secreting these hormones directly into the bloodstream
Define nonsense mutation
1. Result in a codon becoming a stop codon instead of coding for an amino acid 2. The result is a shortened protein being synthesised which is normally non-functional
Define misense mutation
1. Result in the incorporation of an incorrect amino acid/acids into the primary structure when the protein is synthesised 2. The mutation could be silent, beneficial or harmful
Describe what happens during the Anaphase 2 stage of meiosis
1. Results in the chromatids of the individual chromosomes being pulled to opposite poles after division of centromeres.
State 3 examples of sinks.
1. Roots that are growing and or actively absorbing mineral ions 2. Meristems that are actively dividing 3. Any part of the plant that are laying down food stores e.g developing seeds, fruits or storage organs
State 2 characteristics which are solely environmentally determined
1. Scars 2. piercings
Draw, label and annotate a graph of quantity of antibody in the blood over time to compare the primary and secondary immune responses.
1. Secondary immune response produces a lot more anitbodies 2. The rate at which antibodies are produced is much faster 3. They are quicker to start producing antibodies
State the "normal" blood glucose concentration
90mg cm-3
Define stimulus
A detectable change in the internal or external environment
Define transducer
A device that converts one type of energy or signal into another. In sensory receptors they convert a stimulus into a nerve impulse called a generator potential
Define insulin
A globular protein hormone involved in the regulation of blood glucose concentration
Define the term "operon"
A group of genes that are under control of the same regulatory mechanism and are expressed at the same time
Define Hox genes
A group of homeobox genes that are only present in animals.
Define light harvesting system/ antennae complex
A group of protein and chlorophyll molecules found in the thylakoid membranes of the chloroplasts in plant cell. The role of the system is to absorb or harvest light energy of different wavelengths and transfer this energy quickly and efficiently to the reaction centre.
Give 3 examples of behavioural adaptations
1. Survival behaviours- opossum plays dead and rabbits freeze when in danger 2. Courtship- many display elaborate behaviour to attract a mate- increases chance of reproducing 3. Seasonal behaviours- migration and hibernation and allows animals to cope with changes in their environment.
Give an example of substrate level phosphorylation and describe what it is.
1. Synthesis of ATP by transfer of phosphate molecule from another molecule. (a phosphorylated intermediate (e.g triose bisphosphate)) 2. The formation of ATP without the involvement of an electron transport chain 3. An example is glycolysis
Define the term "cell mediated immunity" and suggest what it is particularly effective against.
1. T lymphocytes respond to cells of an organism that have been changed in some way e.g. by a virus infection, by antigen processing or by mutation (cancer cell) and to cells from transplanted tissue
Explain how to identify normal heart action, bradycardia, tachycardia, an ectopic heartbeat and atrial fibrillation from an ECG.
1. Tachycardia- waves are closer together 2. Bradycardia- waves are further away from each other 3. Ectopic heartbeat- extra heartbeats out of the normal rhythm- random wave 4. Atrial fibrillation- A lot of mini waves
State 5 factors that affect the rate of an enzyme controlled reaction.
1. Temperature 2. Surface area 3. Concentration of substrate 4. Concentration of enzymes 5. PH
List the factors affecting the rate of diffusion of a molecule.
1. Temperature- higher temp the higher the rate of diffusion- particles have more kinetic energy etc. 2. Concentration difference- greater the difference faster the rate of diffusion because the overall movement from the higher concentration to lower concentration will be larger. 3. Surface area- larger SA higher rate of diffusion 4. Thickness of membrane- thinner the higher the rate of diffusion.
Describe the main stages in a pregnancy test
1. The wick is soaked in the first urine passed in the morning- have highest levels of hCG 2. The test contains monoclonal antibodies that have very small coloured beads attached to them. They will only bind to hCG. If the woman is pregnant the hCG in her urine binds to the mobile monoclonal antibodies and forms a hCG/antibody complex 3. The urine caries on along the test structure until it reaches a window 4. Here there are immobilised monoclonal antibodies arranged in a line or a pattern such as a positive sign that only bind to the hCG/antibody complex.- a coloured pattern appears in the first window 5. The urine continues up through the test to a second window 6. Here there is usually a line of immobilised monoclonal antibodies that bind only to the mobile antibodies, regardless of whether they are bound to hCG or not. This coloured line forms regardless of whether the woman is pregnant- indicated the test is working
How does muscle contraction change the arrangement of the actin and myosin filaments as they appear on an electron micrograph
1. The z lines moving closer together, shortening the sarcomere 2. The H-zone (A band that isn't overlapped with I band) becomes narrower 3. I band/light band gets shorter 4. A band/dark band stays the same 5. The dark part of the dark band remains the same width, as the myosin filaments themselves have not shortened, but now overlap the actin filaments by a greater amount
Draw and label diagrams of a motor neurone
1. They have many short dendrites and a long axon 2. Cell body with nucleus in it on the left side 3. Dendrites attached to the cell body 4. Long axon leading to dendrites on the right side 5. Myelin sheath around the axon with the unmyelinated parts called the nodes of Ranvier
Name and describe the four levels at which genes (or proteins) are regulated
1. Transcriptional- genes can be turned on or off 2. Post-transcriptional- mRNA can be modified which regulates translation and types of proteins produced 3. Translational- translation can be stopped or started 4. Post-translational- proteins can be modified after synthesis which changes their functions
Define saltatory conduction
A form of nerve impulse conduction in which the impulse jumps from one Ranvier's node to the next, rather than traveling the entire length of the nerve fibre
Define the term point quadrat
A frame containing a horizontal bar. At set intervals along the bar, long pins can be pushed through the bar to reach the ground. Each species of plant the pin touches is recorded.
Explain how volume is related to demand and surface area is related to supply. Also explain why supply meeting demand requires adaptations as organisms increase in size.
A high volume means the organism has a lot of cells which all have a metabolic requirement. The larger the SA of the organism the faster the cells can be supplied. Some larger organisms have a very small SA:Vol ratio meaning that they cannot get sufficient nutrients by diffusion alone- must adapt to form more specialised exchange surfaces.
Define homologous structure
A homologous structure is a structure that appears superficially different in different organisms but has the same underlying structure
Define glucagon
A hormone formed in the pancreas which promotes the breakdown of glycogen to glucose in the liver
Names the bond that can link two water molecules together
A hydrogen bond
Describe the structure and function tRNA
1. Transfer RNA - a single polynucleotide strand that's folded into a clover shape. 2. H bonds between specific base pairs hold the molecule in this shape. 3. Every tRNA molecule has a specific sequence of 3 bases at one end called an anticodon. 4. They also have an amino acid binding site at the other end. 5. It is found in the cytoplasm and carries amino acids that are used to make proteins (translation) to the ribosome.
Describe how the xylem vessel is specialised for its function
1. Transports water and minerals around the plant 2. The walls of the cells are strengthened with waterproof lignin- provides structural support 3. Contains hollow xylem vessels which are elongated dead cells. 4. Contains parenchyma cells- fill in gaps between vessels.
Explain the reasons for doing each step in a method to produce a root tip squash to view plant cells in different stages of the cell cycle.
1. Treat the very tips of the roots with HCl 2. Then breaking them open and spreading the cells thinly on a microscope slide using a mounted needle. 3. A few drops of stain are then added to the spread out cells before they are physically squashed beneath a coverslip.
State the 3 categories of lipids (or lipid derived molecules)
1. Triglycerides 2. phospholipids 3. steroids (cholesteral is a type of steroid)
Define the term polymer
A large complex molecule composed of long chains of monomers bonded/ linked together e.g proteins and carbohydrates
Outline the structure and functions of slime capsules in prokaryotic cells
A layer around the cell wall outside the cell that prevents the cell from drying
Define the term "cholesterol",
A lipid containing a hydrocarbon tail attached to a hydrocarbon ring and a hydroxyl group
Define the terms "solvent"
A liquid in which substances or solutes are dissolved forming a solution
Define the Loop of Henle
A long loop of nephron that creates a steep concentration gradient across the medulla
Define the term polymer
A long-chain molecule composed of bonded multiple individual monomers in a repeating pattern
Define the terms "validity"
A measurement is valid id it measures what it is supposed to be measuring. an investigation procedure is valid if it is suitable to answer the question being asked.
Describe what a microscope does and name 4 different types of microscope.
A microscope is an instrument which enables you to magnify an object a lot. -compound light microscope -laser scanning confocal microscope -scanning electron microscope -transmission electron microscope
Define the term disaccharide
A molecule comprising two monosaccharides, joined together by a glycosidic bond
Define the term polynucleotide
A molecule made up of lots of nucleotide joined together in a long chain.
Define the terms "non-competitive inhibitor",
A molecule that binds to an enzyme away from its active site. This changes the shape of the active site so the substrate ca no longer bind.
Define the term monosaccharide
A monomer of carbohydrates, a single sugar
6. Define the term "induced pluripotent stem cell" and explain why they may be very useful in research and medicine.
A multipotent stem cell that has been chemically treated so that it reverts to a pluripotent state.
Define muscle fibre
A muscle cell, especially one of the cylindrical, multinucleate cells that make up skeletal muscles and are composed of numerous myofibrils that contract when stimulated.
Outline how mutations can alter the structure of a protein.
A mutation changes the base sequence of DNA and the base sequence defines the order of amino acids in a protein - the primary structure - this then changes the higher levels of protein structure.
Define silent mutation
A mutation that occurs in the part of a gene that does not code for a protein therefore it will not affect the phenotype
Define insertion
A mutation where one or more extra nucleotides are inserted into a DNA strand
Define substitution
A mutation where one or more nucleotides are substituted for another in a DNA strand
Define the terms "prosthetic group"
A non protein component of a conjugated protein
Define the term cofactor
A non-protein substance which binds to an enzyme and activates it. It can be organic or inorganic.
Define the term organ system
A number of organs working together to carry out a major function in the body.
Describe how triglycerides are used in respiration
1. Triglycerides are hydrolysed to glycerol and fatty acids 2. Glycerol is first converted to pyruvate before undergoing oxidative decarboxylation producing an acetyl group which is picked up by coenzyme A forming Acetyl CoA 3. The fatty acids in a triglyceride molecule can be converted to acetyl groups which combine with coenzyme A to form acetyl CoA by beta oxidation without being converted to pyruvate first. This can lead to the formation of as many as 50 acetyl CoA molecules resulting in the synthesis of up to 500 ATP 4. Produce more energy than alcohol and carbs
Describe 5 functions of water in plants.
1. Turgor pressure- provides a hydrostatic skeleton to support the stems and leaves 2. Turgor- also drives cell expansion- force that enables plant roots to force their way though tarmac and concrete 3. Loss of water through evaporation keeps the plant cool 4. Mineral ions and the products of photosynthesis are transported as aqueous solutions 5. Water is the raw material for photosynthesis
State the location of the adrenal glands in the body and describe their structure
1. Two small glands that are located on top of each kidney and are made up of two distinct parts surrounded by a capsule 2. The adrenal cortex- the outer region of the glands, produces hormones vital to life e.g. cortisol and aldosterone 3. The adrenal medulla- the inner region of the glands. This produces non-essential hormones, such as adrenaline which helps the body react to stress.
How is type 1 diabetes treated
1. Type 1 diabetes is controlled by regular injections of insulin and is therefore said to be insulin dependent 2. People regularly test their blood glucose concentration 3. Based on the concentration the person can work out the dose of insulin they need to inject 4. The insulin administered increases the amount of glucose absorbed by cells and causes glycogenesis to occur resulting in a reduction of blood glucose concentration 5. Too little or too much results in hyper/hypoglycaemia
Explain how capillaries are adapted for their function.
1. Very thin walls- so have efficient diffusion of substances- endothelium is one cell thick 2. They are small enough to form the immense networks needed to exchange substances between the blood and tissues 3. Provide large surface area for diffusion 4. Relatively slow movement of blood through the capillaries allows time for the exchange of materials by diffusion
Define the term meiosis
A type of cell division where the nucleus divides twice resulting in halving the number of chromosomes to create four genetically different haploid cells.
Define the term "mitosis"
A type of cell divisions where parent cell divides to produce two genetically identical daughter cells. It takes place in the mitotic phase of the cell cycle.
Define peritoneal dialysis
A type of dialysis that uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood
Define the term selectively neutral allele
A variety of a gene that doesn't provide a selective advantage or disadvantage to the organism
Describe structure of a water molecule
A water molecule is composed of 2 hydrogen atoms and 1 oxygen atom. they are bonded by polar covalent bonds.
Define blood plasma
A yellow liquid that makes up 55% of blood volume. It carries a lot of stuff
Identify which transport mechanisms require an input of energy from ATP.
Active transport Endocytosis Exocytosis
Define the terms "active transport"
Active transport is the movement of particles across the plasma membrane against a concentration gradient. Requires energy
Define the term adaptation and state 3 types of sdaptaion
Adaptations are characteristics that increase an organism's chance of survival and reproduction in the environment 1. Anatomical- physical features 2. Behavioural- the ways an organism acts- inherited or learnt form parents 3. Physiological- processes that take place inside an organism
Define the term "phospholipid bilayer".
An arrangement of phospholipids found in cell membranes, the hydrophillic phosphate heads form both the the inner and outer surface of a membrane, sandwiching the fatty acid tails to form a hydrophobic core.
Determine the term artifacr with reference to microscopy
An artefact is a visible object or distorted cell structure present in an electron micrograph (or other micrograph) due to the sample preparation process
Define the term polysaccharide
A polymer made up of many sugar monomers (monosaccharides)
Define the term oligomer
A polymer molecule consisting of a small number of monomers
Define the term sieve plates
Areas between the cells of the phloem where the walls become perforated giving many gaps and a sieve-like appearance that allows the phloem contents to flow through.
List, in order, the sequence of blood vessel types that blood passes through once it leaves the heart.
Arteries, arterioles, capillaries, venules, veins
Define endotherm
Animals that rely on their metabolic processes to warm their bodies and maintain their core temperature
Define voltage gated channel
Any ion channel that opens and closes in response to changes in electrical potential across the cell membrane in which the channel is situated
Define transverse tubule (T-tubule)
Any of the small tubules which run transversely through a muscle fibre and through which electrical impulses are transmitted.
State the role of glycoproteins in the membrane.
Are intrinsic proteins. 1. Play a role in cell adhesion to hold cells together 2. Act as receptors for chemicals and hormones when chemicals bind ti the receptor it elicits a response from the cell. this may cause a direct response or set off a cascade of events inside the cell- cell communication or signalling 3. Act as antigens for cell recognition for non-self 4. Stabilises membrane structure by forming hydrogen bonds with water molecules
Describe how CO2 concentration affects the rate of photosynthesis
Carbon dioxide is needed as a source of carbon, so if all other conditions are met, increasing the carbon dioxide concentration increases the rate of carbon fixation in the Calvin cycle and therefore the rate of TP production.
tate the elements present in carbohydrates.
Carbon, Hydrogen, oxygen
Carbohydrates- elements that make up the molecules
Carbon, hydrogen and oxygen
Lipids- elements that make up the molecules
Carbon, hydrogen and oxygen, (phosphorus in phospholipids)
Proteins- elements that make up molecules
Carbon, hydrogen. oxygen, nitrogen
Name, and state the location of, the enzyme that catalyses the production of carbonic acid.
Carbonic anhydrase in the cytoplasm of the red blood cell.
How can you work out cardiac output
Cardiac output = stroke volume * heart rate
State 1 particular example of a carrier proteins
Carrier Protein- GLUT1 is found in almost all animal cells and specifically helps to transport glucose across the plasma membrane
Define the term catabolic reactions
Catabolism refers to chemical reactions that result in the breakdown of more complex organic molecules into simpler substances. Catabolic reactions usually release energy that is used to drive chemical reactions i.e. anabolic reactions.
State the substrates and products for the enzymes catalase
Catalyses the breakdown of hydrogen peroxide to oxygen and water. Hydrogen peroxide is a toxic by-product of several cellular reactions- can kill cells if builds up.
State the substrates and products for the enzymes trypsin.
Catalyses the hydrolysis of peptide bonds turning big polypeptides into smaller ones. Produced in the pancreas and secreted into the small intestine.
State the substrates and products for the enzymes amylase
Catalyses the hydrolysis of starch into maltose in the mouth. Maltose is broken down to glucose by maltase which is in the small intestine. It is found in saliva and secreted into the mouth by the salivary glands.
Define the term "crenation"
Cells shrink by osmosis as water leaves the cells- animal cells
Define the term guard cell
Cells that can open and close the stomatal pores controlling gaseous exchange and water loss in plants
Define the term eukaryotic cell
Cells with a nucleus and other membrane bound organelles
Define the term metabolism
Cellular metabolism is all the biochemical reactions taking place withing a cell, including all the reactions involved in digesting food molecules.
Explain the role of the centrioles and spindle fibres in mitosis.
Centrioles form spindle fibres in prophase. Spindle fibres move the chromosomes to form a plane in the centre of the cell and then pull the chromatids apart
Outline the role of checkpoints to control the cell cycle.
Checkpoints are the control mechanisms of the cell cycle. They monitor and verify whether the processes at each phase of the cell cycle have been accurately completed before the cell is allowed to progress to the next phase.
Define neurotransmitter
Chemical involved in communication across a synapse between adjacent neurones and a muscle cell
Define hormone
Chemical messengers which travel around the body in the bloodstream
Name the photosynthetic pigment in the reaction centre of a photosystem.
Chlorophyll a
Explain how enzyme cofactors could play a role in gene regulation
Cofactors bind to proteins that regulate transcription changes binding of proteins to control elements rate of transcription changed RNA polymerase activated
Explain how the polar nature of water makes it cohesive
Cohesion is the attraction between molecules of the same type. Water molecules are very cohesive because they have hydrogen bonds between them as they are polar
Define the term cohesion
Cohesion refers to the sticking together of alike molecules, such as water molecule being attracted to another water molecule.
State the roles of DNA polymerase in DNA replication.
DNA polymerase joins the nucleotides on the new strand together.
Name the taxonomic level that has been added above kingdom.
Domain
Define the term enzymes
Enzymes are biological catalysts that interact with substrate molecules to facilitate chemical reactions. Usually globular proteins.
Explain how enzymes can affect both the structure and function of cells and whole organisms.
Enzymes can affect the structures in an organism e.g. enzymes are involves in the production of collagen and other proteins. These can affect the structures of cells and organisms. Enzymes are specific so carry out a specific function, so can change the function of cells.
Define the term extracellular enzymes
Enzymes outside cells Amylase and trypsin
Explain how the polar nature of water makes it a good solvent for ionic and polar molecules
As one side of the water molecule is delta +ve and one side is delta -ve they attract to ionic compounds and polar. because the delta +ve side attracts to the negative ion in the compound (Cl-) and levers it out of its solid lattice structure and the many H2Os surround it (sphere of hydration) meaning its' dissolved. the same happens with the delta -ve side and the +ve ion
Explain why wavelength of light cannot be a limiting factor for photosynthesis whereas light intensity, temperature and carbon dioxide concentration can be.
Because chloroplasts contain many different photosynthetic pigments e.g chlorophyll a/b, xanthophylls and carotenoids
Explain why it is useful for photosynthetic organisms to have many different photosynthetic pigments.
Because different pigments can absorb different wavelengths of light. This allows them to adjust to different intensities in light- orange leaves in water In autumn plants stop producing chlorophyll.
Explain why it may be possible to test for drug use some time after a person has taken the drug
Because drugs or metabolites (which are the breakdown products of drugs) are filtered through the kidney and stored in the bladder
Explain why an enzyme only catalyses one type of reaction.
Because for an enzyme to work the substrate has to fit into the active site- its shape has to be complementary. If the shape doesn't match the active site the reaction won't be catalysed.
Describe how a spirometer measures change in lung volume and explain why it cannot measure total lung volume.
Because it can't measure residual volume- what is already in your lungs- only what is breathed in and out. Total lung volume measures residual volume and vital capacity
Explain why a neurone is active when it is said to be resting
Because it is still actively transporting ions using the sodium potassium pump
Describe how root hair cells are specialised for their funciton
Function- Absorb mineral ions and water from the soil Structure: 1. Have lots of root hairs (long extensions)- increase SA of cell, to maximise uptake of water and minerals 2. Thin permeable cell wall- for entry of water and ions 3. Cytoplasm contain extra mitochondria to provide the energy needed for active transport.
Describe how sperm cells are specialised for their function
Function- deliver genetic information to the female gamete Structure: 1. Have a flagellum- capable of movement 2. They have lots mitochondria- to provide energy to swim 3. Acrosome on the head contains digestive enzymes- released to digest the protective layers around the ovum, allowing the sperm to penetrate.
Describe how palisade cells are specialised for their function
Function- to do most of the Photosynthesis Structure: 1. Contain many chloroplasts- absorb large amounts of energy for photosynthesis 2. The cells are a rectangular box shape- can be closely packed to form a continuous layer. 3. Have thin cell walls- increase the rate of diffusion of CO2
Describe how neutrophils are specialised for their funciton
Functions- Defend the body from disease Structure: 1. They have a flexible shape- allows them to engulf foreign particles or pathogens. 2. Multi-lobed nucleus- easier to squeeze through small gaps to get to site of infections. 3. Cytoplasm contain many lysosomes- they contain digestive enzymes to break down the engulfed particles
List the 3 stages of interphase in order
G1- first growth phase S- synthesis phase G2- Second growth phase
Define nodes of Ranvier
Gaps between each adjacent Schwann cell. With the myelin sheath they allow faster speed of transmission (2-3 micrometres and in humans occur every 1-3mm)
Define systemic circulation
Flow of blood away from the heart to the brain,liver, kidney, stomach and other organs, the limbs, and the muscles of the body, and then the return of this blood to the heart.
Define the term tracheal fluid
Fluid found at the ends of the tracheoles in insects that helps control the surface area available for gas exchange and water loss.
Describe three ways in which inactive precursor may be activated.
For a precursor to be active it needs to undergo a change in tertiary structure by: the addition of a co-factor The action of another enzyme (protease) changing conditions (temp or pH level)
State the names of the anatomical layers in arteries and veins
From outer to inner 1. Tunica externa (collagen which provides structural support to maintain the shape and volume of the vessel) 2. Tunica media (smooth muscle layer which contracts or relaxes changing the size of the lumen and a elastic layer which contain elastic fibres which allow it to stretch and recoil providing the vessel walls with flexibility. 3. Tunica interma (single layer of cells called the endothelium comes into direct contact with the blood so is very smooth to allow blood to move without resistance)
Where are erythrocytes and neutrophils are produced from
From stem cells in bone marrow which undergo differentiation
State the products of the Krebs cycle
From two simultaneous cycles (divide by 2 for products of one) 1. ATP x2 - Energy 2. Reduced FAD x2 (FADH2) -coenzyme that delivers electrons to transport chain 3. Reduced NAD x6 -coenzyme that delivers electrons to transport chain 4. CO2 x4- by product 5. Oxaloacetate x2- Re-used in Krebs cycle to combine with acetyl group
Give two examples of what sucrose can be converted into, and what purpose each serves
Glucose for respiration Starch for storage
Carbohydrates- examples of functions
Glucose- energy source for R Starch - energy store in plants Glycogen- energy store in animals Cellulose- structure and support of cell wall in plants
Explain how an adjustment to the "plane of focus" can alter what is viewed within a cell.
If you change the focus while looking through a microscope you will notice different parts of the image will come into focus and other parts will go out of focus. The plane of focus is the horizontal plane where what you are looking at is in focus. It is usually not very thick so it is hard to focus on things that are not flat. When you focus the microscope you move the plane of focus up and down, which is why different parts of what you are looking at come in and out of focus.
What regulates both mitosis and apoptosis?
Hox genes
Define the term reflex action
Involuntary response to a sensory stimulus
Define the term "anomaly"
Is a value in a set of results that is judged not to be part of the inherent variation
Describe the significance of G0 as a phase that cells enter when they leave the cell cycle
It is the place where a cell leaves the cycle, reasons could be: 1. Differentiation 2. DNA of a cell may be damaged so it is no longer viable 3. As you age- the number of these cells in your body increases- linked to arthritis and cancer
Describe the significance of G0 as a phase that cells enter when they leave the cell cycle.
It is the place where a cell leaves the cycle, reasons could be: 1. Differentiation 2. DNA of a cell may be damaged so it is no longer viable 3. As you age- the number of these cells in your body increases- linked to arthritis and cancer
State what the presence of an enzyme does to the activation energy for the reaction and explain why this increases the rate of reaction.
It lowers the activation energy: If two substrate molecules need to be joined attaching to the enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily. if the enzyme is catalysing a breakdown reactions fitting into the active site puts a strain on bonds in the substrate. This strain means the substrate molecules break up more easily.
Explain the importance of DNA replication conserving genetic information with accuracy.
It makes sure genetic information is conserved each time the DNA in a cell is replicated.
Explain how the polar nature of water gives a high latent heat of vapourisation
It takes a lot of energy to break the hydrogen bonds (polar) between water molecules because hydrogen bonds absorb a lot of energy, so a lot of energy is used up when trying to evaporate it
Explain how to calculate the number of glycosidic bonds in a carbohydrate given the number of monosaccharides it is made up from.
It will be one less c-c-c-c-c-c 6 monosaccharides but only 5 bonds
Define the term evolution
The change in allele frequency within a gene pool over time
Define action potential
The change in the potential difference across the neurone membrane of the axon when stimulated (approx +40mV)
Give two examples of coenzymes that are synthesised from vitamins in our diet.
The coenzyme NAD is derived from vitamin B3. NADP is also derived from vitamin B3.
Define phylogeny
The evolutionary relationships between organisms
Define the term crossing over
The exchange of part of a chromosome between chromatids of homologous pairs- occurs at chiasmata
Define the term random independant assortment
The fact that which daughter cell a chromosome ends up in after meiosis 1 or a chromatid after meiosis 2 is random and independent of the fate of chromosomes from other homologous pairs.
Define heamodialysis
The filtering of blood through a semi-permeable membrane in the dialysis machine to remove waste products
Define triplet code
The genetic code is a sequence of three nucleic acid bases called a codon. Each codon codes for one amino acid.
Define degenerate
The genetic code is degenerate because there are many instances in which different codons code for the same amino acid.
Define the term centromere
The region at which two chromatids are held together
Draw a graph showing how temperature affects the initial rate of an enzyme-controlled reaction.
The graph goes up then down. The peak is the optimum temperature. Not symmetrical slower incline than decline.
Draw a graph showing how substrate concentration affects the initial rate of an enzyme-controlled reaction.
The graph increases in a straight line and then curves and plateaus.
Define synapse
The junction (small gap) between two neurones, or a neurone and an effector
Define morphogenesis
The regulation of the pattern of anatomical development
Define selective reabsorption
The reabsorption of selected substances needed by the body in the kidney tubules
Define the term allele frequency
The relative frequency of a particular allele in a population in a given time
Define secondary immune response
The relatively fast production of very large quantities of the correct antibodies the second time a pathogen is encountered as a result of the immunological memory.
Define the term primary immune response
The relatively slow production of a small number of the correct antibodies the first time a pathogen is encountered
Describe the function of glucocorticoids
The release of these hormones from the adrenal cortex is controlled by the hypothalamus 1. Include cortisol which helps regulate metabolism by controlling how the body converts fats, proteins, and carbs to energy 2. It also helps regulate blood pressure and cardiovascular function in response to stress 3. Another glucocorticoid hormone released is corticosterone. This works with cortisol to regulate the immune response and suppress inflammatory reactions
Define dehydrogenation
The removal of a hydrogen atom
Define deamination
The removal of the nitrogen group during the breakdown of amino acids
Define the term product
The result of a chemical reaction.
Explain what a hydrogen bond is, which types of atoms it can join together and where they occur in biology
The slightly negatively-charged oxygen atoms attract the slightly negatively-charged hydrogen atoms of other water molecules - this attraction is hydrogen bonding. Hydrogen bonding occurs between a hydrogen atom and another strongly electro-negative atom of a polar covalent bond in the same or another molecule
Explain how a competitive inhibitor affects the rate of an enzyme-controlled reaction.
Thye have a similar shape to that of substrate molecules. They compete with the substrate molecules to bind to the active site, but no reaction takes place. Instead they block the active site, so no substrate molecules can fit in. If there is a high concentration of the inhibitor then it'll take up nearly all the active sites. Slows the rate of reaction
Draw a table comparing active and passive immunity.
Time taken- A: not immediate, P: immediate Duration- A: long term, P: short term Exposure to antigens- A: Yes P: No Clonal expansion/selection- A: Yes, P:No Antibodies supplied/ made- A: made, P: supplied Production of memory cells- A: yes, P: no Requires fully functioning immune system- A: Yes, P: no
Define tip
Tips on phylogenetic trees represent groups of descendant organisms
Define meristems
Tissue found at regions of growth in plants. Contains stem cells.
Define the term purkyne fibres
Tissue that conducts the wave of excitation to the apex of the heart
Describe the function of the elastic fibres in the alveoli walls
To recoil/ expel air/ prevent bursting
Define euchromatin
Loosely packed DNA present during interphase
Interpret a graph of ventricular pressure
Low at first but gradually increases as the ventricles fill with blood as the atria contract/The pressure rises dramatically when the AV valve close as the ventricle contracts/As the pressure goes above the aortic pressure blood is forced into the aorta and the semi lunar valves open/Pressure falls as the ventricles empty and walls relax/Semi-lunar valves shut when the pressure of the ventricle becomes lower than the aorta
State the effects insulin has on cells
Lowers blood glucose concentration by: 1. Increasing the rate of absorption of glucose by cells, in particular skeletal muscle cells 2. Increasing the respiratory rate of cells- this increases their need for glucose and causes a higher uptake of glucose from the blood 3. Increasing the rate of glycogenesis- insulin stimulates the liver to remove glucose from the blood by turning the glucose into glycogen and storing it in the liver and muscle cells 4. Increasing the rate of glucose to fat conversion 5. Inhibiting the release of glucagon from the α-cells of the islets of Langerhans
What is a lysosome and why is the membrane that surrounds it important?
Lysosomes are specialised vesicles that contain hydrolytic enzymes for breaking down waste material. The membrane that forms lysosomes has an important role in compartmentalising these enzymes away from cell structures that could be damaged by activity of the enzyme
Another example of gene regulation in prokaryotes is the trp operon. this operon codes for the production of tryptophan, an essential amino acid for e coli. when tryptophan is available in the environment the structural genes in the trp operon are not expressed Suggest a mechanism for the genetic regulation of this operon
Tryptophan binds to repressor protein shape of repressor protein changes repressor protein binds to promoter blocks RNA polymerase from binding transcription prevented of genes coding for enzymes responsible for tryptophan synthesis
Outline the link between cell-cycle regulation and cancer.
Tumours are often the result of damage or spontaneous mutation of the genes that encode the proteins that are involved in regulating the cell cycle, including the checkpoint proteins.
Define the term lymphocyte
WBC that make up the specific immune response
Draw a table to compare the effects of external solutions, with different water potentials in comparison to the water potential in a plant cell.
Water Potential of external solution compared to cell solution: Higher (hypotonic) - water enters the cell- turgid Equal (isotonic)- no net movement of water- no change Lower (hypertonic) - water leaves the cell- shrinks (flaccid)- plasmolysed
Explain why water is a polar molecule
Water is composed of hydrogen and oxygen atoms and bonds between oxygen and hydrogen involve unequal sharing of electrons in bonds resulting in the oxygen atom being more negative and the hydrogen atoms being more positive
Explain how the polar nature of water means that is has a lower density when solid
Water molecules are held further apart in ice than in liquid water because each water molecule form four hydrogen bonds to other water molecules, making a lattice shape. So takes up a greater volume in less space- so ice is less dense than liquid water
Define the term photolysis
Water molecules are split into hydrogen ions, electrons and oxygen molecules using energy from the Sun. H2O →2H+ + 2e- + 1/2 O2
Explain the biological significance of low viscosity
Water molecules slide past each other readily so flows readily. allows transport through vessels e.g. xylem and blood vessels
Describe the role of the adrenal cortex and the hormones produced by it
Production of hormones by adrenal cortex is controlled by hormones released from the pituitary gland in the brain. 3 main types of hormones: 1. Glucocorticoids 2. Mineralocorticoids 3.Androgens
State the products of digestion of a triglyceride (include partial digestion) and state what would happen to the pH of the solution (and why).
Products of digestion- free fatty acids and monoglycerides the PH of the solution would go down- more acidic- because you have free fatty acids which are acids in the solution
Define apoptosis
Programmed and controlled cell death important in controlling the body form and in the removal of damaged or diseased cells
Define dendrite
Projections of a neurone that receives signals from other neurones they conduct electrical neurones to the cell body for the cell to function
List examples of both prokaryotic and eukaryotic cells.
Prokaryotic 1. bacteria Eukaryotic 1. Plants 2. Animals 3. fungi 4. Protoctists
Suggest why the lack of membrane-bound organelles does not stop prokaryotic cells making proteins
Prokaryotic cells have ribosomes, which are needed for protein synthesis. Ribosomes are not membrane bound
Night time
Rate of respiration > rate of photosynthesis
Define a catabolic reaction
Reactions of metabolism that breaks molecules down into smaller units- these reactions release energy
Define neurotransmitter receptors
Receptor molecules which the neurotransmitter binds to in the postsynaptic membrane
Define the term "herbaceous"
Refers to a plant that has a non-woody stem and which dies back at the end of the growing season.
Define the term sink
Regions of a plant that require assimilates to supply their metabolic needs e.g. roots, fruits
Define intron
Regions of non-coding DNA or RNA
SA and Vol of cuboid
SA: 2(bh + bl + hl) Vol: hbl
SA and Vol of cylinder
SA: 2πr(r + l) Vol: πr^2l
Define the term "sampling" and explain why it is important.
Sampling means taking measurements of a limited number of individual organisms present in a particular area. 1. Can be used to estimate the number of organisms in an area without having to count them all- abundance 2. Can be used to measure particular characteristic of an organism- measuring height of plants and taking an avaerage
Define the term interrupted belt transect
Sampling using a frame quadrat at specific intervals along a line transect.
Define random smapling
Sampling where each individual in the population has an equal likelihood of selection.
Define the term "sister chromatids"
Sister chromatids are the two identical copies formed by the replication of a single chromosome, with both copies joined together by a centromere.
Define the term spiracle
Small openings along the thorax and abdomen of an insect that open and close to control the amount of air moving in and out of the gas exchange system.
Define sensory receptor
Specialised cell that detects a stimulus
Define Islet of Langerhans
Specialised cells within the pancreas responsible for producing insulin and glucagon
Define divergent evolution
Species diverge over time into two different species, resulting on a new species becoming less like the original one
Define the term "keystone species" and explain why they are important in maintaining biodiversity.
Species which are essential for maintaining biodiversity- they have a disproportionately large effect on their environment relative to their abundance. e.g. Sea stars eat mussels and sea urchins, which have no other natural predators. If the sea star was removed from the ecosystem, the mussel undergoes a population explosion, reducing the number of other species in the area as they compete for space and other resources.
consider the validity of this statement "all hox genes are homeobox genes but not all homeobox genes are hox genes"
Statement is valid Hox genes are one form of homeobox gene present in vertebrates in Hox clusters other forms of homeobox gene present in other clusters
Explain why statistical tests are important and what they are used for
Statistical tests can be used by scientists to determine the significance of data collected
Define the term atrio-ventricular node (AVN)
Stimulates the ventricles to contract after imposing a slight delay to ensure atrial contraction is complete
What does the mecahnoreceptor do
Stimulus- pressure and movement Example- Pacinian corpuscle (detects pressure Example of organ- skin
Outline the structure and functions of the golgi apparatus
Structure 1. A group of fluid-filled, membrane bound, flattened sacs 2. Vesicles are often seen at the edges of the sacs Function 1. It processes and packages new lipids and proteins into vesicles 2. It also makes lysosomes 3. It modifies proteins
Outline the structure and functions of the cell wall
Structure 1. A rigid structure that surrounds plant cells 2. It's made mainly of carbohydrate cellulose Function 1. Supports plant cells
Outline the structure and functions of lysosomes
Structure 1. A round organelle surrounded by a membrane with no clear internal structure Function 1. Contains digestive enzymes which are kept separate from the cytoplasm by the surrounding membranes. they can be used to digest invading cells or to break down worn out components of the cell.
Outline the structure and functions of the rough endoplasmic reticulum
Structure 1. A system of membranes enclosing flattened sacs called cisternae 2. the surface is covered with ribosomes Functions 1. Folds and processes proteins that have been made at the ribosomes
Outline the structure and functions of the flagella
Structure 1. Flagella are like cilia but longer 2. they stick out from the cell surface and are surrounded by the plasma membrane 3. Inside they have two microtubule in the centre and 9 pairs around the edge Functions 1. Microtubules contract to make the flagellum move 2. they are like outboard motors to propel cells forward
Outline the structure and functions of flagellum in prokaryotic cells
Structure 1. Made of protein flagellin arranged in a helix 2. thinner 3. Not got a 9+2 arrangement
Outline the structure and functions of the smooth endoplasmic reticulum
Structure 1. Similar to RER but with no ribosomes Function 1. Synthesises and processes and stores lipids and carbs
Outline the structure and functions of the chloroplasts
Structure 1. Small, flattened structure found in plant cells 2. surrounded by a double membrane 3. also has membranes inside called the thylakoid membranes 4. these membranes are stacked up in some parts of the chloroplast to form grana 5. Grana are linked together by lamellae- thin, flat pieces of thylakoid membrane Function 1. Site of Photosynthesis 2. Some parts of photosynthesis happen in the grana 3. Other parts happen in the stoma (a thick fluid found in chloroplasts)
Outline the structure and functions of the plasma membrane
Structure 1. The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells 2. It's made mainly of proteins and lipids Functions 1. Regulates the movement of substances into and out of the cell 2. it also has receptor molecules on it, which allow it to respond to chemicals like hormones
Outline the structure and functions of mitochondrian
Structure 1. Usually oval shaped 2. has a double membrane - the inner one is folded to form structures called cristae 3. inside is a matrix, which contains enzymes involved in Respiration Function 1. Site of aerobic Respiration where ATP is produced 2. Found in very large numbers in cells that are v active and require a lot of energy.
Outline the structure and functions of ribosomes
Structure 1. Very small organelle that either floats free in the cytoplasm or is attached to the RER 2. It is made up of proteins and RNA 3. Not surrounded by a membrane Function 1. the site where proteins are made
Outline the structure and functions of cell wall in prokaryotic cells
Structure 1. made out of peptidoglycan or murein Function 2. structure and support for a cell
Outline the structure and functions of plasmid in prokaryotic cells
Structure 1. small loop of DNA Function 1. used to swap genetic material with other bacteria so they can evolve very quickly
Outline the structure and functions of the cilia
Structure 1. small, hair like structures found on the surface membrane of some animal cells 2. in the cross-section they have an outer membrane and a ring of nine pairs of protein microtubules inside, with a single pair of microtubules in the middle Functions 1. the microtubules allow the cilia to move. this movement is used by the cell to move substances along the cell surface
Define the term analogous structure
Structures that have adapted to form the same function but have a different genetic origin
Suggest some reasons why some organisms need specialised exchange surfaces.
When they have a small SA:Vol ratio diffusion is too slow so they need to have specialised exchange system to keep up with metabolic demands
Describe how tidal volume and breathing rate link to oxygen uptake and explain the importance of the change in tidal volume and breathing rate during exercise.
When you are exercising you need more oxygen for respiration to provide energy. The larger the the tidal volume and breathing rate the larger the volume of oxygen uptake- so you need them to be larger when exercising.
Explain why there is a need to be able to alter heart rate in humans
When you exercise or in times of danger, it is essential that the heart rate increases to provide that extra oxygen required for increased respiration
Describe what happens during ventricular systole
The atria relax /The ventricles contract- decreasing their volume which increases their pressure/The pressure becomes higher in the ventricles than the atria which forces the AV valves shut to prevent backflow to the atria/The pressure in the ventricles is also higher than in the aorta and pulmonary artery, which forces open the SL valves and blood is forced into the arteries.
State 3 similarities and 3 differences between a typical plant and animal cell.
Similarities 1. both have nucleus 2. both have plasma membrane 3. both have cytoplasm differences 1. plants also have chloroplasts 2. plants have a cell wall 3. Plants have a large permanent vacuole
Draw a table listing the properties and differences between alpha-glucose and ribose.
Similarities: 1. They are both carbohydrates 2. Both monosaccharides 3. Both have the same general formula 4. Both very soluble in water Differences: 1. Glucose has 6 carbons whereas ribose has 5 carbons 2. Glucose is a hexagon and ribose is a pentagon 3. Glucose main function- production of ATP during aerobic R . 4. Ribose main function- Forms a component of nucleotide DNA and RNA. and also a component of ATP
describe one similarity and one difference between temporal and spatial summation
Similarity - both result in a build-up of neurotransmitter in the synapse / both result in an action potential being triggered difference - spatial is a result of neurotransmitter being released from many neurones into the same synapse, temporal is a result of small amounts of neurotransmitter being released from a neurone several times in a short period
Describe the function of the valves and tendinous cords (valve cords/tendons) in the heart.
The atrioventricular valves link the atria to the ventricles and the semi-lunar valves line the ventricles to the pulmonary artery and aorta /The valves only open one way /If there is a higher pressure behind a valve it is forced to open, if the force is higher in front, it is forced to shut /Means the flow of blood is unidirectional and prevent backflow /The tendinous cords make sure the valves are not turned inside out by the pressure exerted when the ventricle contracts
Define the term osmoregulation
The balancing and control of the water potential of the blood
Define body plan
The basic shape of members of an animal phylum; the general structure each individual organism assumes as it develops
What is diffraction?
The bending of light as it passes close to the edge of an object
Define the term opperculum
The bony flap covering the gills of bony fish. Part of the mechanism that maintains a constant flow of water over the gas exchange surfaces.
Define the terms "endocytosis"
The bulk movement of materials into cells via invagination of the cell-surface membrane forming a vesicle. The process by which a cell surrounds substances with a section of its plasma membrane and takes them into the cell.
Define the terms "exocytosis"
The bulk transport of materials out of cells. Vesicles containing the material fuse with the cell-surface membrane and the contents are released to the out side of the cell.
Define the term "cytolysis"
The bursting of an animal cell caused by increasing hydrostatic pressure as water enters by osmosis
Define the term spore
The cells that some organisms use to reproduce asexually, including some protoctists and fungi
why does staining with heavy metals take place?
creates contrast in electron beams
What is thalidomide used for now?
currently used in the treatment of some forms of cancer. stops development of some tumours. belived that it prevents the formation of networks of capillaries which are necessary for some tumours to grow and develop.
most of our knowledge of development comes from the study of...
drosophila melangaster (fruit fly)
Define the term "anabolic steroid" and explain why they may give a benefit to athletes
drugs that mimic the action of the male sex hormone testosterone and they stimulate the growth of muscles
Discuss polar nature of water and its importance
due to being a polar molecule water acts as a solvent in which many of the solutes in an organism can be dissolved. the cytosol of prokaryotes and eukaryotes is mainly water. many solutes are also polar molecules (amino acids, proteins and nucleic acids) water acts as a MEDIUM for chemical reacts and helps transport dissolved compounds into and out of cells
Why is Drosophila a good organism to study?
easy to breed and keep cheap reproduces rapidly/ short life cycle 4 chromosomes and genome known rapidly produces mutations so many known ones that can be studied
Define the term "monoclonal antibody"
antibodies from a single clone of cells that are produced to target particular cells or chemicals in the body
Types of organisms prepared from viewing by a wet mount are...
aquatic organisms and other living organisms
Explain how the variety of amino acids leads to a wide range of dipeptides and very quickly to an incredible variety of polypeptide chains.
because the R-group in amino acids is variable so when they are sequenced together in a condensation reaction the resulting polypeptide chain is very different.
Explain how the polar nature of water makes it's freezing point 0 and boiling point 100
because water is polar hydrogen bonds form between the molecules collectively these bonds require a lot energy to break and seperate the water molecules- which is why water has a high boiling point
Explain the biological significance of water's boiling and freezing point
because water's boiling point 100 degrees it is liquid at most environmental temperatures and provides a stable aquatic environment for animals and a medium for chemical reactions
How is the hepatic artery and portal vein connected to the central vein?
by capillaries called sinusoids
How can a 3d image be produced by a Laser scanning confocal microscope?
by creating images at different focal planes
each lobule has a ...
central vein that connects to the hepatic vein
The lac operon is often referred to as being "leaky" meaning that it is still transcribed to a limited extent even in the absence of lactose a) using your knowledge of how the lac operon works, explain why this is necessary
enzyme coded for by lac operon enables lactose to enter bacteria lactose binds to repressor protein (repressor) protein changes shape transcription no longer blocked enzymes needed to metabolise lactose are synthesised
what lines of evidence support the idea that how gene complexity has been instrumental in evolution and speciation of animals with different body patterns?
found in all animals known to control body development general trend that simpler animals have fewer hot genes and clusters comparison of hox gene evolution and animal evolution bear striking parallels increases in number of hox genes may have led to greater complexity in body structure
electron microscopes produce images with much...
greater resolution than light microscopes and so more detail can be seen
RER
has ribosomes bound to the surface and is resposible for the synthesis and transport of proteins
How does a COMPOUND light microscope work?
it has 2 lenses, the objective lenbs is placed near to the specimen and an eyepiece lens through which the specimen is viewed. the objective lens produces a magnified image, which is magnified again by the eyepiece lens. this objective/eyepiece lens configuration allows for much highter magnification and reduced chromatic aberration than that in a simple light microscope
Outline the structure and functions of the plasma membrane in prokaryotic cells
it has one but not around organelles
what is the acid-fast technique
it is used to differentiate species of mycobacterium from other bacteria. a lipid solvent is used to carry carbolfuchsin dye into the cells being studied. the cells are then washed with a dilute acid-alcohol solution. mycobacterium are not affected by the acid-alcohol and retin the carbolfuchsin stain, which is bright red. other bacteria lose the stain and are exposed to a methylene blue stain which is blue.
Outline how a laser scanning confocal microscope works
it moves a single spot of focused light across a specimen (point illumination) this causes fluorescence from the components labelled with a "dye". the emitted light from the specimen is filtered through a pinhole aperture. only light radiated from very close to the focal plane is detected.
Ammonia is too toxic for mammals to secrete so what happens???
its combined with co2 in the ornithine cycle to create urea
Draw a diagram of a prokaryotic cell, label the structures and annotate with their function.
label a diagram or something
What are laser scanning confocal microscopes used for?
laser scanning confocal microscopy is non-invasive and is currently used in the diagnosis of diseasesof the eye and being developed for use in endoscopic procedures. the fact that it can be used to see the distribution of molecules within cells means it is also used in the development of new drugs
What is the affect of excess alcohol over a long period of time?
leads to cirrhosis of the liver
the liver is made up of =
liver lobules
The larger 80s ribosomes are involved in the formation of...
more complex proteins
Explain why artefacts are more likely to be produced when preparing samples for electron microscopy than for light microscopy
more sample preparation in electron microscopy leads to more damage to specimen and damage results in artefacts
Why do images tend to have a low contrast in light microscopy?
most cells do not absorb a lot of light. resolution is limited by the wavelength of light and diffraction of light as it passes through the sample
hox genes in the head control development of...
mouthparts
what is cohesion
moves as one mass because the molecules are attracted to each other
the segments have...
multiplied over time and specialised to form different functions
nigrosin or congo red are...
negatively charged and are repelled by the negatively charged cytosol. these dyes stay outside of cells, leaving the cells unstained which then stand out against the stained backgroung (NEGATIVE STAIN TECHNIQUE)
Draw, label and annotate a diagram to show the structures present in a cholinergic synapse
p355 Memorise a diagram they all include these features: 1. Synaptic cleft 2. Presynaptic neurone 3. Postsynaptic neurone 4. Synaptic knob 5. Synaptic vesicles 6. Neurotransmitter receptors
Label a diagram of the human brain showing the location of the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland
p362 look and practice labelling 1. Main top bit is the cerebrum 2. Skull surrounds it all 3. Located just underneath the cerebrum is the corpus callosum which is worm shaped ish 4. Pituitary gland comes of the hypothalamus 5. Hypothalamus comes from the medulla oblongata 6. Cerebellum is a leaf shaped part under cerebrum 7. Spinal cord comes from comes down from the cerebellum
DNA in prokaryotes
packed differently. generally only have one molecule of DNA, a chromosome which is supercoiled to make it more compact. the genes on the chromosome are grouped into operons, menaing a number of genes are switched on or off at the same time
Prokaryotic cells have a cell wall made from
peptidoglycan also known as murein
Describe how ATP is involved in end-product inhibition of the enzyme phosphofructokinase.
phosphofructokinase is an enzyme in the metabollic pathway that breaks down glucose to make ATP. ATP inhibits the action of phosphofructokinase- so a high level stops more being made
Outline the structure and functions of pili in prokaryotic cells
pili are protein hairs that adhere to surfaces
CELLULOSE CELL WALL
plant cell walls are made of cellulose, a complex carbohydrate. they are freely permeable so substances can pass into and out of the cell through the cellulose wall. the cell walls of a plant cell gove it its shape. the contents of the cell press against the cell wall making it rigid. this supports both the individual cell and the plant as a whole. the cell wall also acts as a defence mechanism protecting the contents of the cell against invading pathogens
What is a Mesosome?
plasma membrane that folds into the cytoplasm and increases surface area
Crystal violet or methylene blue are...
positively charged dyes which are attracted to negatively charged materials in cytoplasm leading to staining of cell components
operons are far more commen in ...
prokaryotes than eukaryotes owing to the smaller and simpler structure of their genomes
compare DNA organisation in prokaryotes and eukaryotes
prokaryotic = cuircular dna called plasmids eukaryotic = only present in certain organelles such as chlorplasts and mitochondria
compare organelles in prokaryotes and eukaryotes
prokaryotic = non membrane-bound eukaryotic = both membrane bound and non membrane bound
Compare nucleus in prokaryotes and eukaryotes
prokaryotic = not present eukaryotic = present
compare cell wall in prokaryotes and eukaryotes
prokaryotic = peptidoglycan eukaryotic = chitin in fungi, cellulose in plants, not present in animals
compare cell surface membrane in prokaryotes and eukaryotes
prokaryotic = present eukaryotic = present
compare cell types in prokaryotes and eukaryotes
prokaryotic = unicellular eukaryotic = unicellular and multicellular
List 3 structural differences between prokaryotic cells and eukaryotic cells
prokaryotic cells: no nucleus / no membrane bound organelles, e.g. mitochondria / smaller / 70s ribosomes / plasmid / extra chromosomal DNA / peptidoglycan / murein cell wall
Why when preparing a wet mount should the refractive index (ability to bend light) of the medium by roughly the same as glass?
reduce / prevent, diffraction between liquid and glass and to prevent / reduce distortion of image
Name 2 methods of in situ conservation.
Wildlife reserves Marine conservation zones
Draw an energy-level graph to show how a reaction progresses with and without an enzyme present (the transition state model).
With an enzyme the peak is lower and it declines faster
What are transcription factors?
regulatory proteins that bind to specific DNA sequences to switch genes on or off (v important in control of development of body plans)
Example of a smear slide:
a sample of blood to view the cells in the blood
Alcohol>>>
a toxic substance that can damage cells. Its broken down by the liver into ethanol then acetic acid.
State the resolution and useful maximum magnification of light microscopes, TEM.
resolution- 0,2-0.5nm magnification- 500,000- x 2,000,000
State the resolution and useful maximum magnification of light microscopes,
resolution- 200nm magnification- x1500 - x2000
State the resolution and useful maximum magnification of SEMs
resolution- 3-10nm magnification- x100,000-500,000
The tonoplast is ...
selectively permeable which menas some small molecules can pass through it but others cannot
Why is drosophila a good model for development in humans?
similar/shared genes similar embryonic development shared ancestry similar cells and metabolism
What is a dry mount?
solid specimens are viewded whole or cut into very thin slices with a sharp blade (SECTIONING). the specimen is placed on centre of slide and a cover slip placed over the sample
What are pacinian corpuscles?
specific sensory receptors that detect mechanical pressure
sectioning =
specimens are dehydrated with alcohols and then placed in a mould with wax or resin to form a hard block. this can then be sliced thinly with a knife called a MICROTOME
staining =
specimens are often treated with multiple stains to show different structures
Describe the ionic bonds in the tertiary structure
these are the attractions between the negatively-charged R groups and positively-charged R groups on different parts of the molecule
What is the function of motor neurones?
these neurones transmit impulses from a relay neurone or sensory neurone to an effector such as a muscle or gland
Define sensory neurone function
these neurones transmit impulses from a sensory receptor cell to a relay neurone, motor neurone or the brain
Flagella Prokaryotes
thinner than eukaryotes and does not have 9+2 arrangement. the energy to rotate the filament that forms the flagellum is supplied from the process of chemiosmosis not from ATP as in eukaryotic cells
Identify the stages of mitosis (and the cell cycle) in photomicrographs or diagrams of cells
use an online quiz
metabolism produces...
waste products such as carbon dioxide and nitrogenous waste
urine is usually made up of...
water and dissolved salts urea other substances such as hormones and excess vitamins
Explain the biological significance of water's Reactivity
water can take part in reactions, takes part in hydrolysis and condensation reactions and is a major part in photosynthesis
Write an equation to link the water potential of a cell with its pressure potential and its solute potential.
water potential= pressure potential+ solute potential (kPa)
What are squash slides?
wet mount first prepared, then a lens tissue is used to gently press down the cover slip.
Excretion is
the removal of the waste products of metabolism in the body
Explain how the primary structure of a protein determines its tertiary structure.
the sequence of variable groups(the primary structure) and how they interact with each other through hydrogen and sulfide bonds will determine the secondary structure (alpha helices and beta pleated sheets) which will help determine the structure.
Define resolution
the shortest distance between the two objects that are still seen as two separate objects
how is a 2d image produced from laser scanning confocal microscope?
the spot illuminating the specimen is moved across the specimen
Define the term phosphorylation
The addition of a phosphate group to a molecule
Define the term phosphorylation
The addition of phosphate group to a molecule
Define ventilation
The air flow generated by breathing inhalation/exhalation
Define stroke volume
The amount of blood pumped by the left ventricle of the heart in one contraction
Define cardiac output
The amount of blood the heart pumps through the circulatory system in a minute
all structures in prokaryotic cell
1. DNA (bacterial chromosome) 2. flagellum 3. ribosome 4. plasma membrane 5. plasmid 6. cell wall 7. slime capsule 8. pili
State the properties and functions of lactose
1. A disaccharide made from alpha-glucose and galactose 2. It is the main sugar in milk 3. It is difficult to hydrolyse providing a slow release of sugars to baby
State the properties and functions of sucrose
1. A disaccharide made of alpha-glucose and fructose and is table sugar 2. In plants carbohydrate is moved from one region to another as sucrose.
State the properties and functions of maltose
1. A disaccharide made of two alpha- glucose molecules 2. Found in intestines and germinating seeds is an intermediate in the formation of starch.
Describe the range of values that Simpson's index of diversity can take and explain how to interpret the value calculated.
0-1 0 represents no diversity and 1 represents infinite diversity. closer to one the more diverse a habitat is and the greater it's ability to cope with change
Collagen
1. A fibrous protein 2. Found in animal connective tissues such as bone, skin and muscle 3. very strong molecule 4. Minerals can bind to the protein to increase rigidity
State the properties and functions of fructose
1. A hexose monosaccharide 2. It is the sugar in fruits and is used as a sugar substitute for diabetics
State the properties and functions of galactose
1. A hexose monosaccharide 2. It is used to make lactose ( the sugar in milk)
Define habitat
The area inhabited by a species
Describe the range of values that the "proportion of polymorphic gene loci" can take and explain how to interpret the value calculated.
0-1 The higher the number, the greater the proportion of polymorphic gene loci and so the greater the genetic biodiversity within a population.
Define the term "structural gene"
Genes that code for structural proteins or enzymes not involved in DNA regulatiomolecule of mRNA
Define the term gill filament
A thin projection from the gill arch creating a large SA- need a flow of water to keep them apart to expose th large SA
Define a codon
A three-base sequence of DNA or RNA that codes for an amino acid.
Describe the limitations of transplantation as a treatment for kidney failure
- risk of rejection (The antigens on the donor organ differ from the antigens on the cells of the recipient and the immune system is likely to recognise this) - Transplanted organs don't last forever with the average transplanted kidney functioning for around 9-10 years -Immunosuppressants are prescribed for the rest of the life
How does ADH affect the water retained or lost by the body
(More ADH) 1. The more ADH that is released, the more water channels are inserted into the membranes of the tubule cells 2. This makes it easy for more water to leave the tubules by diffusion resulting in the formation of a small amount of very concentrated urine. (Less ADH) 1. When ADH levels fall the reverse happens 2. Levels of cAMP fall, then the water channels are removed from the tubule cell membranes and enclosed in vesicles again 3. The collecting duct becomes impermeable to water once more, so no water can leave 4. This results in the production of large amounts of very dilute urine and maintains the water potential of the blood and tissue fluid.
Describe the role of the glomerulus
(Ultrafiltration) 1. The glomerulus is supplied with blood by a relatively wide afferent (incoming) arteriole from the renal artery 2. The blood leaves through a narrower efferent arteriole and as a result there is considerable pressure in the capillaries of the glomerulus 3. This forces the blood out through the capillary wall-acts as a sieve 4. Then the fluid passes through the basement membrane 5. The basement membrane is a made up of a network of collagen fibres and other proteins- second sieve 6. Most of the plasma contents can pass through the basement membrane but the blood cells and many proteins are retained in the capillary because of their size. >68000 molecular mass
crystal violet and potassium iodide are chemicals classed as irritants. crystal violet is also toxic. describe the precautions you should take when using these chemicals
-Avoid skin / eye contact -wear gloves / goggles
Describe and explain how the ultrastructure of the α- and β-cells in the islets of Langerhans is specialised to manufacture and secrete hormones.
-Cells specialised to manafacture proteins (e.g insulin & glucagon) will have many: -Ribosomes & RER for protein synthesis -Golgi apparatus (hormone prep and packaging into vesicles) -Secretory vesicles -mitochondria (ATP for active processes in the cell)
Explain the difference between contrast and resolution
-Contrast is difference in colour/shade between two objects -Resolution is the smallest distance between two objects that can still be seen as separate
Describe the constituents of the dialysis fluid and explain why this make up is necessary
1 . The dialysis fluid controls the loss of these substances- it contains normal blood plasma levels of glucose to ensure there is no net movement of glucose out of the blood 2. The dialysis fluid also contains normal plasma levels of mineral ions so any excess mineral ions in the blood move out by diffusion down a concentration gradient into the dialysis fluid, thus restoring the correct electrolyte balance of the blood 3. The dialysis fluid contains no urea meaning there is a very steep concentration gradient from the blood to the fluid and as a result much of the urea leaves the blood
Explain what is meant by the "all-or-nothing" response of neurones
1. A certain level of stimulus- threshold value- always triggers a response 2. If the threshold is reached an action potential will always be created 3. No matter how large the stimulus is, the same sized action potential will always be triggered 4. If the threshold is no reached, no action potential will be triggered
Explain why a change in the sequence of nucleotides of a gene can affect the function of the protein produced from that gene.
1. A change in a base sequence may change the amino acid the codon codes for 2. This leads to changes in the primary structure of the protein 3. But as it is degenerate it may mean the new codon still codes for the same amino acid so no change to protein
Define cell signalling
1. A complex system of intercellular communication 2. Where one cell releases a chemical which has an affect on another cell
Describe and explain 4 sources of evidence for the processes involved in translocation.
1, Microscopy allow us to see the adaptations of the companion cells for active transport 2. If mitochondria of companion cells are poisoned translocation stops 3. The flow of sugars in the phloem is 10000 times faster than it would be by diffusion alone suggesting an active process is driving the mass flow
Describe and explain 7 factors that affect the transmission of communicable diseases in animals.
1, Overcrowded living and working conditions 2. Poor nutrition 3. A compromised immune system- have AIDS or immuno-suppressant drugs after transplant surgery 4. Poor disposal of waste- provide breeding sites for vectors 5. climate change- introduces new vectors and new diseases- higher temps promote spread of malaria as the mosquito species is able to survive over a wider area 6. Culture and infrastructure- in some countries traditional medical practises can increase transmission 7. Socioeconomic factors- lack of trained health workers and insufficient public warning can affect transmission rates
Define the term "extrinsic protein"
1, Peripheral proteins that are present in one side of the bilayer. e.g. Enzymes, proteins that bind cytoskeleton to membrane. 2. They normally have hydrophillic R-groups on their outer surfaces and interact with the polar heads of the phospholipids or with intrinsic proteins
Draw a water molecule with charges
1. 2 hydrogen atoms and 1 oxygen atom arranged in a non-linear shape 2. Delta + charge on hydrogen and delta - on oxygen 3. Label the bond between hydrogen and oxygen as polar covalent bond
State the products from glycolysis
1. 4 molecules of ATP (net of 2)- used for energy 2. 2 reduced NAD- used in later stage to synthesise more ATP 3. 2 Molecules of pyruvate- Used in Link reaction of respiration
Describe how pre-mRNA is modified to produce mature mRNA, where this occurs and the benefit of this modification process
1. A cap (modified nucleotide) is added to the 5' end and a tail (a long chain of adenine nucleotides) is added to the 3' end 2. These both help to stabilise mRNA and delay degradation in the cytoplasm 3. The cap also aids binding of mRNA to ribosomes 4. Splicing occurs where the RNA is cut at specific points- the introns are removed and the exons are joined together. Both processes occur in the nucleus.
Draw, label and annotate a diagram of a potometer to show how it can measure transpiration rate.
1. A capillary tube with a measuring device attached- ruler etc 2. has a tap and fills the potometer with water- pushes the air bubble to the start 3. Cut a leafy shoot under water and transferred to the apparatus to avoid introducing air bubbles to the stem 4. Measure the rate of water uptake by measuring the distance the air bubble moves in a given time 5. You can vary conditions to see their affect on the rate of transpiration
Describe how the depolarisation of the membrane occurs and what is required for it to lead to an action potential.
1. A stimulus is detected by a sensory receptor which sets of these events 2. The energy from the stimulus triggers some sodium voltage gated ion channels to open, making the membrane more permeable to sodium ions 3. Sodium ions therefore diffuse into the axon- making the inside of the neurone less negative 4. The potential difference reaches threshold potential meaning an action potential will happen 5. This change in charge causes more voltage-gated sodium ion channels to open allowing more sodium ions to diffuse into the axon- positive feedback 6. When the potential difference reaches approx +40mV the voltage-gated sodium ion channels close and voltage-gates potassium ion channels open 7. Sodium can no longer enter the axon but the membrane is now more permeable to potassium ions
State the properties and functions of cellulose
1. A straight chain molecule of beta- glucose. 2. because it is straight chain the chains can lie parallel to each other. numerous hydrogen bonds link the parallel chains producing strength- means it provides structural support for cells
Write a sequence of bullet points to describe the sequence of electrical events of the heart beat.
1. A wave of electrical excitation begins in the SAN, causing the atria to contract and so initiating the heartbeat. 2. A layer of non-conducting tissue prevents the excitation passing directly to the ventricles 3. The electrical activity from the SAN is picked up by the AVN . 4.The AVN imposes a slight delay- allowing the atria to stop contracting before the ventricles start- before stimulating the bundle of His (bundle of conducting tissues made of purkyne fibres) which penetrate through the septum between the ventricles 5. The bundle of His splits into two branches and conducts waves of excitation to the apex (bottom) of the heart 6. At the apex the purkyne fibres spread out though the walls of the ventricles on both sides. 7. The wave of excitation triggers the contraction of the ventricles starting at the apex 8. Contraction at the apex allows more efficient emptying of the ventricles
How does ADH start the process of osmoregulation
1. ADH is released from the pituitary gland and carried in the blood to the cells of the collecting duct where it has its effect 2. The hormone does not cross the membrane of the tubule cells- it binds to receptors on the cell membrane and triggers the formation of cyclic AMP (cAMP) as a second messenger inside the cell
State the full name and the abbreviation of the hormone that controls the amount of water lost in urine, where it is produced and where it is stored
1. ADH- Anti-diuretic hormone 2. Produced- hypothalamus 3. Stored- Posterior pituitary gland
What are the products of the Calvin Cycle
1. ADP +P 2. RuBP 3. Triose phosphate 4. NADP+
Describe the structure of actin
1. Actin filaments have binding sites for myosin heads- actin-myosin binding sites 2. However, these binding sites are often blocked by the presence of another protein called tropomyosin which is held in place by the protein troponin 3. When a muscle is in a resting state the actin-myosin sites are blocked by tropomyosin. The myosin heads therefore cannot bind to the actin and the filaments cannot slide past each other.
What are the two types of protein filaments that make up myofibrils
1. Actin- the thinner filament. It consists of two strands twisted around each other 2. Myosin- the thicker filament. It consists of long rod-shaped fibres with bulbous heads that project to one side
Describe the difference between an absorption spectrum graph and an action spectrum graph.
1. Action spectrum graph- shows how the rate of photosynthesis varies at different wavelengths 2. Absorption spectrum graph- shows how different pigments absorb different wavelengths of light
Explain, in a paragraph and with a diagram, how substances can move across a membrane by active transport
1. Active transport is the movement of molecules or ions into or out of a cell from a region of low concentration to high concentration 2. It requires energy and carrier proteins. Metabollic energy is supplied by ATP 3. A molecule attaches to a carrier protein the protein changes shape and this moves the molecule across the membrane, releasing it on the other side
Describe the test for starch
1. Add a few drops of iodine dissolved in potassium iodide solution to the sample 2. If solution turns from yellow/brown to blue/black starch is present
Describe the test for proteins
1. Add sodium hydroxide to make the solution alkaline 2. Add copper 2 sulfate solution 3. If protein is present the solution is purple 4. If there's no protein, the solution will stay blue
State the complementary base pairing rules, name the bond that holds them together, and state the number of bonds that hold each pair together.
1. Adenine-Thymine/ Uracil form two hydrogen bonds 2. Cytosine- Guanine form 3 hydrogen bonds These rules means a small pyrimidine base always binds to a purine base.
State the 3 ways that ATP is regenerated in muscle fibres
1. Aerobic respiration 2. Anaerobic respiration 3. Creatine phosphate
Draw a table to outline the different ways 4 common antibiotics have their effect.
1. Affects cell walls made of peptidoglycan- burst 2. Enzymes- inhibit the metabolic pathways 3. Bacteria have a circular chromosome that is different to humans, so they can target the different DNA replication- prevent reproduction 4. Ribosomes- prevent protein synthesis 5. Make holes in the membrane altering the permeability
Describe how temperature affects the rate of photosynthesis
1. Affects the rate of enzyme-controlled reactions. 2. As temp increases, the rate of enzyme activity increases until the point at which the proteins denature. 3. An increase in temperature increases the rate of the enzyme controlled reactions in photosynthesis- carbon fixation etc.
Describe how haemoglobin's affinity for oxygen varies
1. Affinity for oxygen means the tendency a molecule has to bind with oxygen. 2. Haemoglobin's affinity for oxygen varies depending on the conditions it's in 3. Has high affinity in alveoli- high pO2 and low affinity in respiring tissue- low pO2
Describe 5 causes of genetic variation between individuals within a population
1. Alleles (with a gene for a particular characteristic, different alleles produce different affects. Individuals in a species population may inherit different alleles of a gene) 2. Mutations (Changes to the DNA sequence and therefore to genes can lead to changes in the proteins that are coded for) 3. Meiosis (gametes are produced by meiosis. Each gamete receives half the genetic content of a parent cell. The genetic material is mixed up by independent assortment and crossing over) 4. Sexual reproduction (offspring produced from tow individuals inherits genes form each of the parents) 5. Chance (different gametes are produced and in reproduction it is chance as to which two combine- individuals differ from siblings)
Explain how water stress limits the rate of photosynthesis but water availability itself is not considered to be a limiting factor.
1. Although it is required for photosynthesis it is never considered to be limiting because for the water potential to have become low enough to limit the rate of photosynthesis the plant will have already closed its stomata and ceased to photosynthesise. 2. Plants except those with adaptations to drought conditions are unlikely to survive these conditions.
*Explain how amphetamines will affect the nervous system
1. Amphetamines stimulate the release of more neurotransmitter from the presynaptic neurone 2. therefore it will bind to more receptors/more receptors activated on the postsynaptic membrane 3. threshold is reached and more action potentials generated in the post synaptic neurone 4. greater response to stimulus 5. neurotransmitter can only be released from the pre-synaptic membrane
List the two different polysaccharides that make up starch.
1. Amylopectin 2. Amylose
Describe the role of seed banks in maintaining biodiversity.
1. An example of a gene bank 2. Seeds are carefully stored so that new plants may be grown in the future 3. They are stored at low temperatures to maintain their viability, by slowing down the rate at which they lose their ability to germinate 4. Provides back up for the extinction of plants in the wild 5. But don't work for all plants as some seeds die when dried and frozen and most seeds in rain-forest fall into this category.
State 3 main types of activity for which cells require energy.
1. Anabolic reactions- synthesis of large molecules 2. Movement- e.g protein fibres in muscle cells that cause muscle contraction 3. Transportation of ions and molecules across the membrane.
Why is the secondary immune response quicker
1. Antigen presentation still happens 2. Clonal selection- many more cells 3. Clonal expansion- less needs to happen because there are already a lot of cells- memory cells- this is what saves the most time
Describe the process of cell mediated immunity.
1. Antigen presenting cells formed:- from phagocytosis, a viral infection or cancer 2. APC comes into contact with many different T helper cells - only T helper cells with complementary receptors to the antigens will be activated.- Clonal selection 3. T helper cells produce interleukins which stimulate other types of activated T-cell to clone by mitosis (as well as making the T helper cells themselves clone by mitosis)- Clonal expansion 4. T cells cloned may: - develop into T memory cells which give a rapid response if this pathogen invades again - Develop into T helper cells which either produce interleukins that stimulate phagocytosis or produce interleukins that stimulate B cells to clone by mitosis - Stimulate the development of a T killer cells that are specific for the presented antigen and then destroy infected cells
Describe the difference between the walls of arteries and veins
1. Arteries don't have valves 2. Arteries have a folded epithelium 3. Arterires have a thicker muscle/ elastic tissue/ tunica media 4. Arteries have thicker collgen/ tunica externa
Describe the processes of vasoconstriction and vasodilation, and how this affects blood flow through capillaries.
1. Arterioles have more smooth muscle but less elastin than arteries- little pulse surge but can constrict or dilate to control the flow of blood 2. When the smooth muscle in the arteriole contracts it constricts the vessel and prevents blood flowing into a capillary bed- vasoconstriction 3. When the smooth muscle relaxes- blood flows in the capillary bed- vasodilation
Explain how changing carbon dioxide concentration affects the concentration of RuBP, TP and GP in the Calvin cycle.
1. As CO2 is an essential substrate of the Calvin cycle, low concentrations will lead to reduced concentrations of GP (as there is less CO2 to be fixed) and TP 2. The concentrations of RuBP will increase as it is still being formed from TP but not being used to fix CO2- for a little until TP runs out.
Describe why deciduous plants lose their leaves as a respnse to abiotic stress
1. As light and temperature affect the rate of photosynthesis, seasonal changes have a big impact on the amount of photosynthesis possible 2. There is a point where the amount of glucose required for respiration to maintain the leaves, and to protect them against freezing is greater than the amount of glucose produced by photosynthesis 3. Alos, a tree that is in leaf is more likely to be damaged or blown over by winter gales.
Describe the process of shivering
1. As the core temperature falls the body may begin to shiver 2. This is the rapid, involuntary contracting and relaxing of the large muscles in the body 3. The metabolic heat from the exothermic reactions warm up the body instead of moving it and is an effective way of raising the core temperature
Explain why it is important that insulin is constantly being broken down by enzymes
1. As your blood-glucose concentration returns to the normal, you do not want to maintain a higher level of glycogenesis 2. So it needs to be constantly broken down to ensure you don't have too low a blood-glucose concentration
Describe how insulin is secreted by beta cells in response to a high blood glucose concentration
1. At normal blood glucose concentration levels, potassium channels in the plasma membrane of β cells are open and potassium ions diffuses out of the cell 2. When blood glucose concentration rises, glucose enters the cell by a glucose transporter 3. The glucose is metabolised inside the mitochondria, resulting in the production of ATP 4. The ATP binds to potassium channels and causes them to close. They are known as ATP-sensitive potassium channel 5. As potassium ions can no longer diffuse out of the cell, the potential difference reduces and depolarisation occurs 6. Depolarisation causes the voltage-gated calcium channels to open 7. Calcium ions enter the cell and cause secretory vesicles to release the insulin they contain by exocytosis
Draw and label a series of diagrams to describe the general reproductive cycle of a virus.
1. Attach to the host cell- requires receptor molecule on virus and molecule on cell surface- complementary shape- specific- infect 1 type of cell 2. Insertion of viral nucleic acid 3. Replication of viral nucleic acid in the cell 4. Synthesis of viral protein- using host cell's ribosomes 5. Assembly of virus particles 6. lysis of host cells (burst the host cell)
State the plant hormone in rooting powders and explain why rooting powders are useful.
1. Auxin affects the growth of both shoots and roots 2. Scientists have discovered that the application of auxin to cut shoots stimulates the production of new roots 3. This makes it easier to propagate new plants from plant cuttings 4. THis has made it much easier for horticulturists to develop cuttings to sell and for individuals taking their own cuttings 5. Many plants are now propagated on a large scale by micropropagation- plant hormones are essential in this process- they control the production of the mass of new cells and then the differentiation of the clones into tiny new plants.
Describe how auxins, such as IAA, lead to growth in the apical shoot
1. Auxins affect the plasticity of the cell wall- presence of auxins means the cell wall stretches more easily 2. Auxin molecules bind to specific receptor sites in the plant cell membrane, which triggers a second messenger system and cells pump H+ ions out, causing a fall in pH to about 5 which breaks hydrogen bonds within cellulose 3. This is the optimum pH for the enzymes needed to keep the walls very flexible and plastic 4. As the cells mature, auxin is destroyed 5. As the hormone levels fall, the pH rises so the enzymes maintaining plasticity become inactive 6. As a result the wall becomes rigid and more fixed in shape and size and the cells can no longer expand and grow
List 7 other commercial uses for named plant hormones
1. Auxins- can be used to produce seedless fruit 2. Ethene- is used to promote fruit dropping in plants such as cotton, walnuts and cherries 3. Cytokinins- are used to prevent ageing of ripened fruit and products such as lettuces and in micropropagation control tissue development 4. Gibberellins- can be used to delay ripening and ageing in fruit, to improve the size and shape of fruits and in beer brewing to speed up the malting process.
List 5 plant hormones and describe the effects of each of them.
1. Auxins- control cell elongation, prevent leaf fall (abscission), maintain apical dominance, involved in tropisms, stimulate the release of ethene, involved in fruit ripening 2. Gibberellin- cause stem elongation, trigger the mobilisation of food stores in a seed at germination, stimulate pollen tube growth in fertilisation 3. Ethene- causes fruit ripening, promotes abscission in deciduous trees 4. ABA- Maintains dormancy of seeds and buds, stimulates cold protective responses, stimulates stomatal closing 5. Cytokinins- promote cell division
Apart from myelination what are the two other factors that affect the speed of transmission
1. Axon diameter- The bigger the axon diameter, the faster the impulse is transmitted. This is because there is less resistance to the flow of ions in the cytoplasm, compared with those in a smaller axon 2. Temperature- The higher the temperature, the faster the nerve impulse. This is because ions diffuse faster at higher temperature. Only occurs to about 40 degrees as higher causes the proteins to become denatured
Describe the difference in structure between a myelinated and non-myelinated neurone and how this affects the speed a nerve impulse in transmitted
1. Axon of a myelinated neurone is covered in myelin 2. myelin is an electrical insulator 3. the sheath is formed by Schwann cells growing around the axon several times 4. there are gaps in the myelin sheath known as nodes of Ranvier 5. electrical impulse moves in a series of 'jumps' from one node to the next/saltatory conduction 6. impulse transmitted much faster than along an unmyelinated axon
Describe the process of humoral immunity.
1. B lymphocytes have antibodies on their cell surface membrane which are specific to only one antigen 2. When a pathogen enters the body, a B cell with complementary antibodies will bind to the antigens on the pathogen - it will engulf and process the antigen to become an APC. 3. Clonal selection- Selection of the appropriate B cell by the T helper cells to be cloned- T cell binds to the B cell APC 4. Clonal expansion- T helper cell produces interleukins to activate the B cells which then divide by mitosis to produce clones 5. B cells differentiate to form plasma and B effector cells and B memoery cells 6. Plasma cells secrete antibodies which are specific to the antigen which help to destroy the pathogen 7. Memory cells remain in circulation to provide a secondary response- faster response to subsequent exposure
Describe the layout of living organisms
1. Body plans are usually represented as cross-sections through the organisms showing the fundamental arrangement of tissue layers 2. Diploblastic animals- 2 primary tissue layers 3. Triploblastic animals- 3 primary tissue layers 4. All animals are segmented- the segments have multiplied over time and are specialised to perform different functions 5. Hox genes in the head control the development of mouth-parts 6. Hox genes in the thorax control development of wings, limbs or ribs 7. The individual vertebrae and associated structures have all developed from segments in the embryo called somites which are directed by Hox genes to develop in a particular way depending on their position in the sequence
Describe the process of humoral immunity.
1. B lymphocytes have antibodies on their cell surface membrane which are specific to only one antigen, 2. When a pathogen enters the body, a B cell with complementary antibodies will bind to the antigens on the pathogen - it will engulf and process the antigen to become an APC. 3. Clonal selection- Selection of the appropriate B cell by the T helper cells to be cloned- T cell binds to the B cell APC 4. Clonal expansion- T helper cell produces interleukins to activate the B cells which then divide by mitosis to produce clones 5. B cells differentiate to form plasma and B effector cells and B memoery cells 6. Plasma cells secrete antibodies which are specific to the antigen which help to destroy the pathogen 7. Memory cells remain in circulation to provide a secondary response- faster response to subsequent exposure
Describe the roles of the distal convoluted tubule and explain how it can perform these roles
1. Balancing the water needs of the body takes place in the distal convoluted tubule and the collecting duct 2. These are the area where the permeability of the walls of the tubules varies with the levels of ADH 3. The cells lining the distal convoluted tubule also have many mitochondria so they are adapted to carry out active transport 4. If the blood lacks salt, sodium ions will be actively pumped out of the distal convoluted tubule with chloride ions following down an electrochemical gradient 5. Water can also leave the distal tubule, concentrating the urine, if the walls of the tubule are permeable in response to ADH 6. The distal convoluted tubule also plays a role in balancing the pH of the blood
What do baroreceptors detect and how does this affect heart rate
1. Baroreceptors present in the aorta and carotid artery wall detect changes in pressure 2. If blood pressure is too high, impulses are sent to the medulla oblongata centre which decreases heart rate 3. The medulla oblongata sends impulses along the parasympathetic neurones to the SAN which decreases the rate at which the heart beats. This reduces blood pressure back to normal 4. If blood pressure is too low, impulses are sent to the medulla oblongata centre which increases heart rate 5. The medulla oblongata sends impulses along sympathetic neurones to SAN which increases the rate at which the heart beats. This increases blood pressure back to normal
Explain why glycolysis is the process that continues in anaerobic respiration whereas the link reaction, the Krebs cycle and oxidative phosphorylation all stop.
1. Because NAD is produced, so a small amount of glycolysis can take place 2. But there is not enough to be used in Krebs and Link so they have nothing to accept hydrogen atoms 3. No oxygen for oxidative phosphorylation
Explain why alpha-glucose links together to form starch whereas beta-glucose links together to form cellulose.
1. Because beta-glucose has a hydroxyl group pointing up. This means the hydroxyl group on carbon-1 and carbon-4 would be too far way from each other to react 2. So the only way beta-glucose can join together and from a polymer is if alternate beta-glucose molecules are turned upside down. 3. This means that the polysaccharide is unable to coil or form branches so is a straight chain molecule- cellulose 4. Starch has branches and coils- amylopectin 1-6 bonds as well as 1-4 glycosidic bonds
Suggest why the Influenza vaccine needs to be redeveloped and people need to be revaccinated each year.
1. Because the antigens on the surface of the influenza virus change regularly forming new strains of the virus 2. Memory cells produced from the vaccination with one strain of the flu will not recognise other strains with different antigens- immunologically different
Explain the significance of where a line of best fit crosses the x-axis in a graph showing how external concentration affects mass change in plant tissues.
1. Because the point where the line crosses the x axis is the point where there was no osmosis. 2. So that means that it has the same water potential in and out of the cell- tells you concentration inside the cell.
Explain why the yield of ATP from anaerobic respiration is much lower than the yield from aerobic respiration
1. Because there is no oxygen to act as the final electron acceptor at the end of the electron transport chain in oxidative phosphorylation, the flow of electrons stop. This means the synthesis of ATP by chemiosmosis also stops 2. As the flow of electrons along the electron transport chain has stopped, the reduced NAD and reduced FAD are no longer able to be oxidised because there is nowhere for the electrons to go 3. This means NAD and FAD cannot be regenerated and so the decarboxylation and oxidation of pyruvate and the Krebs cycle comes to a halt as there are no coenzymes available to accept the hydrogen atoms being removed 4. Glycolysis would come to a halt due to the lack of NAD if it were not for the process of fermentation 5. There is no transport chain which is what generates the majority of ATP in aerobic respiration.
Describe the properties a stain needs to have to be useful for light microscopy.
1. Bind to other molecules- differential staining - bind to certain parts of the cell 2. liquid- and be able to get through cell membrane. 3. shouldn't damage the cell 4. very intense colour- to be able to colour something in small amounts.
What are the sinusoids
1. Blood from hepatic artery and hepatic portal vein is mixed in spaces called sinusoids which are surrounded by hepatocytes 2. This mixing increases the oxygen content of the blood from the hepatic portal vein, supplying the hepatocytes with enough oxygen for their needs 3. They contain Kupffer cells
List the factors that need keeping constant inside cells
1. Blood-glucose concentration 2. Internal temperature 3. Water potential 4. Cell pH
Give 4 examples of anatomical adaptations
1. Body covering- hair, scales feathers- help to fly, stay warm 2. Camouflage- outer colour which allows an organisms to blend into its environment- make it harder for predators to spot 3. Teeth- shape and type are related to an animal's diet 4. Mimicry- copying another animals appearance or sounds allow harmless animals to fool predators into thinking it's poisonous or dangerous.
Summarise the light-independent stage of photosynthesis and state where this occurs.
1. Calvin cycle takes place in the stroma 2. CO2 diffuses into stroma from the atmosphere through the stomata and spongy mesophyll layer 3. They CO2 combines with the 5-carbon molecules ribulose bisphosphate(RuBP).- carbon fixation as the carbon in the CO2 is fixed 4. Enzyme ribulose bisphosphate carboxylase RuBisCO catalyses the carbon fixation producing an unstable 6-carbon intermediate 5. RuBisCO is an inefficient enzyme as it is competitively inhibited by oxygen so a lot is needed to carry out photosynthesis 6. The unstable 6-carbon compound formed immediately breaks down forming two 3-carbon glycerate 3-phosphate (GP) molecules 7. Each GP molecule is converted to another 3-carbon molecule, triose phosphate (TP), using a hydrogen atom from reduced NADP and energy from ATP (ATP forms ADP + P). (TP is GP with hydrogens) 8. Triose phosphate is a carbohydrate the majority of it is recycled to regenerate RuBP so that the Calvin Cycle can continue 9. Triose phosphate is the starting point for many complex biological molecules e.g. carbs, lipids, proteins and nucleic acids.
Describe how stem cells may be useful for treating burns.
1. Can be grown on biodegradeable meshes to produce new skin 2. Quicker than skin grafts
List the 4 main categories of biological molecule.
1. Carbohydrate 2. Lipids 3. Proteins 4. Nucleic acids
Describe the role hepatocytes play in the control of blood glucose concentration
1. Carbohydrate metabolism 2. When blood glucose levels rise, insulin levels rise and stimulate hepatocytes to convert glucose to the storage carbohydrate glycogen 3. When blood glucose levels start to fall, the hepatocytes convert the glycogen back to glucose under the influence of the hormone glucagon
State the typical respiratory quotients for carbohydrates, proteins and lipids.
1. Carbohydrates= 1.0 2. Proteins = 0.9 3. Lipids= 0.7
Name the 3 main metabolic waste products in mammals, describe where they come from and where they are excreted
1. Carbon dioxide- One of the waste products of cellular respiration which is excreted from the lungs 2. Bile pigments- Formed from the breakdown of haemoglobin from old red blood cells in the liver. They are excreted in the bile from the liver into the small intestine via the gall bladder and bile duct. They colour faeces. 3. Nitrogenous waste products (urea)- formed form the breakdown of excess amino acids by the liver. Urea is excreted by the kidneys in the urine
Describe the fate of the hydrogen ions produced when carbonic acid dissociates into hydrogen ions and hydrogen carbonate ions, and describe the two positive consequences of this outcome.
1. Cause oxyhaemoglobin to unload so that the haemoglobin can take up H+ ions. 2. Forms haemoglobinic acid 3. Stops the H+ ions from increasing the cell's acidity
What are the 3 key features of mammalian neurones?
1. Cell body 2. dendrons 3. axons
Describe the patterns of lignification in xylem and state its function.
1. Cells walls are thickened with lignin which helps to support the walls and stops them collapsing inwards 2. It can be in spirals or as distinct rings 3. These patterns allow flexibility and prevents the stem form breaking 4. As the cell gets older the amount of lignin increases
Describe the similarities and differences between synapses and neuromuscular junctions.
1. Cellular connection made in a synapse is with a neurone but with neuromuscular junction it is a muscle cell 2. Effect on post-synaptic cell- Synapse is action potential, Neuromuscular junction leads to depolarisation of sarcolemma and contraction of cell 3. Shape of post-synaptic membrane- synapse has a normal smooth membrane, neuromuscular junction is wiggly membrane 4. Neurotransmitter- synapse has acetylcholine but can use other stuff, Neuromuscular junction has just acetylcholine 5. Everything else is the same. e.g role of vesicles is both to store acetylcholine. And they remove the neurotransmitter in the same way.
Outline how a cell becomes specialised.
1. Certain conditions stimulate cells to differentiate into specialised 2. During differentiation certain genes are permanently switched off and some are switched on. 3. The genes which are switched on produce proteins and these proteins alter the metabolism and structure of the cell to make it specialised- often permanent change
Draw a flow chart to outline the processes (and components) involved in negative feedback
1. Change away from the optimum/norm is detected by receptors 2. Signals are sent to effectors sometimes via a control centre 3. Effectors initiate a response 4. Conditions return to optimum/ norm
Explain the difference between a channel protein and a carrier protein and link this to their functions.
1. Channel proteins are only involved in passive They provide a hydrophilic channel for polar molecules and ion. 2. Carrier proteins are involved in both active and passive transportation. it often involves the shape of the protein changing.
Describe a step by step method to investigate how one environmental factor affects the rate of photosynthesis.
1. Choose the factor which can be recorded useing the data loggers. 2. Use sodium hydrogen carbonate as the source of CO2 3. Pond weed should be kept in the dark- so it can finish photosynthesising and use up its reactants, 4. The apparatus should be left to equilibriate for 10 minutes before readings are taken. 5. The oxygen sensor may need to be calibrated using the oxygen concentration of air. 6. The software can be used to take readings at desired intervals for the required time length.
Show the chemical symbol and biological processes chloride ions are responsible for
1. Cl- 2. Involved in the chloride shift which helps to maintain the pH of the blood during gas exchange 3. Acts as a cofactor for the enzyme amlyase 4. Also involved in some nerve impulses
Name and describe 2 ways of measuring species biodiversity.
1. Counting the number of species present- species richness- but doesn't take into account the number of individuals present. 2. Simpson's Index of Diversity- better as it takes into account both species richness and species evenness.
Describe how creatine phosphate regenerates ATP
1. Creatine is stored in muscle 2. To form ATP, ADP has to phosphorylated- a phosphate group has to be added 3. Creatine phosphate acts as a reserve supply of phosphate, which is available immediately to combine with ADP rapidly, but the store of phosphate is used up quickly 4. As a result this is used for short bursts of vigorous exercise such as a tennis serve 5. When the muscle is relaxed, the creatine phosphate store is replenished using phosphate form ATP .
Name two sites of chemiosmosis in cells.
1. Cristae 2. grana- thylakoid membrane
Describe how cartilage is specialised for its function
1. Connective tissue found in ears, nose and ends of bones. 2. Contains fibres of the proteins elastin and collagen. 3. It is a firm, flexible connective tissue composed of chondrocyte cells embedded in extracellular matrix. 4. Prevents the ends of bones from rubbing together and causing damage.
Describe the structure of the alveoli
1. Consist of layer of thin, flattened epithelial cells along with some collagen and elastic fibres- allows the alveoli to stretch as air is drawn in. When they return to resting size air is squeezed out- elastic recoil of lungs 2. Large SA 3. Thin layers- one cell thick 4. Good blood supply- surrounded by capillaries to maintain steep conc gradient. 5. Good ventilation 6. Inner surface is covered by thin layer of solution of water, salts and lung surfactant- surfactant allows alveoli to remain inflated and Oxygen is dissolved in the water before diffusion into the blood
Describe the role of mitochondrial cristae in the process of oxidative phosphorylation.
1. Contains electron transport chain for generating ATP 2. Projections- cristae- increase surface area available for oxidative phosphorylation
Describe 7 methods of active management in wildlife reserves.
1. Controlled grazing (only allow livestock to graze a particular area of land for a certain period of time to allow species time to recover) 2. Restricting human access (providing paths so plants aren't trampled) 3. Controlling poaching (creating defences to prevent access, issuing fines etc) 4. Feeding animals (help to ensure more organisms survive to reproductive age) 5. Reintroduction of species (adding species to areas that have become locally extinct, or whose numbers have decreased rapidly) 6. Culling or removal of invasive species (invasive species are not native and have negative effects on the economy, environment or health. They compete with native species for resources) 7. Halting succession (protect habitat such as heath from becoming woodland through controlled grazing)
Explain how to calculate breathing rate from spirometer trace.
1. Count how many peaks there are in tidal volume section of the graph- number of breaths 2. Read off x axis to see the time it took for thast number of breathes 3. Then calculate breathes per minute
State 2 ways in which meiosis produces variation.
1. Crossing over of chromatids during prophase 1. 2. Independent assortment of chromosomes
Describe 5 methods associated with agriculture which affect biodiversity.
1. Deforestation 2. Removal of hedgerows- enables them to use large machinery and frees up land. This reduces the number of plant species present in an area and destroys the habitat of animals. 3. Use of chemicals such as pesticides and herbicides- kills pests which reduces species diversity directly and indirectly by destroying the food source of other organisms. 4. Monoculture- many farms specialise in the production of only one crop. This lowers the biodiversity as only one species of plant is present. Few animal species will be supported by only one type of plant- low overall biodiversity levels.
Name and describe the 4 types of chromosome mutation
1. Deletion - a section of chromosomes breaks off and is lost within the cell 2. Duplication - sections get duplicated on a chromosomes 3. Translocation - a section of one chromosome breaks off and joins another non-homologous chromosome 4. Inversion - a section of chromosome breaks off, is reversed and then joins back onto the chromosome
Describe 3 ways of collecting data using a frame quadrat (that could be applied to either random or non-random sampling).
1. Density- Count the number of plants in a quadrat- density per square metre- absolute measure not an estimate 2. Frequency- individual members of a species are hard to count like grass or moss. Using small grids within a quadrat count the number of squares a particular species is present in. 3. Percentage cover- for speed as lots of data can be collected quickly. Useful when a particular species is abundant or difficult to count. An estimate by eye of the area withing a quadrat that a species covers.
Describe the role of T killer cells
1. Destroy pathogens carrying the antigen 2. Produce a chemical called perforin which kills the pathogen by making holes in the cell membrane so it is freely permeable
State the two main ways in which kidney failure is treated
1. Dialysis 2. Transplant
Explain, in a paragraph and how substances can move across a membrane by simple diffusion.
1. Diffusion happens because gas or liquid particles have kinetic energy. 2. The movement is random and an unequal distribution of particles will eventually become an equal distribution. 3. It is a passive process and it will continue until there is a concentration equilibrium between the two areas.
State 3 examples of organ systems in animals and for each describe their function.
1. Digestive system- breaks down large insoluble molecules to small soluble ones, absorbs nutrients into blood, retains water and remove undigested material 2. Cardiovascular system- Moves blood around the body 3. Gaseous exchange system- brings air into body so oxygen an be extracted for Respiration and CO2 can be expelled
Explain why it may not be possible to release some captively bred organisms back into the wild.
1. Diseases (there may be a loss of resistance ot local diseases in captive-bred populations. New diseases might exist in the wild, to which captive animals have yet to develop resistance) 2. Behaviour (Much behaviour has to be learnt- early stages of reintroduction monkeys starved to death as they had no concept of having to search for food) 3. Genetic races (The genetic make-up of captive animals can become so different form the original population hat the two populations cannot interbreed) 4. Habitat (in many cases the natural habitat must first be restored to allow captive populations to be reintroduced. If only a small habitat exists it is likely that there are already as many individuals as that habitat can support. Introduction of new individuals can lead to tensions as individuals fight for limited territory and resources such as food)
Draw and annotate a graph of an action potential conducting down an unmyelinated axon
1. Distance along the bottom and action potential on the y axis 2. Reverse of membrane potential to time 3. Hyperpolarisation first, then repolarisation, then depolarisation 4. Opposite because as you go along an axon the part closest will be furthest through its action potential
Describe the test for non-reducing sugars
1. Do not react with Benedict's solution so the solution will remain blue after warming 2. If you then add dilute HCl and heat in a water bath 3. Then neutralise it with sodium hydrogen carbonate 4. This hydrolyses the sugar into monosaccharides so gives a positive result
Describe the potential benefits of stem cell treatment for Type 1 diabetes over insulin injection or whole pancreas transplantation
1. Donor availability would not be an issue- stem cells could produce an unlimited source of new β cells 2. Reduced likelihood of rejection problems as embryonic stem cells are generally not rejected by the body. Stem cells can also e made by somatic cell nuclear transfer 3. People no longer have to inject themselves with insulin
Draw, label and annotate a diagram of a chloroplast.
1. Double membrane structure 2. The fluid enclosed is called the stroma 3. Thylakoids- network of membranes, provides large surface area needed for enzymes, proteins and pigments in photosynthesis 4. Granum- several thylakoids stacked together 5. Lamellae- membranes which join the grana 6. Chlorophyll- in the grana 7. Contain DNA and ribosomes
Explain how to find the rate of reaction from a curved graph
1. Draw a tangent at the point needed. 2. Calculate the gradient of the tangent- change in y/ change in x 3. Work out units by doing units of y/ units of x e.g cm3 /s = cm3s-1
Draw a diagram to show how a much higher oxygen saturation of the blood can be achieved by a countercurrent exchange system as compared to a parallel exchange system.
1. Draw two graphs with distance along gill plate as x-axis and % saturation of oxygen as y. 2. For counter current there are two parallel line next to each other but with arrows the opposite way 3. For parallel two curved arrows which start at opposite ends of the y axis and then pull together and almost meet .
Outline the route water takes through a plant.
1. Drawn from the root hair cells by osmosis down the water potential gradient 2. Up the plant to the leaves down the water potential gradient- soil around the roots have higher water potential than leaves
Describe how a respirometer can be used to provide information about which respiratory substrate might be being used by an organism at a particular point, and explain why there may be alternative explanations for an organisms RQ value.
1. During normal activity the RQ is in the range of 0.8 to 0.9 showing that carbohydrates and lipids (and probably some proteins) are being use as respiratory substrates 2. During aerobic respiration, the RQ increases above 1.0 although this is not easy to measure as the point at which anaerobic respiration begins is not easy to pinpoint 3. You can use respirometer to measure the RQ which can tel you what is being used.
What are myofibrils
1. Each muscle fibre contains many myofibrils 2. They are long cylindrical organelles made of proteins and specialised for contraction 3. On their own they provide almost no force but collectively they are very powerful. 4. Myofibrils are lined up in parallel to provide maximum force when they all contract together
Describe the role of sensory areas, association areas and motor areas of the cerebral cortex
1. Each sensory area within the cerebral hemispheres receives information from receptor cells located in sense organs 2. The size of the sensory area allocated is in proportion to the relative number of receptor cells present in the body part 3. The information is then passed on to other areas of the brain known as association areas, to be analysed and acted upon 4. Impulses come into the motor areas where motor neurones send out impulses, e.g to move skeletal muscles 5. The size of the motor area allocated is in proportion to the relative number of motor endings in it 6. The main region which controls movement is the primary motor cortex located at the back of the frontal lobe
Compare the relative proportions of elastin fibres, smooth muscle and collagen in the aorta, medium-sized arteries and arterioles and relate these to their function.
1. Elastin fibres- Aorta > medium sized artery > arteriole 2. Smooth muscle-Medium sized artery > arteriole >aorta 3. Collagen- aorta > arteriole> medium sized artery Arterioles
Describe the role of the loop of Henle
1. Enables mammals to produce urine more concentrated than their own blood 2. Different areas of the loop have different permeabilities to water- central to the way it functions 3. It acts as a countercurrent multiplier using energy to produce concentration gradients that result in the movement of substances such as water from one area to another 4. Cells use ATP to transport ions using active transport and this produces a diffusion gradient in the medulla 5. The changes that take place in the descending limp of the loop of Henle depend on the high concentration of sodium and chloride ions in the tissue fluid of the medulla that are the result of events in the ascending limb of the loop
There are two models for the mechanism of enzyme action. Outline how changes in temperature can affect these mechanisms of lipase action
1. Enzyme-substrate complex is formed and then enzyme-product complex formed 2. Product will leave the active site. 3. Lock and key= shape of substrate and enzyme's active site are complementary and so enzyme is specific. 4. Induced fit= enzyme active site changes shape to accommodate substrate once substrate binds. 5. Increase in temperature increases kinetic energy of molecules which results in more successful collisions, so more enzyme-substrate complexes form. 6. Decrease in temperature reduces kinetic energy of molecules, results in fewer successful collisions so fewer enzyme substrate complexes are formed. 7. Enzymes have an optimum temperature 8. An increase in temperature affects the bonds involved in the tertiary structure, which changes the shape of the active site. 9. This prevents substrate binding to active site. 10. High temperature results in denaturing. 11. Affects of high temperature are irreversible 12. Affects of low temperature are reversible
Describe the steps in the process of apoptosis
1. Enzymes inside the cell break down important cell components such as proteins in the cytoplasm and DNA in the nucleus 2. The cell's contents are broken down it begins to shrink and the nucleus condenses and the cell forms blebs 3. Proteins start to breakdown the cell compartments and enzymes break down the nucleus 4. The DNA fragments 5. The cell fragments are engulfed by phagocytes and digested.
Describe the role of protein kinases in regulation of gene expression or protein activity
1. Enzymes that catalyse the addition of phosphate groups to proteins 2. The addition of a phosphate group changes the primary structure and so the function of a protein 3. Many enzymes are activated by phosphorylation 4. Protein kinases are therefore important regulators of cell activity 5. Protein kinases are themselves often activated by the secondary messenger cAMP.
Explain why it is important for erythrocytes and neutrophils to be constantly produced
1. Erythrocytes- lack of nucleus and organelles means they only have lifespan of around 120 days- need to be constantly replaced. 2. Neutrophils- They only live for around 6 hours so need to be replaced constantly
Describe the role of plant hormones in controlling the ripening of fruits.
1. Ethene is incolved in the ripening of climacteric fruits- fruits that continue to ripen after they have been harvested. E.g bananas, tomatoes, mangoes and avocados 2. Their ripening is linked to a peak of ethene production triggering a series of chemical reactions including a greatly increased respiration rate 3. Non climacteric fruits ( oranges, strawberries and watermelon) do not produce large amounts of ehten and do not ripen after picking 4. The effect of ethene can easily be seen if part of a bunch of green bananas is put into a bag with a single ripe banana 5. The bunch with the ripe banana will ripen faster than the rest of the bunch, even if the temp is exactly the same in both cases. Ethene from ripe banana stimulates rapid ripening of green ones.
Explain the benefits of using plant hormones to control ripening of fruit for sale in shops
1. Ethene is widely used commercially in the production of perfectly ripe climacteric fruit for greengrocers and supermarkets 2. These fruit are harvested when they are fully formed but long before they are ripe, and then cooled, stored and transported 3. Then unripe fruit is hard and much less easily damaged during transport than ripe versions 4. When the fruit are needed for sale, they are exposed to ethene gas under controlled conditions 5. This ensures that each batch of fruit ripens at the same rate and are all at the same stage to be put on the shelves for sale to the public 6. This prevents a lot of wastage of fruit during transport and increases the time available for them to be sold.
name and write the functions of the parts of a compound light microscope
1. Eye piece- is what you look through and it magnifies the object 10x 2. Scanning lens- It is used in preliminary observation and magnifies 4x 3. Low power objective lens- magnifies 10x and gives the middle amount of detail. 4. High power objective lens- magnifies 40x and gives the most amount of detail 5. Stage clips- used to secure the slide and hold it in place 6. Stage- stand above the the light source for the glass slide 7. Arm- where you hold a microscope 8. Condenser- used to vary the intensity of the light projected 9. Coarse- roughly puts things into focus and should only be used with the scanning lens 10. Fine adjustment- Puts things into full focus and should only be used with the low and high power objectives lenses 11. Illumination- projects light onto the slide.
Suggest two ways in which the use of antibiotics may be increasing the likelihood of resistance evolving.
1. Farmers using antibiotics in animal feed to prevent animals losing condition due to infection 2. Over subscription to antibiotics
Draw and annotate oxygen dissociation curves to show the difference between fetal and adult human haemoglobin.
1. Fetal haemoglobin has a higer affinity for oxygen than adult's. 2. Important has fetus gets oxygen from its' mothers blood across the placenta 3. By the time mother's blood reaches the placenta, its oxygen saturation has decreased beacause some has been used up by the mother's body. 4. The placenta has a low pO2, so adult haemoglobin will unload its oxygen. 5. The fetus haemoglobin has to have a higher affinity than adult haemoglobin- takes up oxygen in lower pO2 than adult haemoglobin. 6. Fetal haemoglobin graph is to the left of the adult curve.
Describe involuntary (smooth) muscles structure and function
1. Fibre appearance- non-striated 2. Control- involuntary 3. Arrangement- no regular arrangement- different cells can contract in different directions 4. Contraction speed- slow 5. Length of contraction- can remain contracted for a relatively long time 6. Structure- muscles showing no cross striations are called non-striated or unstriped muscles. Fibres are spindle shaped and uninuleated
Describe cardiac muscles structure and function
1. Fibre appearance- specialised-striated 2. Control- involuntary 3. Arrangement- cells branch and interconnect resulting in simultaneous contraction 4. Contraction speed- intermediate 5. Length of contraction- intermediate 6. Structure- cardiac muscle does show striations but they are much fainter than those in skeletal muscle. Fibres are branched and uninucleated
Describe skeletal muscles structure and function
1. Fibre appearance- striated 2. Control- conscious (voluntary) 3. Arrangement- regularly arranged so muscle contracts in one direction 4. Contraction speed- rapid 5. Length of contraction- short 6. Structure- muscles showing cross striations are known as striated or striped. Fibres are tubular and mulitnucleated
Define collecting duct
1. Final part of the tubule that passes through the renal medulla and the place where hypertonic urine is produced if needed 2. The permeability of the walls is affected by ADH levels and it is the main site of water balancing
Describe how to use a calorimeter in a quantitative test for reducing sugars
1. First calibrate the colorimeter using distilled water 2. Carry out a serial dilution to get a range of known glucose concentrations 3. Carry out the benedict's test on these solutions - use the same amount of Benedict's solution in each case 4. Remove any precipitate 5. % transmission of each solutions of glucose is measured using the colorimeter 6. Plot a calibration curve of absorbance over concentration of glucose.
Explain the releasing of calcium ions stage in the sliding filament hypothesis of muscle contraction.
1. First the events at the neuromuscular junction occur causing depolarisation 2. The depolarisation of the sarcolemma travels deep into the muscle fibre by spreading through the T-tubules. These are in contact with the sarcoplasmic reticulum 3. The sarcoplasmic reticulum contains stored calcium ions which it actively absorbs from the sarcoplasm 4. When the action potential reaches the sarcoplasmic reticulum it stimulates calcium channels to open. 5. The calcium ions diffuse down their concentration gradient flooding the sarcoplasm with calcium ions.
Explain how RuBP is regenerated in the Calvin cycle.
1. For one glucose molecule to be produced 6 CO2 have to enter the Calvin cycle, resulting in 6 turns of the cycle 2. This produces 12 TP molecules two of which are removed to produce glucose molecule 3. 10 TP molecules are left- they are recycled to regenerate 6 RuBP molecules 4. This uses ATP for energy (maybe provides phosphate).
Explain how the fossil record provides evidence for evolution
1. Fossils of simpler organisms are found in the oldest rocks, whilst fossils of more complex organisms are found in more recent rocks 2. Sequence in which organisms are found matches their ecological links with each other-plant fossils found before animal fossils 3. Study similarities in anatomy of fossil organisms- shows how closely related organisms have evolved from the same ancestor
Describe how gibberellins lead to growth.
1. Gibberellins affect the length of internodes- regions between the leaves on a stem. Stimulate elongation (by loosening cell walls) and cell division (by stimulating production of protein that controls cell cycle) 2. Discovered as were produced by fungus which affects rice. The affected seedlings grew extremely tall and thin. Scientists investigated rice and isolated chemicals- gibberellins which produce the same spindly growth in the plants 3. It was then discovered that plants themselves produce the same compounds 4. Plants that have short stems produce few or no gibberellins 5. Scientists have bred many dwarf varieties of plants where the gibberellin synthesis pathway is interrupted 6. Without gibberellins plant stems are much shorted 7. This reduces waste and makes the plants less vulnerable to damage by weather and harvesting
Draw and label a diagram of a nephron
1. Glomerulus a bed of capillaries fed by the renal artery - surrounded by Bowman's capsule 2. This leads to Proximal convoluted tubule 3. This goes down to the descending limb of the Loop of Henle (goes thin) 4. This leads to the Loop of Henle which curves up to the ascending limb of loop of Henle (thicker) 5. This goes up to the distal convoluted tubule 6. Joins to the collecting duct which leads to the pelvis of the kidney
State the molecules/conditions required for glycolysis
1. Glucose 2. 2 molecules of ATP 3. Co-enzyme NAD 4. Phosphate ions 5. No oxygen required
Describe what reagent test strips are with an example of how they are used.
1. Glucose can also be tested for using test strops covered in reagent 2. They change colour if glucose is present 3. The colour change can be compared with a colour chart to give an indication of concentration of glucose present
When is lactose used as a respiratory substrate for Escherichia coli
1. Glucose is easier to metabolise and is the preferred respiratory substrate 2. If glucose is in short supply, lactose can be used as a respiratory substrate. 3. Different enzymes are needed to metabolise lactose
State the effect glucagon has on cells.
1. Glycogenolysis- the liver breaks down its glycogen store into glucose and releases it backs into bloodstream 2. Reducing the amount of glucose absorbed by the liver cells 3. Increasing gluconeogenesis- increasing the conversion of amino acids and glycerol into glucose in the liver
List 7 physiological changes that occur during the "fight or flight" response and describe the purpose of each
1. Heart rate increases- to pump more oxygenated blood around the body 2. Pupils dilate- to take in as much as possible for better vision 3. Arterioles in skin constrict- more blood to major muscle groups, brain, heat and muscles of ventilation 4. Blood glucose level increases- increase respiration to provide energy for muscle contraction 5. Smooth muscle of airways relaxes- to allow more oxygen into lungs 6. Non-essential systems shut down (like digestion)- to focus resources on emergency functions 7. Difficulty focusing on small tasks- brain solely focused only on where threat is coming from
Explain how temperature receptors in the hand generate an action potential in the sensory neurone to tell the body you are touching a hot object
1. Heat energy acts a stimulus 2. stimulus causes (voltage-gated) sodium ion channels to open 3. sodium ions diffuse into axon down electrochemical gradient 4. inside of axon becomes more positive/depolarises 5. an action potential is triggered along a sensory neurone to the CNS/Brain
Describe how bile is formed and how it travels to where it is stored
1. Hepatocytes secrete bile from the breakdown of the blood into spaces called the canaliculi 2. From these, the bile drains into the bile ductiles which take it to the Gall bladder
Describe how auxins, such as IAA, lead to growth in the lateral shoots
1. High concentration of auxins suppress the growth of lateral shoots- results in apical dominance 2. Growth in the main shoot is stimulated by the auxin produced at the tip so it grows quickly 3. The lateral shoots are inhibited by the hormone that moves back down the stem, so they do not grow very well 4. Further down the stem, the auxin concentration is lower so the lateral shoots grow more strongly 5. If the apical shoot is removed, the auxin-producing cells are removed and so there is no auxin and the lateral shoots grow faster 6. If auxin is applied artificially to the cut apical shoot, apical dominance is reasserted and lateral shoot growth is supressed
Summarise how ATP can be produced by chemiosmosis.
1. High energy electrons move form one carrier to another and this releases energy 2. This energy is used to pump protons across a membrane down a concentration gradient from the intermembrane space to the matrix therefore producing a proton gradient 3. The proton gradient is maintained as a result of the impermeability of the membrane to hydrogen ions 4. The only way the protons can move back through the membrane down their concentration gradient is through hydrophillic membrane channels linked to the enzyme ATP synthase (catalyses the formation of ATP) 5. The flow of protons through theses channels provides the energy used to synthesise ATP.
Describe the effect of solvent (e.g. ethanol) concentration on the permeability of cell membranes.
1. Higher solvent concentration- more permeable 2. The non-polar alcohol molecules can enter the cell membrane and the presence of these molecules between the phospholipids disrupts the membrane. 3. When the membrane is disrupted it becomes more fluid and permeable.
Describe the effect of changing temperature on the permeability of cell membranes.
1. Higher temp- more permeable 2. Phospholipids have more kinetic energy and will move more- making membrane more fluid and lose its structure- this increases the permeability of the membrane making it easier for particles to cross. 3. If temp continues to increase the cell will break down completely. 4. Channel and carrier proteins will be denatured at higher temps- as they denature membrane permeability will be affected.
Describe how hormonal communication occurs
1. Hormones are secretes into the blood when a gland is stimulated 2. Once secreted, the hormones are transported in the blood plasma all over the body 3. The hormones diffuse out of the blood and bind to specific receptors for the hormone, found on the membranes, or in the cytoplasm of cells in the target organs.- target cells 4. Once bound to their receptors the hormones stimulate the target cells to produce a response
Identify the host species of, and the type of pathogen causing, the following disease influenza
1. Host- animals including humans 2. Virus
Identify the host species of, and the type of pathogen causing, the following disease Tuberculosis
1. Host- animals- humans and cattle 2. Bacteria
Identify the host species of, and the type of pathogen causing, the following disease black sigatoka
1. Host- banana plants 2. Fungus
Identify the host species of, and the type of pathogen causing, the following disease ring worm
1. Host- cattle 2. Fungus
Identify the host species of, and the type of pathogen causing, the following disease bacterial meningitis
1. Host- humans 2. Bacteria
Identify the host species of, and the type of pathogen causing, the following disease athlete's foot
1. Host- humans 2. Fungus
Identify the host species of, and the type of pathogen causing, the following disease HIV/ AIDS
1. Host- humans 2. Virus
Identify the host species of, and the type of pathogen causing, the following disease potato blight
1. Host- potatoes 2. protoctist
Identify the host species of, and the type of pathogen causing, the following disease ring rot
1. Host- potatoes/ tomatoes 2. Pathogen- bacterium
Explain how apoptosis is controlled
1. Hox genes regulate apoptosis and mitosis 2. During development, genes that control apoptosis and genes that control mitosis are switched on or off in appropriate cells 3. This means some cells die, whilst some new cells are produced and the correct body plan develops
List 4 benefits of using insulin produced from genetically engineered bacteria rather than from pigs to treat diabetes. For each benefit explain why the benefit exists
1. Human insulin is produced in a pure form- means it is less likely to cause allergic reactions 2. Insulin can be produced in much higher quantities 3. Production costs are must cheaper 4. People's concern over using animal products in humans, which may be religious or ethical, are overcome
Describe two examples of plants using pheromones to defend themselves
1. If a maple tree is attacked by insects, it releases pheromones which is absorbed by leaves on other branches. These leaves then make chemicals such as callose to help protect them if they are attacked. Leaves on nearby trrs also prepare for attack in response to these chemical signals 2. Some evidence that plants communicate by chemicals produced in the root systems and one plant can 'tell' a neighbour if it is under water stress
Describe how plants respond to prevent freezing
1. If cells freeze, their membranes are disrupted and they will die 2. The cytoplasm of the plant cells and the sap of in the vacuoles contain solutes which lower the freezing point. 3. Some plants produce sugars, polysaccharides, amino acids and even proteins which act as antifreeze to prevent the cytoplasm from freezing or protect the cells from damage even if they do freeze 4. Most species only produce chemicals which make them hardy and frost resistant during the winter months 5. It appears that different genes are suppressed and activated in response to a sustained fall in temperatures along with the reduction in day length, effectively preparing the plants to withstand frosty conditions.
Explain how graphs of the rate of photosynthesis under different environmental conditions can show what is limiting the rate of photosynthesis under a particular set of conditions.
1. If there are different varying conditions and separate lines on the graph which plateaued out at different points, look at what is the difference between where it has plateaued, and that is the limiting factor for the line which plateaued earlier.
Explain the importance of stem cells and why their activity must be carefully controlled.
1. If they don't divide fast enough then tissues are not efficiently replaced- leading to ageing. 2. If there is uncontrolled division the they form masses of cells- tumours- lead to cancer
Explain how natural selection has resulted in the change in frequency of dark and pale moths in populations of the peppered moth (Biston bettularia) near industrial towns and cities over time.
1. In industrial revolution trees became darker and so the dark moths were better adapted, so more survived etc. frequency of the dark allele increased 2. Now trees are lighter the frequency of the pale allele in the moth gene pool has increased
Explain how a Pacinian corpuscle converts mechanical pressure into a nerve impulse.
1. In its normal state (resting state) the stretch-mediated sodium ion channels in the sensory neurone's membranes are too narrow to allow sodium ions to pass through them 2. Pacinian corpuscle has a resting potential 3. When pressure is applied to the Pacinian corpuscle, the corpuscle changes shape, this causes the membrane surrounding its neurone to stretch 4. When the membrane stretches, the sodium ion channels present widen. Sodium can now diffuse into the neurone 5. The influx of positive sodium ions changes the potential of the membrane- becomes depolarised. This results in a generator potential 6. In turn, the generator potential creates an action potential (a nerve impulse) that passes along the sensory neurone 7. The action potential will then be transmitted along neurones to the CNS
Describe the mechanism for geotropism
1. In normal conditions, plants always receive a unilateral gravitational stimulus- gravity always act downwards 2. The response of plants to gravity can be seen in the laboratory using seedlings placed on their sides either in all-around light or in the dark 3. Shoots are usually negatively geotropic and roots are positively geotropic 4. This adaptation ensure that the roots grow down into the soil and the shoots grow up to the light 5. Geotropism are also known as gravitropisms.
Describe how sweating can be increased
1. In some mammals- humans and horses- there are sweat glands all over the body 2. As sweat evaporates from the surface of the skin, heat is lost, cooling the blood below the surface- latent heat of vapourisation 3. In some animals the sweat glands are restricted to the less hairy areas of the body such as paws- these animals often open their mouths and pant when they get hot- losing heat as it evaporates
Describe how terpenoids help protect plants from herbivory
1. Large group of compounds produced by plants which often form essential oils but also often act as toxins to insects and fungi that might attack the plant 2. Pyrethrin acts as an insect neurotoxin interfering with the nervous system 3. Citronella is an insect repellent produced by lemon grass
Describe the structure of haemoglobin.
1. Large, globular, conjugated protein made up of four polypeptide chains 2. Each chain contains an iron-containing haem prosthetic group
State the role of cholesterol in the membrane.
1. Regulates the fluidity of membranes. 2. They are positioned between phospholipids in a membrane bilayer, with hydrophillic end interacting with the heads and the hydrophobic end interacting with the tails, pulling them together.
Describe which side of the brain controls which side of the body
1. In the base of the brain, impulses from each side of the body cross 2. Therefore the left hemisphere receives impulses from the right-hand side of the body and the right hemisphere receives impulses from the left-hand side of the body
Describe the role of the proximal convoluted tubule
1. In the proximal convoluted tubule all of the glucose, amino acids, vitamins, and hormones are moved from the filtrate back into the blood by active transport 2. Around 85% of the sodium chloride and water is reabsorbed as well 3. The sodium ions are moved by active transport while the chloride ions and water follow passively down the concentration gradients 4. Once the substances have been removed from the nephron, they diffuse into the extensive capillary network which surrounds the tubules down steep concentration gradients 5. These are maintained by the constant flow of blood through the capillaries 6. The filtrate reaching the loop of Henle at the end of the proximal convoluted tubule is isotonic with the tissue fluid surrounding the tubule and isotonic with the blood
State 4 features of efficient exchange surfaces. For each feature explain how it increases efficiency of the exchange surface.
1. Increased SA- Provides area needed exchange, overcoming limitations SA:Vol ratio. e.g root hairs, villi 2. Thin layers- shorter distances for substances to diffuse- faster and more efficient e.g. alveoli, villi 3. Good blood supply- steeper conc gradient= faster diffusion. e.g alveoli, gills, villi 4. Ventilation to maintain conc gradient- faster diffusion e.g gills where flow of water carrying dissolved gases, alveoli
Draw a flow chart to show the effect of exercise on cardiac output
1. Increased muscular/metabolic activity 2. More carbon dioxide produced by tissues from increased respiration 3. Blood pH is lowered 4. Centre in medulla oblongata that speeds up heart rate, increases frequency of impulses to SAN via the sympathetic nervous system 5. SAN increases heart rate 6. Increased blood flow removes carbon dioxide faster 7. Carbon dioxide levels return to normal
What features should you be able to identify from a photomicrograph of skeletal muscle
1. Individual muscle fibres- long and thin multinucleated fibres that are crossed with a regular pattern of fine red and white lines 2. The highly structured arrangement of sarcomeres which as appear dark and light bands 3. Streaks of connective adipose tissue 4. Capillaries running in between the fibres
Describe how Ciliated epithelium are specialised for their function
1. Made of ciliated epithelial cells 2. Have hair like structures- cilia- which move in rhythmic manner 3. Line the trachea- cause mucus to be swept away from the lungs 4. Goblet cells are present- release mucus to trap unwanted particles present in the air and stops them reaching the lungs
Explain the sliding filament hypothesis of muscle contraction.
1. Initiation -Tropomyosin molecule prevents myosin head from attaching to the binding site on the actin molecule -Ca2+ ions bind to troponin causing it to change shape. -This pulls on the tropomyosin moving it away from the actin-myosin binding sites on the actin filament 2. Attach -Myosin heads now attaches to teh bidning stie of the actin filament forming a cross-bridge 3. Bend - The myosin head bends/flexes, pulling the acting filament along the myosin- power stroke - The molecule of ADP bound to the myosin head is released 4. Release - An ATP molecule can now bind to the myosin head. - This causes the head to released from the myosin binding site on actin, breaking the cross-bridge 5. Straighten - The calcium ions present in the sarcoplasm also activate the ATPase activity hydrolysing ATP releasing energy - This energy is used to return the myosin head to its original position 6. The myosin head can now return to its original position and reattaches to another actin-myosin binding site further along the actin filament and the cycle is repeated 7. During the period of stimulation many actin-myosin bridges form and break rapidly, pulling the actin filament along. This shortens the sarcomere and causes muscle to contract.
List 6 different types of plant chemical defences, and for each describe their role and give examples.
1. Insect repellants- pine resin, citronella 2. Insecticides- pyrethrins act as insect neurotoxins, caffeine- toxic to insects 3. Antibacterial compounds including antibodies- phenols- antiseptics made in many different plants 4. Antifungal compounds- phenols, saponins- interfere with fungal cell membranes 5. Anti-oomycetes- glucanases enzymes 6. General toxins- cyanide- toxic to most living things
List the functions of triglycerides (5 functions)
1. Insulation- slow conductors or heat so stored beneath skin of endotherms. maintain constant body temp- important in aquatic animals. Electrical insulation round nerves. 2. store of energy- produce 2x energy of carbs. Insoluble so don't affect water potential 3. protections for delicate organs- fat is stored around the organs like the kidney 4. buoyancy- less dense than water so insulated aquatic animals are buoyant (floats) - aids breathing 5. water source- by hydrolysis can provide metabolic water which desert animals use
Draw a flow chart showing the negative feedback system that controls blood sugar level
1. Insulin and glucagon are antagonistic hormones, that is, they work against each other 2. The system of maintaining blood glucose concentration is said to be self-regulating, as it is the level of glucose in the blood that determines the quantity of insulin and glucagon that is released 3. Blood glucose concentration is not constant, but fluctuates around a set point as the result of negative feedback 4. In times of stress adrenaline is released by the body, which raises the blood glucose concentration to allow more respiration to occur
Explain why ATP is a better, immediate source of energy for metabolic reactions than glucose
1. Inter-conversion of ATP and ADP is happening constantly in all living cells, meaning cells do not need a large store of ATP 2. Small- moves easily into and out of cells 3. Water soluble- energy requiring processes happen in aqueous environments 4. Contain bonds between phosphates with intermediate energy; large enough to be useful for cellular reactions but not so large that energy would be wasted as heat 5. Releases energy in small quantities- suitable to most cellular needs so that energy is not wasted as heat 6. Easily regenerated
Outline how an endotherm regulates its internal temperature.
1. Internal exothermic metabolic activities to keep them warm, and energy requiring physiological responses to help cool them down 2. They have passive ways to reduce energy demand on their bodies 3. Have similar behavioural responses as ectotherms- basking in sun, wallowing in water etc 4. Some become dormant through the coldest weather (hibernation) or through the hottest weather (aestivation) 5. Humans- clothes, houses which are heated 6. Physiological adaptation- peripheral temperature receptors, thermoregulatory centres of the hypothalamus, skin and muscles
Describe the structure and function mRNA
1. Is a single polynucleotide made in the nucleus during transcription. 2. mRNA carries the genetic code from DNA in the nucleus to the cytoplasm where it is used to make a protein during translation. 3. 3 groups of three adjacent bases are usually called codons.
Describe the process of peritoneal dialysis
1. Is done inside the body- it makes use of the natural dialysis membranes formed by the lining of the abdomen- the peritoneum 2. It is usually done at home and the patient can carry on with their normal life while it takes place 3. The dialysis fluid is introduced into the abdomen using a catheter 4. It is left for several hours for dialysis to take place across the peritoneal membranes, so that urea and excess mineral ions pass out of the blood capillaries, into the tissue fluid and out across the peritoneal membrane into the dialysis fluid 5. The fluid is then drained off and discarded, leaving the blood balanced again and the urea and excess minerals removed
Define the terms "precision"
1. Is the closeness of agreement between independent measurements obtained under the same conditions. 2. It depends only on the distribution of random errors and does not relate to the true value.
Draw a diagram of a pancreas section, label it and annotate with the functions of the structures labelled
1. Islets of langerhans a) lightly stained b) large and sperical clusters c) endocrine pancreas d) produce and secrete hormones 2. Pancreatic acini a) darker stained b) small, berry-like clusters c) exocrine pancreas d) produce and secrete digestive enzymes
Describe how scientists could have tested the idea that pax6 plays a role in eye development in all three species
1. Isolate (Pax6) gene from one species 2. detail e.g., PCR, restriction enzymes 3. test in different tissue/species (example of positive result e.g., eyes develop on legs) 4. switch gene off early in development and eyes will not develop 5. DNA sequencing and compare genes from different species
Describe and explain the possible effects of a substitution mutation.
1. It changes the codon so if the new codon codes for a different amino acid this will leads to change in proteins 2. But it may not as it is degenerate
Label and annotate a photomicrograph of liver tissue at low and high power to show key histological features
1. Low power- Central vein is big white circle type thing - Sinusoids are white lines in the pink - The cells are pink parts with nuclei in 2. High power- Can see red blood cells in white sinusoids - Kupffer cells can be seen around the edge of sinusoids - Hepatocytes are big pink areas- can see nucleus and little dots which are mitochondria
Draw, label and annotate a diagram to show the arrangement of neurones in the "knee jerk" reflex arc and the actions that occur in the stimulus-response pathway
1. It is a spinal reflex- the neural circuit only goes up to the spinal cord, not the brain 2. When the leg is tapped just below the kneecap, it stretches the patellar tendon and acts as a stimulus 3. This stimulus initiates a reflex arc that causes the extensor muscle on top of the thigh to contract 4. At the same time, a relay neurone inhibits the motor neurone of the flexor muscle, causing it to relax 5. This contraction, coordinated with the relaxation of the antagonistic flexor hamstring muscle, causes the leg to kick
Describe how blood pressure / hydrostatic pressure varies across the circulatory system.
1. It is higher near arteries and next in capillaries next to arterioles 2. Lower near venules
Describe the structure of the cerebrum
1. It is highly convoluted which increases its surface area considerably and therefore it capacity for complex activity 2. It is split into right and left hemispheres which control one half of the body 3. The outer layer of the cerebral hemispheres is known as the cerebral cortex 4. Six areas- frontal lobe, parietal lobe, occipital lobe, cerebellum, medulla oblongata, temporal lobe
Define the term "water potential", state the symbol for water potential, state the water potential of pure water and explain why water potential cannot have a positive value. (F)
1. It is the measure of the quantity of water compared to solutes measured as the pressure created by water molecules (kPa) 2. The likelihood of water molecules to diffuse into or out of a solution 3. Water potential of pure water- 0 5. You can't have a positive water potential as the highest water potential is water and that's 0 so nothing can be more than that.
Describe the location of the liver in mammals and draw and label a diagram to show the blood vessels going to and from the liver
1. It lies just below the diaphragm and is made up of several lobes 2. Oxygenated blood goes to the liver via the hepatic artery (branched off from the aorta) 3. Deoxygenated blood is removed from the liver via the hepatic vein (which joins to the inferior vena cava) 4. The liver is also supplied with blood by the hepatic portal vein. This carries blood loaded with the products of digestion straight from the intestines to the liver
Describe importance in converting the CO2 to HCO3-
1. It maintains a steep concentration gradient for carbon dioxide to diffuse from the respiring tissues into the erythrocytes. 2. When blood reaches the lung tissue where there is a relatively low level of CO2 the reverse reaction takes place- producing CO2 and water 3. Hydrogen carbonate ions diffuse into the erythrocytes and react with the hydrogen ions to form more carbonic acid. 4. This is broken down by carbonic anhydrase releasing free CO2 which diffuses into the lungs.
Describe what a calorimeter does
1. It measures the absorbance- the more concentrated the colour of the solution, the higher the absorbance is
What are the implications of haemodialysis for the patient
1. It takes about 8 hours and has to be repeated regularly 2. Have to remain attached to a machine several times a week for many hours 3. They also need to manage their diets carefully. eating relatively little protein and salt and monitoring their fluid intake to keep their blood chemistry 4. Takes place in hospital generally
Explain the "survival value" of the blinking reflex
1. It this reflex is present, it indicated that the lower brain stem is functioning. 2. This is used as part of an assessment to determine whether a patient is brain dead 3. Protects retina and lens from damage
Describe how vaccination results in artificial active immunity.
1. It triggers the primary immune response by the foreign antigens and your body produces antibodies and memory cells 2. If you come into contact with a live pathogen, the secondary immune response is triggered and you destroy the pathogen rapidly
Outline how the sequence of bases in DNA can code for the primary structure of a polypeptide chain.
1. It's the order of nucleotide bases in a gene that determines the order of amino acids in a particular protein. 2. Each amino acid is coded for by a sequence of three bases (triplet) in a gene. 3. Different sequences of bases code for different amino acids.
Amylase
1. Its a globular protein 2. Its an enzyme which catalyses the breakdown of starch 3. It is made of a single chain of amino acid 4. its secondary structure contains both alpha-helix and beta-pleated sheet sections 5.Most enzymes are globular proteins
Haemoglobin
1. Its a globular protein and has quaternary structure 2. Carries blood around the body in red blood cells 3. It has a prosthetic group attached to it so is a conjugated protein. 4. Each of the 4 polypeptide chains in haemoglobin has a prosthetic group called haem 5. A haem group contains iron which oxygen binds to
Inuslin
1. Its a globular protein with a Quaternary structure 2. Its a hormone secreted by the pancreas to help regulate blood glucose level . 3. Soluble- it can be transported in the blood to the tissues where it acts 4. It consists of 2 polypeptide chains which are held together by disulfide bonds. 5. when in pancreas 6 of these molecules binds together to form a large globular structure
Show the chemical symbol and biological processes potassium ions are responsible for
1. K+ 2. Important for generating nerve impulses, for muscle contraction and for regulating fluid balance in the body 3. Activates essential enzymes needed for photosynthesis in plant cells- stomatal opening
Describe ways in which the kidneys can be damaged
1. Kidney infections (where the structure of podocytes and tubules may become damaged and destroyed) 2. Raised blood pressure (damage the structure of epithelial cells and basement membrane of the Bowman's capsule) 3. Genetic conditions (e.g polycystic kidney disease where the healthy kidney tissue is replaced by fluid-filled cysts or damaged by pressure from cysts)
Describe the structure of the nasal cavity
1. Large SA with good blood supply- warms air to body temp 2. Hairy lining- secretes mucus to trap dust and bacteria protecting delicate lung tissue from infection 3. Moist surfaces- increase humidity of incoming air, reducing evaporation from exchange surfaces
List 3 examples of disaccharides and for each state which monosaccharides they are composed of. (F)
1. Sucrose- alpha-glucose and Fructose 2. Lactose- Alpha- glucose and galactose 3. Maltose- Alpha glucose and Alpha-glucose
Explain why myofibrils have a striped appearance
1. Light bands- these areas appear light as they are the region where the actin and myosin filaments do not overlap. Also known as isotonic bands or I-bands 2. Dark bands- these areas appear dark because of the presence of thick myosin filaments. The edges are particularly dark as the myosin is overlapped with actin. Also known as anisotropic bands or A-bands 3. Z-line- this is a line found at the centre of each light band. The distance between adjacent z-lines is called a sarcomere 4. H-zone- this is a lighter coloured region in the centre of each dark band. Only myosin filaments are present at this point. When the muscle contracts the H-zone decreases. see p371
State 5 environmental factors that can affect the rate of transpiration and for each explain how they have their effect.
1. Light intensity- Lighter the faster- stomata open when it gets light (photosynthesis), increasing the rate of water vapour diffusing out and therefore increasing the evaporation from the surfaces of the leaves 2. Temperature- higher the faster- increases the kinetic energy of the water molecules ad therefore increases the rate of evaporation. It also increases the concentration of water vapour that the external air can hold before becomes saturated- decrease water potential 3. Humidity- lower humidity, faster transpiration- if air around plant is dry, it increases the water potential gradient between the leaf ad air 4. Wind- Windier the faster- blows water molecules away from the around the stomata, increasing the water potential gradient 5. Soil-water availability- if dry soil the plant will be under water stress and rate will decreases
Describe how light intensity affects the rate of photosynthesis
1. Light is needed for an energy source for the light dependent reaction. 2. As light intensity increases, ATP and reduced NADP are produced at a higher rate 3. If there isn't any- then no ATP or reduced NADP will be made so the Light independent reaction can't take place.
Name the two main stages of photosynthesis and state where each occurs in a chloroplast.
1. Light-dependent stage- in the photosystems in the thylakoid membrane 2. Light-independent stage- stroma
Explain how to use a stage micrometer to work out the distance represented by the small divisions in an eyepiece graticule under 3 different objective lenses.
1. Line up the eye piece graticule with the stage micrometer (the fixed scale on the slide). 2. get the scale on the micrometer slide in focus. 3. align the micrometer scale with the scale in the eyepiece take a reading from both of them. 4. See what the equivalent value of stag units is to eyepiece units. 5. work out the stage units in mm by dividing by ten ( 1 stage unit = 0.1 mm) 6. Divide the stage units in mm by the number of eyepiece units. 7. then put this in the right unit (micrometre) by multiplying by 1000 (magnification factor)
Describe the differences in the respiratory quotients
1. Lipids contain a greater proportion of carbon-hydrogen bonds than carbohydrates which is why they produce so much more ATP in respiration 2. Due to the greater number of carbon-hydrogen bonds, lipids require relatively more oxygen to break them down and release relatively less carbon dioxide 3. This results in RQs of less than 1 for lipids 4. The structure of amino acids leads to RQs somewhere between carbohydrates and lipids 5. It takes 6 oxygen molecules to completely respire 1 molecule of glucose and this results in the production of 6 molecules of carbon dioxide, resulting in an RQ value of 1.0
Why do the properties of water make it such an important component of blood?
1. Liquid so transport medium 2. polar solvent and (many) biological molecules (e.g., enzymes, glucose) are polar and ions are charged 4. coolant so (relatively) resistant to temperature change
Describe the role of B memory cells
1. Live a long time as part of the immunological memory 2. Programmed to remember a specific antigen and enable the body to make a very rapid response when a pathogen carrying that antigen is encountered again
Draw and label an ECG with the names of the sections.
1. Look at a graph 2. The P wave- small one at start- is caused by contraction of the atria 3. QRS complex- main peak of heartbeat with the dips either sided- is caused by contraction of the ventricles 4. T wave- smaller wave at the end- due to relaxation of the ventricles 5. Height of the wave- indicated how much electrical charge is passing through the heart- bigger means stronger contraction
Describe 6 effects of kidney failure
1. Loss of electrolyte balance (if the kidney's fail, the body cannot excrete sodium, potassium and chloride ions. This causes osmotic imbalances in the tissues and eventual death) 2. Build-up of toxic urea in the blood (if the kidneys fail, the body cannot get rid of urea and it can poison the cells) 3. High blood pressure (the kidneys play an important role in controlling the blood pressure by maintaining the water balance of the blood. If the kidneys fail, the blood pressure increases and this can cause a range of health problems and strokes) 4. Weakened bones (calcium/ phosphorus balance in the blood is lost) 5. Pain and stiffness in joints as abnormal proteins build up in the blood 6. Anaemia (the kidneys are involved in the production of a hormone called erythropoietin that stimulates the formation of red blood cells . When the kidneys fail it can reduce the production of red blood cells causing tiredness and lethargy)
Describe how auxins, such as IAA, lead to growth in the root growth
1. Low concentrations of auxins promote root growth 2. Up to a given concentration, the more auxin that reaches the roots, the more they grow 3. Auxin is produced by the root tips and auxin also reaches the roots in low concentrations from the growing shoots 4. If the apical shoot is removed, then the amount of auxin reaching the roots is greatly reduced and root growth slows and stops 5. Replacing the auxin artificially at the cut apical shoot restores the growth of the roots 6. High auxins concentrations inhibit root growth.
Give two examples of vaccination programmes that aim to provide herd immunity.
1. MMR- given to children at a year old and just before they start school 2. Meningitis C - given to babies at 3 months and boosters are given at 1 year and to teens.
Describe how captive breeding programmes try to maintain (or increase) genetic diversity.
1. Maintaining genetic diversity within a programme can be difficult- only a small number of breeding partners are available, so problems with inbreeding can occur 2. An international catalogue is maintained, detailing genealogical data on individuals 3. Mating can thus be arranged to ensure the genetic diversity is maximised 4. Techniques such as artificial insemination, embryo transfer and long-term cryogenic storage of embryos allow new genetic lines to be introduced without having to transport adults to new locations and do not require the animals' cooperation
Describe how to carry out an experiment to investigate the effects of solutions of different water potential on plant and animal cells.
1. Make up NaCl solutions of different concentrations e.g 0.2, 0.4 etc and pour an equal volume into separate beakers 2. Take de-shelled eggs and carefully pat them with absorbent paper to remove excess moisture. 3. Use a mass balance to weigh each egg, record mass in a table 4. place each egg in a different beaker and leave for same amount of time. 5. remove eggs, dry them and weigh again and use results to calculate percentage change in mass- plot graph Repeat- with potato cylinders of equal size in sucrose solutions
List some common anatomical adaptations of animals that live in cold climates
1. Many reduce SA:V ratio to reduce cooling (small ears) 2. Thick layer of insulating fat underneath the skin (blubber in seals and whales) 3. Some hibernate (build up fat stores)
Draw and label diagrams of a relay neurone
1. Many short axons and dendrons 2. Cell body in the middle as a circle surrounded by small dendrons and axons 3. Dendrites branch from the axons and dendrons 4. Myelinated
Describe the processes involved in the inflammatory response and explain their value for protection against pathogens.
1. Mast cells are activated in damaged tissue and release chemicals called histamines and cytokines 2. Histamines make the blood vessels dilate, causing localised heat and redness. The raise temperature helps prevent pathogens reproducing 3. Histamines make the blood vessel walls more leaky so blood plasma is forced out, once forced out of the blood it is know as tissue fluid. Tissue fluid causes swelling and pain 4. Cytokines attract white blood cells to the site which dispose of the pathogens by phagocytosis
Describe how the rate of anaerobic respiration and aerobic respiration can be measured in yeast.
1. Measure volume of CO2 released 2. Have glucose in a sealed flask to ensure anaerobic conditions 3. As the yeast respires Carbon dioxide is released increasing the volume of gas in the flask. Measure the volume of gas produced using a gas syringe 4. Calculate the volume of CO2 produced in a given time 5. You can use a data logger as well with a CO2 sensor as this can also measure changes in temperature which can be used to measure heat energy lost 6. Insert the CO2 sensor into a flask containing glucose and yeast and cover the solution with a layer of paraffin.
Write an equation that provides a measure of genetic diversity.
1. Measuring polymorphism. Genes that aren't polymorphic are said to be monomorphic- a single allele exists for this gene- ensures basic structure of individuals within a species remains consistent 2. Proportion of polymorphic gene loci= Number of polymorphic gene loci/ total number of loci
Describe two adaptations that insects with very high energy demands have to increase the efficiency of their gas exchange system.
1. Mechanical ventilation of the tracheal system- air is actively pumped into the system by muscular pumping movements of the thorax and/or abdomen. These movements change the volume of the body- changes the pressure in tracheae and tracheoles- air is drawn into or forced out of them as pressure changes. 2. Collabsible enlarged tracheae or air sacs which act as resevoirs- these are used to increase the amount of air moved through the gas exchange system- usually they are inflated or deflated by the ventilating movements of the thorax and abdomen.
Describe 4 ways in which biodiversity may be affected by climate change.
1. Melting of the ice polar caps can lead to the extinction of the few plants and animal species living in these regions 2. Rising sea levels from melting ice caps and thermal expansion of oceans could flood low-lying lands, reducing the available habitats. Saltwater would flow further up rivers reducing the habitats of freshwater plants and animals. 3. Higher temps and less rainfall would result in some plant species failing to survive leading to drought-resistant plants becoming more dominant. This would lead to loss of animal species dependent on them as a food source 4. Insect life cycles and populations will change as they adapt to climate change. As insects are key pollinators of many plants this could affect the lives of the plants it leaves behind causing extinction. As tropical insects spreads so do tropical diseases.
State 5 roles of membranes within cells and at the surface of cells.
1. Membranes around organelles divide the cells into different compartments- acting as a barrier between the organelle and the cytoplasm 2. Membranes can form vesicles to transport substances between different areas of the cell. 3. Membranes within cells are also partially permeable so they can control which substances enter and the leave the organelle. 4. Membranes within organelles act as barriers between the membrane contents and the rest of the organelle 5. Membranes within cells can be the site of chemical reactions. the membranes of some organelles are folded, increasing their surface area and making chemical reactions more efficient.
Explain, in a paragraph and with a diagram, how substances can move across a membrane by facilitated diffusion
1. Membranes contain channel proteins through which polar molecules and ions can pass. 2. Membranes with protein channels are selectively permeable as most protein channels are specific to one molecule or ion. 3. It can also involve carrier proteins which change shape when a specific molecule binds to it. 4. Doesn't require energy and is down the concentration gradient 5. Has same factors affecting it as simple diffusion. but also affected by the number of channel proteins present.
Explain how temperature affects the rate of an enzyme-controlled reaction.
1. More heat means more kinetic energy, so molecules move faster. 2. Means substrate molecules more likely to collide with active sites of enzymes. 3. The energy of these collisions also increases- so each collision is more likely to result in a reaction. 4. The rate increases until the enzyme reaches its optimum temperature, where the rate is at it's fastest. 5. Past this temperature the enzyme's molecules vibrate more, and these vibrations break some of the bonds that hold the enzyme in shape. 6. The active site changes shape and the enzyme and substrate no longer fit together. Enzyme- denatured
What is the role of the pancreas as an exocrine gland
1. Most of pancreas is made up of exocrine glandular tissue 2. This tissue is responsible for producing digestive enzymes and an alkaline fluid known as pancreatic juice. 3. The enzymes and juice are secreted into ducts which eventually lead to the pancreatic duct 4. From here they are released into the duodenum, the top part of the small intestines 5. The pancreas produces three important types of digestive enzymes: amylases, protesases and lipases
Describe the mechanism of inspiration in bony fish.
1. Mouth opens and floor of buccal cavity is lowered 2. Expansion of buccal cavity increases the volume and reduces pressure causing water to enter via the mouth (buccal cavity pressure pump) 3. At the same time the opercular valve is shut and the opercular cavity containing the gill expands 4. This lowers the pressure in the opercular cavity containing the gills. 5. The floor of the buccal cavity starts to move up, increasing the pressure there so water moves from the buccal cavity over the gills to the opercular cavity
What happens when thin, impermeable barrier of mica is put in the illuminated side of the shoot and it is exposed to unilateral light
1. Movement of chemical down shaded side and bends towards the light 2. Mica on the illuminated side of the shoot allows the hormone to pass only down the shaded side where it increases growth and causes bending
What happens when the tip is removed and a gelatin block inserted and tip replaced in the shoot and it is exposed to unilateral light
1. Movement of chemical down shaded side and it bends towards the light 2. As gelatin allows chemicals to pass through it, but not electrical messages, the bending which occurs must be due to a chemical passing from the tip
Describe the apoplast pathway of water movement.
1. Movement of water through the apoplast- cell walls and intercellular spaces 2. Water fills spaces between the loose, open network of fibres in the cellulose cell wall- by diffusion 3. As water molecules move into the xylem, ore water molecules are pulled through the apoplast behind hem due to cohesive forces 4. This pull from the water into the xylem and up the plant along with cohesive forces causes a tension- meaning there is a continuous flow of water through he open structure of the cellulose cell wall- little or no resistance
Describe the characteristics of Animalia
1. Multicellular 2. A nucleus and other membrane-bound organelles (no cell walls) 3. No chloroplasts 4. Move with the aid of cilia, flagella, or contractile proteins, sometimes in the form of muscular organs 5. Nutrients are acquired by ingestion- they are heterotrophic feeders 6. Food stored as glycogen
Describe the characteristics of Plantae
1. Multicellular 2. A nucleus and other membrane-bound organelles including chloroplasts, and a cell wall mainly composed of cellulose 3. All contain chlorophyll 4. Most do not move, although gametes of some plants move using cilia or flagella 5. Nutrients are acquired by photosynthesis- they are autotrophic feeders- organisms that make their own food 6. Store food as starch
Describe the events that occur at a neuromuscular junction in order to cause (and then stop) muscle contraction
1. Muscle contraction is triggered when an action potential arrives at a neuromuscular junction- point where a motor neurone and a skeletal muscle fibre meet 2. When an action potential reaches the neuromuscular junction, it stimulates calcium ion channels to open 3. Calcium ions then diffuse from the synapse into the synaptic knob, where they cause synaptic vesicles to fuse with the presynaptic membrane 4. Acetylcholine is released into the synaptic cleft by exocytosis and diffuses across the synapse 5. It binds to receptors on the postsynaptic membrane (sarcolemma), opening sodium ion channels and resulting in depolarisation 6. Acetylcholine is then broken down by acetylcholinesterase into choline and ethanoic acid 7. This prevents the muscle being overstimulated 8. Choline and ethanoic acid diffuse back into the neurone, where they are recombined into acetylcholine, using energy provided by mitochondria.
Draw, label and annotate a diagram of a muscle fibre to show the components of the cell and their function
1. Muscle fibres are enclosed within a plasma membrane known as the sarcolemma 2. The muscle fibres contain a number of nuclei and are much longer than normal cells, as they are formed as a result of many individual embryonic muscle cells fusing together 3. This makes the muscle stronger, as the junction between adjacent cells would act as a point of weakness 4. The shared cytoplasm within a muscle fibre is known as sarcoplasm 5. Parts of the sarcolemma folds inwards (known as transverse or t-tubules) to help spread electrical impulses throughout the whole sarcoplasm. THis ensures the whole of the fibre receives the impulse to contract at the same time 6. Muscle fibres have lots of mitochondria to provide ATP that is needed for muscle contraction 7. They also have modified version of the endoplasmic reticulum, known as the sarcoplasmic reticulum. This extends throughout the muscle fibre and contains calcium ions required for muscle contraction.
Describe the evidence supporting a link between gibberellins and seed germination.
1. Mutant varieties of seeds have been bred which lack the gene that enables them to make gibberellins. These seeds do not germinate. If gibberellins are applied to the seeds externally, they then germinate normally 2. If gibberellin biosynthesis inhibitors are applied to seeds, they do not germinate as they cannot make the gibberellins needed for them to break dormancy. If the inhibition is removed, or gibberellins are applied, the seeds germinate.
Name and describe the two ways in which the genetic biodiversity of a population can be increased.
1. Mutation- in the DNA of an organism creating a new allele 2. Interbreeding between different populations. When an individual migrates from one population and breeds with a member of another populations alleles are transferred between the two populations - gene flow
Describe and explain how an action potential is transmitted along a myelinated axon
1. Myelinated axons transfer electrical impulses much faster than non-myelinated axons 2. This is because depolarisation of the axon membrane can only occur at the node of Ranvier where no myelin is present 3. Here the sodium ions can pass through the protein channels in the membrane. Longer localised circuits therefore arise between adjacent nodes 4. The action potential then jumps from one node to another in a process known as saltatory conduction 5. This is much faster than the wave of depolarisation along the whole length of the axon membrane 6. Every time channels open and ions move it takes time, so reducing the number of places where this happens speeds up the action potential transmission 7. Long-term saltatory conduction is also more energy efficient. Repolarisation uses ATP in the sodium-potassium pump, so by reducing the amount of repolarisation needed, saltatory conduction makes the conduction makes the conduction of impulses.
Describe the structure of myosin
1. Myosin filaments have globular heads that are hinged which allows them to move back and forwards 2. On the head is a binding site for each of actin and ATP 3. The tails of several hundred myosin molecules are aligned together to form the myosin filament.
Describe the similarities and differences between FAD and NAD.
1. NAD takes part in all stages of cellular respiration but FAD only accepts hydrogen in the Krebs cycle 2. NAD accepts one hydrogen and FAD accepts two 3. Reduced NAD is oxidised at the start of the electron transport chain releasing protons and electrons while reduced FAD is oxidised further along the chain 4. Reduced NAD results in the synthesis of three ATP molecules but reduced FAD results in the synthesis of only two ATP molecules.
Name 3 coenzymes involved in respiration and describe the function of each
1. NAD- delivers electrons to electron transport chain 2. FAD- delivers electrons to electron transport chain 3. Acetyl CoA- delivers acetyl group to Krebs cycle
Show the chemical symbol and biological processes ammonium ions are responsible for
1. NH4+ 2. Production of nitrate ions by bacteria
Show the chemical symbol and biological processes nitrate ions are responsible for
1. NO3- 2. Absorbed from the soil by plants and is an important source of nitrogen
Show the chemical symbol and biological processes sodium ions are responsible for
1. Na+ 2. Important for generating nerve impulses, for muscle contraction and for regulating fluid balance in the body
Explain why plants need to respond to their environment
1. Need to respond to abiotic stresses 2. Animals wanting to eat them 3. Pathogens
Give two examples of systems whose purpose is cell signalling
1. Nervous system 2. Endocrine system
State the two systems which coordinate mammalian responses to stimuli
1. Nervous system 2. Endocrine system
State the 4 main categories of tissues in animals.
1. Nervous tissue- adapted to support transmission of electrical impulses 2. Epithelial tissue- adapted to cover body surfaces, internal and external 3. Muscle tissue- adapted to contract 4. Connective tissue- adapted either to hold other tissues together or as a transport medium.
Outline the process of cell signalling in these two systems.
1. Nervous- transfer signals locally for example between neurones at synapses. Signal used is a neurotransmitter 2. Endocrine- Transfer signals over large distances, using hormones. For example, the cells of the pituitary gland secrete ADH which acts on kidney
Describe how a mutation can have a neutral effect, a harmful effect or a beneficial effect, and give an example of each
1. Neutral- no effect on the phenotype of an organism because normally functioning proteins are still synthesised 2. Harmful- the phenotype of an organism is affected in a negative way because proteins are no longer synthesised or proteins synthesised are no longer functional.- interfere with essential processes 3. Beneficial- proteins is synthesised so it has new and useful characteristics in the phenotype.- e.g immunity to HIV from proteins in cell surface membrane
What happens when a light proof cover is placed over intact tip of shoot and it is exposed to unilateral light
1. No response 2. The light stimulus must be detected by the tip
What happens when a plant shoot with the top removed is exposed to unilateral light
1. No response 2. The tip must either detect the stimulus or produce the messenger (or both) as its removal prevents any response
State which types of molecule can move across a membrane by simple diffusion.
1. Non-polar molecules like oxygen diffuse through freely down a concentration gradient. 2. The hydrophobic interior of the membrane repels ions so they can't pass through easily. 3. Polar molecules like water can diffuse through membranes but only at a very slow rate. Small polar ones pass through easier
Describe how fever is initiated in response to invasion by pathogens and explain its value for protection against pathogens.
1. Normal body temp is maintained by thte hypothalamus in your Brain 2. When a pathogen invades your body, cytokines stimulate your hypothalamus to reset the thermostat as your temp goes up 3. Most pathogens reproduce est at 37 degrees or lower. So higher temps inhibit pathogen reproduction. 4. The specific immune system works faster at higher temps
Describe the structure and function of the lymphatic system.
1. Not all of the fluid re-enters the capillaries at the vein end - some excess tissue fluid is left over. 2. This extra fluid gets returned to the blood through the lymphatic system 3. The smallest lymph vessels are called the lymph capillaries 4. Excess tissue fluid passes into the lymph vessels- one inside it's called lymph 5. Valves in the lymph vessels stop the lymph going backwards 6. Lymph gradually moves towards the main lymph vessels in the thorax, where it's returned to the blood- near the heart.
Protein production
1. Nucleus- Transcription- DNA is converted to mRNA and is sent out of the nucleus into cytoplasm via the nuclear pores 2. Ribosomes on RER- mRNA attaches to the ribosomes and proteins are made (translation) 3. RER- proteins are folded and processed in the RER. then they are transported from the RER to the cis face of the Golgi apparatus in vesicles 4. Golgi apparatus- proteins may undergo further processing (e.g sugar chains are trimmed or more are added) 5. Proteins leave the Golgi apparatus from the transface in the secretory vesicles 6. Secretory take the finished proteins to the plasma membrane where they undergo exocytosis and leave the cell
Name the types of organisms that are obligate anaerobes, facultative anaerobes and obligate aerobes
1. Obligate anaerobe- almost all are prokaryotes although there are some fungi as well 2. Facultative anaerobes- yeast 3 Obligate aerobes- mammals, the individual cells of some organisms can be described as facultative anaerobes (e.g. muscle cells in mammals.
Describe the function of xylem parenchyma
1. Packs around the xylem vessels storing food and containing tanin deposits- bitter chemicals that protects plant tissue from attack by herbivores
Describe the role of acetylcholinesterase and explain how acetylcholine is recycled
1. Once a neurotransmitter has triggered an action potential in the postsynaptic neurone, it is important that it is removed so the stimulus is not maintained, and so another stimulus can arrive and affect the synapse 2. Any neurotransmitter left in the synaptic cleft is removed 3. Acetylcholine is broken down by enzymes which also releases them from the receptors on the postsynaptic membrane 4. The products are taken back into the presynaptic knob where ATP released by mitochondria is used to recombine choline and ethanoic acid into acetylcholine 5. This is stored in vesicles for future use 6. Sodium ion channels close in the absence of acetylcholine in the receptor site 7. Removing the transmitter from the synaptic cleft prevents the response from happening again and allows the neurotransmitter to be recycled
Describe the main features and function of adrenaline
1. One of its main function during flight or fight is to trigger liver cells to undergo glycogenolysis so that glucose is released into the bloodstream. This allows respiration to increase so more energy is available for muscle contraction 2. It is hydrophilic so cannot pass through cell membranes 3. It binds with receptors on the surface of liver cell membrane and triggers a chain reaction inside the cell
Name and describe the 3 main techniques of non-random sampling
1. Opportunistic (This is the weakest form of sampling, as it may not be representative of the population - uses organisms that are conveniently available) 2. Stratified (Some populations can be divided into a number of strata based on a particular characteristic.- a random sample is then taken form each of theses strata proportional to its size) 3. Systematic (Different areas within an overall habitat are identified which are then sampled separately)
Describe the steps in the process of adaptations evolving by natural selection
1. Organisms within a species show variation in their characteristics that are caused by genetic variation 2. Organisms whose characteristics are best adapted to a selection pressure- predation, competition- have an increased chance of surviving and successfully reproducing 3. Successful organisms pass the allele encoding the advantageous characteristic onto their offspring 4. This process is repeated for every generation. Over time, the proportion of individuals with the advantageous adaptation increases. There fore the frequency of the allele that codes for this increases in the population's gene pool 5. Over a very long periods of time this process can lead to the evolution of new species
Draw a diagram to show how urea is produced from excess amino acids via the ornithine cycle
1. Ornithine + NH3 + CO2 → H2O + Citruline 2. Citruline + NH3 → H2O + Arginine 3. Arginine + H2O → Urea + ornithine Overall: 2NH3 + CO2 → H2O + Urea
How does the negative feedback loop respond when water is in short supply
1. Osmoreceptors in the hypothalamus of the brain are sensitive to the concentration of inorganic ions in the blood and are linked to the release of ADH 2. The concentration of inorganic ions in the blood rises and the water potential of the blood and tissue fluid becomes more negative 3. This is detected by osmoreceptors in the hypothalamus 4. They send nerve impulses to the posterior pituitary which in turn releases stored ADH into the blood 5. The ADH is picked up by receptors in the cells of the collecting duct and increases the permeability of the tubules to water 6. Water leaves the filtrate in the tubules and passes into the blood in the surrounding capillary network 7. A small volume of concentrated urine is produced
Draw, label and annotate a diagram of a mitochondrion
1. Outer mitochondrial membrane- separates the contents of the mitochondrion from the rest of the cell, creating a cellular compartment with ideal conditions 2. Inner mitochondrial membrane- contains electron transport chains and ATP synthase 3. Cristae- are projections of the inner membrane which increase the surface area available for oxidative phosphorylation 4. Matrix- contains enzymes for the Krebs Cycle and the link reaction, also contains mitochondrial DNA 5. Inter-membrane space- Protons are pumped into this space by the electron chain. The space is small so the concentration builds up quickly.
Describe the process of the link reaction
1. Oxidative Decarboxylation 2. Step that links anaerobic glycolysis in the cytoplasm to aerobic steps if respiration in the rest of the mitochondria 3. Pyruvate enters the mitochondrial matrix by active transport via specific carrier proteins. 4. Pyruvate then undergoes oxidative decarboxylation- CO2 is removed (decarboxylation) along with hydrogen( oxidation). 5. The hydrogen atoms removed are accepted by NAD to form reduced NAD. 6. The resulting two-carbon acetyl group is bound by co-enzyme A forming acetylcoenzyme (acetyl CoA). 7. Acetyl CoA delivers the acetyl groups to the next stage of aerobic respiration- Krebs cycle 8. Reduced NAD is used in oxidative phosphorylation to synthesis ATP 9. Acetyl groups are now all that is left of the original glucose molecules- CO2 will diffuse away and be removed as metabolic waste or may be used as raw material in photosynthesis.
Explain how hydrogen bonds form
1. Oxygen and hydrogen share electrons unequally when they bond 2. Oxygen, has a greater share/ is more negative 3. Hydrogen, has a smaller share/is more positive 4. The more negative oxygen atom is attracted to the more positive hydrogen atom
Draw a table to compare the structure and function of the sympathetic and parasympathetic nervous systems.
1. PNS is most active in sleep and relaxation, SNS is most active in times of stress 2. SNS- neurones of a pathway are linked at a ganglion just outside the spinal cord (long post-ganglionic neurones, short pre-ganglionic neurones). PNS- neurones of a pathway are linked at a ganglion within the target tissue (long pre-ganglionic neurones and short post-ganglionic neurones) 3. SNS- neurotransmitter is noradrenaline, PNS- uses acetylcholine
Describe the stages in phagocytosis.
1. Pathogens produce chemicals that attract phagocytes 2. Phagocytes recognise non-human proteins on the pathogen, this is a response not to a specific type of pathogen, but simply a cell or organism that is non-self 3. The phagocyte engulfs the pathogen and encloses it in a vesicle called a phagosome 4. The phagosome combines with a lysosome to form a phagolysosome 5. Enzymes from the lysosome digest and destroy the pathogen 6. Digested pathogen absorbed by the phagocyte-antigens combine with the MHC in the cytoplasm 7. MHC/antigen complex is displayed on phagocyte membrane making an antigen presenting cell
Define Type 1 diabetes
1. Patients with type 1 diabetes are unable to produce insulin 2. The B-cells in the islets of Langerhans do not produce insulin 3. The cause of type 1 diabetes is not known, so at the moment, the disease cannot be prevented or cured, but it is possible to treat the symptoms 4. Evidence suggests that it arises as a result of an autoimmune response where the body's own immune system attacks the B-cells.
Define type 2 diabetes
1. Patients with type 2 diabetes cannot effectively use insulin and control their blood-sugar levels 2. This is either because the person's β cells do not produce enough insulin or the person's body cells do not respond properly to insulin 3. This is often because the glycoprotein insulin receptor on the cell membrane does not work properly 4. The cells lose their responsiveness to insulin and therefore do not take up enough glucose leaving it in the bloodstream.
State 3 pieces of equipment used to measure the functioning of the lungs. For each outline how they work.
1. Peak flow meter- simple- measures the rate at which air can be expelled from the lung. 2. Vitalographs- more sophisticated versions of PFM- tests the amount of air they breathe out and how quickly this is done- forced expiatory volume in 1 second. 3. Spirometer- can be used to measure several different aspects of lung volume
Describe 6 examples of common medicinal drugs derived from living organisms.
1. Penicillin- from mould on melons- antibiotic 2. Docetaxel- derived from yew trees- treatment for breast cancer 3. Aspirin- based on compounds from sallow bark- painkiller, anti-coagulent, anti-pyretic, anti-inglammatory 4. Prialt- derived from venom of a cone snail- pain killing drug 5. Vancomycin- derived from soil fungus- one of most powerful anti-biotics 6. Digoxin- based on digitoxin originally extracted from foxgloves- powerful heart drug used for atrial fibrillation and heart faliure
Describe the role of cytokines in the non-specific defences.
1. Phagocytes that have engulfed a pathogen produce chemicals called cytokines 2 These act as cell-signalling molecules, informing other phagocytes that the body is under attack and stimulating them to move to the site of infection or inflammation 3. They can also increase the body temp and stimulate the specific immune system
Describe the steps of the process of glycolysis.
1. Phosphorylation- the first step of glycolysis requires two molecules of ATP. Two phosphates released from the two ATP molecules, are attached to a glucose molecules forming hexose bisphosphate 2. Lysis- this destabilises the molecule causing it to split into two triose phosphate molecules 3. Phosphorylation- another phosphate group is added to each triose phosphate forming two triose bi-phosphate molecules. These phosphate groups come from free inorganic phosphate ions present in the cytoplasm 4. Dehydrogenation and formation of ATP- the two triose bisphosphate molecules are then oxidised by the removal of hydrogen atoms to form two pyruvate molecules. NAD co-enzymes accept the removed hydrogens-they are reduced, forming two reduced NAD molecules 5. At the same time 4 ATP molecules are produced.
How are plants sensitive to daylight
1. Photoperiodism- sensitive to lack of light in their environment 2. Many different plants responses are affected by the photoperiod including the breaking of dormancy of the leaf buds so they open up, the timing of flowering in a plant and when tubers are formed in preparation for overwintering 3. The sensitivity to day length results from a light-sensitive pigment called phytochrome 4. This exists in two forms Pr and Pfr. 5. Each absorbs a different type of light and the ration of Pr to Pfr changes depending on the levels of light.
State the 3 types of mutagen and give an example of each
1. Physical - ionising radiation such as x-rays - break one or both DNA strands 2. Chemical - Deaminating agents - chemically alter bases in DNA 3. Biological agents a) Alkylating agents - methyl or ethyl groups are attached to bases - results in incorrect base pairing b) Base analogs - incorporated into DNA in place of the usual bases in replication c) Viruses - viral DNA may insert itself into a genome
List 8 endocrine glands, the hormone they secrete and the general role of each hormone.
1. Pituitary gland (In brain)- growth hormone, anti-diuretic hormone and gonadotrophins (control development of ovaries and testes 2. Pineal gland (brain)- melatonin (affects reproductive development and daily cycles) 3. Thyroid gland (neck)- thyroxine (controls rate of metabolism and rate that glucose is used up in respiration and promotes growth) 4. Adrenal gland (above kidney)- adrenaline (increases heart and breathing rate and raises blood-sugar level) 5. Testis- produces testosterone (controls sperm production and secondary sexual characteristics) 6. Thymus (chest)- thymosin (promotes production and maturation of white blood cells) 7. Pancreas (stomach area)- insulin (converts excess glucose into glycogen in the liver) and glucagon (converts glycogen back to glucose in the liver) 8. Ovary- oestrogen (controls ovulation and secondary sexual characteristics),and progesterone, (which controls ovulation and secondary sexual characteristics and prepares the uterus lining for receiving an embryo)
Describe the test for Reducing sugars
1. Place a sample in a boiling tube and add equal volumes of Benedict's reagent 2. Heat the mixture gently 3. Blue>green>yellow>orange>brick red precipitates depending on their concentration 4. A qualitative test
List the different types of response they have with examples of each.
1. Plant defences against herbivory (chemical or physical) 2. The control of growth (phototropism, geotropism, apical dominance and stem elongation 3. The triggering of specific events (leaf loss, seed germination, stomatal closure, preventing freezing)
Describe the role of botanic gardens in maintaining biodiversity.
1. Plant species can be grown successfully as they are actively managed to provide them with the best resources to grow. 2. Such as the provision of soil nutrients, sufficient watering and the removal or prevention of pests 3. But many wild relatives of selectively bred crop species are under-represented amongst the conserved species. 4. These wild species are a potential source of genes, conferring resistance to diseases, pests and parasites
Describe and explain 6 factors that affect the transmission of communicable diseases in plants.
1. Planting a varieties of crops that are susceptible to disease 2. Over-crowding increases the likelihood of contact 3. poor mineral nutrition reduces resistance of plants 4. damp, warm conditions increase the survival and spread of pathogens and spores 5. climate change- increased rainfall and wind promote the spread of diseases- allow animal vectors to spread to new areas. Drier conditions may reduce the spread of disease
Explain why a plant might close its stomata and describe this process including the role of plant hormones
1. Plants can respond to stress of heat and water availability, opening the stomata can cool the plant as water evaporates from the cells in the leaves in transpiration or to close the stomata to conserve water 2. Opening and closing od stomata in response to abiotic stresses is largely under control of the hormone ABA 3. The leaf cells appear to release ABA under abiotic stress, causing stomatal closure 4. Scientists think that the roots also provide an early warning of water stresses through ABA 5. e.g when the levels of soil water fall and transpiration is under threat, plant roots produce ABA which is transported to the leaves here it bind to receptors on the plasma membrane of the stomatal guard cells 6. ABA activates changes in ionic concentration of the guard cells, reducing the water potential and therefore the turgor of the cells 7. As a result of reduced turgor, the guard cells close the stomata and water loss by transpiration is greatly reduced.
Describe what happens when plants grow in the dark
1. Plants grow more rapidly in the dark 2. If a plant is in the dark the biological imperative is to grow upwards rapidly to reach the light ot be able to photosynthesise 3. The seedlings that break through the soil first will not have to compete with other seedlings for light 4. Evidence suggests that it is gibberellins that are responsible for the extreme elongation of the internodes when a plant is grown in the dark 5. Once a plant is exposed to the light, a slowing of upwards growth is valuable 6. Resources can be used for synthesising leaves, strengthening stems, and overall growth. Scientists have demonstrated that levels of gibberellin fall once the stem is exposed to light 7. The rapid upward growth which takes place in a plant grown in the dark is etiolation 8. Etiolated plants are thin and pale- little chlorophyll develops.
List the components of blood and describe their functions.
1. Plasma- yellow liquid- carries a variety of other components (dissolved glucose, amino acids, mineral ions, hormones) 2. Plasma also transports large plasma proteins- albumin, fibrinogen and globulins 3. Plasma also transports- red blood cells- carry oxygen and white blood cells and platelets
Describe 5 ways to sample animals.
1. Pooter (catch small insects by sucking on a mouthpiece, draws insects into the holding chamber via the inlet tube) 2. Sweep nets (catch insects in long grass) 3. Pitfall traps (catch small crawling invertebrates in a hole that is dug in the ground- deep enough so they can come out and is covered with a roof structure to stop drowning) 4. Tree beating (a large white cloth is stretched out under the tree, the tree is shaken or beaten to dislodge invertebrate) 5. Kick sampling (the river bank and bed is kicked for a period of time to disturb the substrate. The net is held downstream for a set period of time in order to capture any organisms released into the flowing water)
List 2 similarities and 2 differences between the structure of ATP and DNA and RNA nucleotides.
1. RNA and ATP both have a ribose sugar, but DNA had deoxyribose. 2. DNA and RNA both have 1 phosphate group, but ATP has 3. 3. They all have one base.
Define α-cell
1. Present in the islet of Langerhan 2. They produce and secrete glucagon 3. stained pink
State the condition in which insulin is released and from which cells, and describe how insulin has its effect on cells
1. Produce by the β-cells of the islets of Langerhans in the pancreas 2. If blood glucose concentration is too high β-cell detect this rise in blood glucose concentration and respond by secreting insulin directly into the blood stream 3. Virtually all body cells have insulin receptors on their cell surface membrane (except rbc) 4. When insulin binds to its glycoprotein receptor, it causes a change in the tertiary structure of the glucose transport protein channels 5. This causes the channels to open allowing more glucose to enter the cell 6. Insulin also activates enzymes within some cells to convert glucose to glycogen and fat
Describe the role of captive breeding programmes in maintaining biodiversity.
1. Produce offspring of species in a human-controlled environment (Often in zoos or aquatic centres) . Several species are now solely represented by animals in captivity 3. The aim is to create a stable, healthy population of a species and then gradually reintroduce the species back into its natural habitat 4. They provide the animals with shelter, and abundant supply of nutritious food, an absence of predators and veterinary treatment.
State the condition in which glucagon is released and from which cells, and describe how glucagon has its effect on cells.
1. Produced by the α-cells of the islets of Langerhans in the pancreas 2. If blood glucose concentration is too the low, the α-cells detect this fall in blood glucose concentration and respond by secreting glucagon directly into the bloodstream 3. Only cells in the body which have glucagon receptors are the liver cells and fat cells - theses are the only cells that can respond 4. As blood-glucose returns to normal, this is detected by α-cells, when it rises above a set level, the α-cells reduce their secretion of glucagon- negative feedback
Name the 5 kingdoms and give examples of the organisms they contain
1. Prokaryotae (bacteria) 2. Protoctista (the unicellular eukaryotes) Amoeba 3. Fungi (yeasts, moulds, mushroom) 4. Plantae (the plants) 5. Animalia (animals)
Describe how proteins are used in respiration.
1. Proteins first have to be hydrolysed to amino acids 2. Then the amino acids have to be deaminated (removal amine groups) before they enter the respiratory pathway usually via pyruvate 3. These steps require ATP reducing the net production of ATP 4. Proteins produce roughly the same amount of energy as carbs
Describe the role of marine conservation zones in maintaining biodiversity.
1. Purpose is to create areas of refuge withing which populations can build-up and repopulate adjacent areas. 2. Vital in preserving species-rich areas such as coral reefs which are being devastated by non-sustainable fishing methods. 3. Large areas of sea are required for marine reserve as the target species often move large distances or breed in geographically different areas.
Describe the process of lactate fermentation
1. Pyruvate can act as a hydrogen acceptor taking the hydrogen from the reduced NAD, catalysed by the enzyme lactate dehydrogenase. The pyruvate is converted to lactate (lactic acid) and NAD regenerated 2. This can be used to keep glycolysis going so a small quantity of ATP is still synthesised 3. In mammals in particular, anaerobic respiration in the muscles is often supported by ATP from aerobic respiration, which is still being produced as fast as oxygen can be delivered in other parts of the body 4. Lactic acid is converted back to glucose in the liver but oxygen is needed to complete this process. This is the reason for the oxygen debt and the need to breathe heavily after exercise.
Name the different types of cell found in blood and outline how to identify them on blood smear slides.
1. RBC- don't have nucleus 2. Neutrophil- nucleus looks like 3 interconnected blobs - multi-lobed and the cytoplasm is grainy 3. Lymphocyte- smaller than neutrophil and nucleus takes up most of the cell, so little cytoplasm to be seen 4. Monocyte- biggest wbc and is a type of phagocyte, it has a kidney-bean shaped nucleus and a non-grainy cytoplasm
What are the different types of symmetry in animal body shape
1. Radial symmetry - seen in diploblastic animals - no right or left sides only a top or bottom e.g. jellyfish 2. Bilateral symmetry - most animals - have both right and left sides and a head and a tail rather than just a top and bottom 3. Asymmetry - sponges - no lines of symmetry
Explain why a temperature probe linked to a data-logger may be advantageous over the use of a thermometer when investigating factors affecting the abundance and distribution of organisms in an area.
1. Rapid changes can be detected 2. Human error in taking a reading is reduced. 3. A high degree of precision can often be obtained. 4. Data can be stored and tracked on a computer
Define the term "respiratory quotient (RQ)" and write the equation for the respiratory quotient.
1. Ratio of carbon dioxide produce to oxygen used in respiration 2. RQ= CO2 produced / O2 consumed 3. It is measured using a respirometer
Properties unrelated to being a polar molecule
1. Reactivity 2. Transparency 3. Poor conductivity 4. low viscosity
Outline the steps in a stimulus-response pathway and identify the role of the sensory, relay, and motor neurones in this pathway.
1. Receptor- detects a stimulus and creates an action potential in the sensory neurone 2. Sensory neurone- carries impulse to spinal cord 3. Relay neurone- connects the sensory neurone to the motor neurone within the spinal cord or brain 4. Motor neurone- carries impulse to the effector to carry out the appropriate response
Describe 2 ways in which a plant cell can detect the presence of a pathogen.
1. Receptors in the cells respond to molecules from the pathogens or to chemicals produced when the plant cell wall is attacked. Or they might detect the breakdown products of the cell wall from digestion from the pathogen 2. This stimulates the release of signalling molecules that appear to switch on genes in the nucleus. 3. This in turn triggers cellular responses which include producing defensive chemicals, sending alarm signals to unaffected cells to trigger their defences and physically strengthening the cell walls.
Draw a table to compare the components of blood, tissue fluid and lymph.
1. Red blood cells- B - Too big to get through capillary walls into tissue fluid 2. White blood cells- B, Few in TF, L- Most are in lypmh system, only enter tissue fluid when there's infection 3. Platelets-B - Only present in tissue fluid if the capillaries are damaged 4. Proteins-B, few in TF, only antibodies in L- Most plasma proteins are too big to get through capillary walls 5. Water- B,TF,L- TF and L have higher water potential than blood 6. Dissolved solutes- B, TF, L - can move freely between them
Describe 4 ways in which deforestation affects biodiversity.
1. Reduces the number of trees 2. If only a specific type of tree is felled the species diversity is reduced 3. It reduces the number of animal species present in an area as it destroys their habitat, this in turn reduces or removes other animals food sources 4. Animals are forced to migrate to other areas to ensure their survival, this may result in the biodiversity of neighbouring areas increasing.
Define the term "compensation point" in relation to light intensity and describe how it can be determined for a particular photosynthetic organism.
1. Reducing light intensity will reduce the rate of the light-dependent stage of photosynthesis. This will reduce the quantity of ATP and reduced NADP produced. 2. ATP and reduced NADP are needed to convert GP to TP. 3. The concentration of GP will increase and concentration of TP will decrease. 4. As there will be less TP to regenerate RuBP, the concentration of RuBP will also decrease. 5. The reverse will happen when light intensity is increased. 6. Its a compromise because even if you increase light intensity there won't be enough of the CO2 so the Calvin cycle will be slow- CO2 concentration would also need to be increased
What causes the change in colour in Benedict's reagent when mixed with reducing sugars
1. Reducing sugars can donate electrons and reduce other molecules 2. Blue Cu2+ are reduced to brick red Cu+
Describe the characteristics of reflex actions and the survival value of them
1. Reflexes are essential for survivla as they avoid the body being harmed or reduce severity of any danger 2. Reflexes increase your chances of survival by: 1. Being involuntary responses- the decision-making regions of the brain are not involved, therefore the brain is able to deal with more complex responses. It prevents the brain from being overloaded with situations in which the response is always the same 2. Not having to be learnt- They are present at birth and therefore provide immediate protection 3. Extremely fast- The reflex arc is very short. It normally only involves one or two synapses, which are the slowest part of nervous transmission 4. Many reflexes are what we would consider everyday actions, such as those which keep us upright and those which control digestion
How is type 2 diabetes treated
1. Regulate persons carbohydrate intake through their diet and matching this to their exercise 2. Some cases this is not enough so drugs also have to be used 3. These drugs can be ones that stimulate insulin production, drugs that slow down the rate at which the body absorbs glucose from the intestine and ultimately even insulin injections
Describe 6 factors that may cause a decrease in genetic diversity.
1. Selective breeding (where a few individuals within a population are selected for their advantageous characteristics and bred) 2. Captive breeding programmes (a small number of captive individuals of a species are available for breeding in zoos and conservation centres) 3. Artificial cloning (asexual reproduction using cutting to clone a farmed plant) 4. Natural selection (Species evolve to contain the alleles which code for advantageous characteristics) 5. Genetic bottlenecks (where a few individuals within a populations survive an event or change thus reducing the gene pool) 6. Founder effect (a small number of individuals create a new colony geographically isolated from the original. The gene pool for this population is small) 7. Genetic drift (due to random nature of alleles being passed on from parents the frequency of occurrence of an allele will vary- some cases the existence of a particular allele can disappear from a population altogether)
Describe how Mimosa pudica folds in response to touch.
1. Sensitive plant Mimosa pudica is one of a small number of plants which move at a speed you can see 2. If the leaves are touched, they fold down and collapse 3. Scientists think this frightens off larger herbivores, and dislodges small insects which have landed on the leaves 4. The leaf falls in a few seconds, and recovers over 10-12 minutes as a result of potassium ion movement into specific cells, followed by osmotic water movement.
Describe the test for lipids
1. Shake the test substance with ethanol for about a minute 2. Then pour into water. 3. If lipid is present a white emulsion forms as a layer on top of the solution. 4. If no lipid present the solution will remain clear
Describe the structure of phloem and explain how it is adapted for its function.
1. Sieve tube elements which are made up of many cells joined end to end to form a long hollow structure 2. Unlike xylem tissue the phloem tubes are not lignified. 3. Between the cells there are sieve plates 4. The tonoplast, nucleus and other organelles breakdown- becomes a tube filled with phloem sap - mature phloem cells have no nucleus 5. Companion cells (maintain their nucleus and organelles) are linked to the sieve tube elements by plasmodesmata.- they are very active cells and act as life support system for sieve tube cells 6. Phloem tissue also contains supporting tissues including fibres and sclereids- cells with extremely thick cell walls
Explain 2 reasons why multicellular plants have to have transport systems.
1. Size- Some are very large so need effective transport system to move substances up and down from the tip of the roots to the stems and leaves 2. SA- Overall have relatively small SA:Vol ratio, despite large leaf SA- once trunks and stems and roots are taken into account- so can't rely on diffusion alone.
List the 3 types of muscle and state where they occur and their basic function
1. Skeletal muscle- make up the bulk of body muscle tissue. These are responsible for movement 2. Cardiac muscle- cardiac muscle cells are found only in the heart. These cells are myogenic, meaning they contract without the need for a nervous stimulus 3. Involuntary muscle (smooth muscle)- Found in many parts of the body e.g. walls of stomach and bladder. They are also found in the walls of blood vessels and the digestive tract where through peristalsis they move food along the gut
State 3 characteristics which are determined by a combination of environment and genetics
1. Skin colour 2. Height/weight 3. hair colour
State 4 barriers the human body has to minimise the entry of pathogens into our cells.
1. Skin- acts as physical barrier, but also produces sebum- an oily substance that inhibits the growth of pathogens 2. Mucous membranes- secrete sticky mucus- traps microorganisms and contains lysozymes which destroy bacterial and fungal cell walls- also contain phagocytes 3. Lysozymes in tears and urine 4. Acid in the stomach denatures proteins and kills pathogens
Describe one risk of using stem cells to treat Type 1 diabetes
1. Slight risk of rejection 2. Risk that stem cells transplanted into the body might induce the formation of tumours as a result of unlimited cell growth.
Explain the importance of the structure of ATP in active transport.
1. Small - moves easily in and out of and within cells 2. Water soluble - Energy-requiring processes happen in aqueous environments 3. Contain bonds between phosphates with immediate energy; large enough to be useful for cellular reactions but not so large that energy is wasted as heat 4. Releases energy in small quantities - quantities are suitable to most cellular needs so that energy is not wasted as heat 5. easily regenerated - can be recharged with energy
List 3 methods for transporting carbon dioxide in the blood.
1. Small amount is dissolved in plasma 2. medium amount is combined with amino groups in the polypeptide chains of haemoglobin to form carbaminohaemoglobin 3. Large amount is converted into carbonate ions in the cytoplasm of the red blood cells
Describe the function of androgens
1. Small amounts of male and female sex hormones are released 2. Small impact compared to main sex hormones but still important
Explain the role of sodium ions, potassium ions, organic anions, the sodium/potassium ion pump and potassium ion channels in establishing and maintaining the resting potential
1. Sodium ions are actively transported out of the axon whereas potassium ions are actively transported into the axon by a specific intrinsic protein known as the sodium potassium pump 2. However their movement is not equal. For every 3 sodium ions pumped out, two potassium ions are pumped in 3. As a result there are more sodium ions outside the membrane than inside the axon cytoplasm, whereas there are more potassium ions inside the cytoplasm than outside the axon 4. Therefore, the sodium ions diffuse back into the axon down its electrochemical gradient whereas potassium ions diffuse out of the axon 5. However, most gated sodium ion channels are closed preventing the movement of sodium ions, whereas many potassium ion channels are open, so the potassium ions can diffuse out of the axon 6. Therefore, there are more positively charged ions outside the axon than inside the cell 7. This creates the resting potential of -70mV
Describe the role of T regulator cells
1. Suppress the immune system acting to control and regulate it. 2. They stop the immune response once a pathogen has been eliminated and make sure the body recognises self antigens and does not set up an autoimmune response 3. Interleukins are important in this control
Describe 8 economic reasons for maintaining biodiversity.
1. Soil erosion and desertification may occur as a result of deforestation- reduce a country's ability to grow crops and feed its people which can lead to resource ad economic dependence on other nations 2. Non-sustainable removal of resources will eventually lead to the collapse of industry in an area. Once the raw material has been lost it is not economically viable to continue the industry. 3. Large-scale habitat and biodiversity losses mean that species with potential economic importance may become extinct before they are discovered. 4. Continuous monoculture results in soil depletion- a reduction in the diversity of soil nutrients. This makes the crop support weaker, increasing vulnerability to opportunistic insects, plant competitors and microorganisms. Farmer will become dependent on expensive pesticides, fertilisers etc. 5. High biodiversity provides protection against abiotic stress. When not maintained a change in conditions or a disease can destroy entire crops. 6. High bio diverse places can promote tourism in the region. 7. The greater the diversity of an ecosystem, the greater the potential for the manufacture of different products in the future. 8. Plant varieties are needed for cross-breeding which can lead to better characteristics such as disease resistance. Wild relatives of cultivated crop plants provide genetic material to aid the production of new varieties of crops.
Explain, in a paragraph and with a diagram, how substances can move into a cell by endocytosis
1. Some molecules are way too large (proteins, lipids, some carbs and some white blood cells like phagocytes ) to be taken into a cell by carrier proteins. 2. Instead a cell can surround a substance with a section of its plasma membrane. the membrane pinches off to form a vesicle inside the cell containing the ingested substance. 3. This uses ATP as energy
Describe the evidence for the role of active transport in moving water from root endodermis into the xylem.
1. Some poisons - cyanide- affect the mitochondria and prevent the production of ATP - if cyanide is applied to root cells so there is no energy supply, root pressure disappears 2. Root pressure increases with a rise in temperature and falls with a fall in temperature suggesting chemical reactions are involved 3. If levels of oxygen or respiratory substrates fall, root pressure falls 4. Xylem sap may exude from the cut end of stems at certain times
Explain, in a paragraph and with a diagram, how substances can move out of a cell by exocytosis
1. Some substances produced by the cell (hormones or digestive enzymes or lipids) need to be released from the cell. 2. Vesicles containing these substances pinch off from the sacs of the Golgi apparatus and move towards the plasma membrane. 3. The vesicles fuse with the plasma membrane and release their contents outside the cell. Uses ATP as energy
Explain why a greater genetic biodiversity increases a species chances of long term survival.
1. Species that contain greater genetic biodiversity are likely to be able to adapt to changes in their environment and hence are less likely to become extinct 2. This is because there are likely to be some organisms within the population that carry an advantageous allele, which enables them to survive in the altered conditions.
What does the photoreceptors
1. Stimulus- light 2. Example- cone cell (detects different light wavelengths) 3. Example of organ- eye
Explain how comparative biochemistry provides evidence for evolution
1. Study of similarities and differences in the proteins and other molecules that control life processes 2. These molecules change over time but some important ones are highly conserved among species 3. Slight changes that occur in these molecules can help identify evolutionary links 4. Two most common molecules studied are cytochrome c (proteins involved in respiration) and ribosomal RNA 5. Molecular sequence of a particular molecule is compared-look at order of DNA bases or order of amino acids 6. Neutral substitution is changes that do not affect a molecule's function, they occur at a fairly regular rate 7. The number of differences are plotted against the rate the molecule undergoes neutral base pair substitution 8. From this the point at which the two species last shared a common ancestor can be estimated.
Describe the symplast route for phloem loading and explain how it occurs.
1. Sucrose moves through the cytoplasm of mesophyll cells and on into the sieve tubes by diffusion through the plasmodesmata 2. This route is largely passive, 3. The sucrose ends up in the sieve elements and water follows by osmosis 4. This creates a pressure of water that moves the sucrose through the phloem by mass flow
Describe the apoplast route for phloem loading and explain how it occurs.
1. Sucrose travels through the cell walls and inter-cell spaces to the companion cells and sieve elements by diffusion down the concentration gradient, maintained by the removal of sucrose into the phloem vessels. 2. Companion cells use ATP to pump H+ ions out of the cell by active transport 3. This creates a concentration gradient 4. Facilitated diffusion of H+ ions in down the concentration gradient. 5. Sucrose moves in with the hydrogen ions by co-transport 6. This also results in water moving into the companions cell and sieve tube element by osmosis- high hydrostatic and turgor pressure in companion cells 7. Sucrose move into the sieve tube elements by diffusion through the plasmodesmata
Describe the fate of the hydrogen carbonate ions produced when carbonic acid dissociates into hydrogen ions and hydrogen carbonate ions, describe how this is linked to the "chloride shift" and explain its importance.
1. The HCO3- ions diffuse out of the red blood cells and are transported in the blood plasma. 2. To compensate for the loss of HCO3- ions chloride ions diffuse into the red blood cells- chloride shift and it prevents any change in pH that could affect the cells.
Explain the "survival value" of the knee jerk reflex
1. The absence of this reflex may indicate nervous problems and multiple oscillation of the leg may be a sign of a cerebellar disease 2. This reflex is used by the body to help maintain posture and balance, allowing you to remain balanced with little effort or conscious thought
Explain in detail how a motor neurone causes a postsynaptic neurone to depolarise
1. The action potential reaches the end of the pre-synaptic/motor neurone 2. depolarisation of the pre-synaptic membrane causes calcium ion channels to open 3. calcium ions diffuse into the presynaptic knob and synaptic vesicles fuse with the presynaptic membrane and release neurotransmitter / exocytosis takes place 4. neurotransmitter diffuses across the synaptic cleft /binds with receptor on the postsynaptic membrane 5. sodium ion channels open and sodium ions diffuse into the post-synaptic neurone 6. threshold potential reached / depolarisation triggers an action potential 7. muscle cell contracts
Describe the sequences of events that occur at a synapse that can result in an action potential being generated in the post-synaptic neurone
1. The action potential reaches the end of the presynaptic neurone 2. Depolarisation of the presynaptic membrane causes calcium ion channels to open 3. Calcium ions diffuse into the presynaptic knob 4. This causes synaptic vesicles containing neurotransmitters to fuse with the presynaptic membrane. Neurotransmitter is released into the synaptic cleft by exocytosis 5. Neurotransmitter diffuses across the synaptic cleft and binds with its specific receptor molecule on the postsynaptic membrane 6. This causes sodium ion channels to open 7. Sodium ions diffuse into the postsynaptic neurone 8. This triggers an action potential and the impulse is propagated along the postsynaptic neurone
State the main way (from the ways water can be gained by, or lost from, the body) the body can adjust its water balance.
1. The amount of water lost in the urine is controlled by ADH in a negative feedback system 2. ADH is produced by the hypothalamus and secreted into the posterior pituitary gland, where it is stored 3. ADH increases the permeability of the distal convoluted tubule, and the collecting duct to water
Describe and explain 4 ways in which antibodies defend the body.
1. The antibody of the antigen-antibody complex acts as an opsonin so the complex is easily engulfed and digested by phagocytes 2. Most pathogens can no longer effectively invade the host cells once they are part of an antigen-antibody complex. 3. Antibodies act as agglutinins causing pathogen carrying antigen-antibody complexes to clump together. This helps to prevent them form spreading through the body- makes it easier for phagocytes to engulf a number of pathogens at the same time 4. Antibodies act as anti-toxins, binding to the toxins produced by pathogens and making them harmless
Describe the process of vasoconstriction
1. The arterioles near the surface of the skin constrict 2. The arteriovenous shunt vessels dilate, so very little blood flows through the capillary networks close to the surface of the skin 3. The skin looks pale and very little radiation takes place 4. The warm blood is kept well below the surface
Describe the process of vasodilation
1. The arterioles near the surface of the skin dilate when the temperature rises 2. The vessels that provide a direct connection between the arterioles and venules constrict 3. This forces blood through the capillary networks close to the surface of the skin 4. The skin flushes, and cools as a result of increased radiation 5. If the skin pressed against cool surfaces then the cooling results from conduction
describe what would happen if a refractory period did not exist
1. The axon could be immediately depolarised after an action potential 2. therefore the action potential could travel backwards / in both directions / not reach target cell
Describe the basic model of phototropism
1. The basic model of the way plants respond to light as they grown was based on experiments where shoots were entirely in the dark or in full illumination- rarely case in real life 2. Phototropisms are the results of the movement of auxins across the shoot or root if it is exposed to light that is stronger on one side than the other 3. If plants are grown in bright all-round light in normal conditions of gravity they grow more or less straight upwards 4. In even but low light they grow straight upwards and faster and taller than in bright light 5. If plants are exposed to light that is brighter on one side or to unilateral light that only shines from one side, then the shoots of the plant will grow towards the light and the roots, if exposed, will grown away 6. Shoots are positively phototropic and roots are negatively phototropic.
Describe the role of cAMP in control of the lac operon
1. The binding of RNA polymerase still only results in a relatively slow rate of transcription that needs t be increased or up-regulated to produce the required quantity of enzymes to metabolise lactose efficiently 2. This is achieved by the binding of another protein, cAMP receptor protein (CRP)- only possible when CRP is bound to cAMP 3. The transport of glucose into an E.Coli cell decreases the levels of cAMP, reducing the transcription of the genes responsible for the metabolism of lactose 4. If both glucose and lactose are present then it will still be glucose that is metabolised.
What are the different stimuli for the different types of blinking reflex
1. The blinking reflex is an involuntary blinking of the eyelids 2. It occurs when the cornea is stimulated e.g by being touched. Its purpose is to keep the cornea safe from damage due to foreign bodies such as dust or flying insects entering the eye. -corneal reflex 3. It alsos occurs when loud sounds 4. It also occurs as a result of very bright light- optical reflex
What is the countercurrent exchange system in heamodialysis
1. The blood and the dialysis fluid flow in opposite directions to maintain a countercurrent exchange system 2. This maximises the exchange that takes place
Describe how transplantation can treat kidney failure
1. The blood vessels are joined and the ureter of the new kidney is inserted into the bladder 2. If transplant successful, the kidney will function for many years
Describe the process of deamination
1. The body cannot store either proteins or amino acids 2. Any excess ingested protein would be excreted and therefore wasted if it were not for hepatocytes 3. They deaminate the amino acids removing the amino group, and converting it first into ammonia which is very toxic and then into urea 4. Urea is toxic in high concentrations but not in concentrations normally found in the blood 5. Urea is excreted by the kidney 6. The remainder of the amino acid can then be fed into cellular respiration or converted into lipids for storage
Define the term "humoral immunity" and suggest what it is particularly effective against
1. The body responds to antigens found outside the cells- bacteria, fungi and to APCs. 2. The humoral immune system produces antibodies that are soluble in the blood and tissue fluid and are not attached to the cells.
Define the term "humoral immunity" and suggest what it is particularly effective against.
1. The body responds to antigens found outside the cells- bacteria, fungi and to APCs. 2. The humoral immune system produces antibodies that are soluble in the blood and tissue fluid and are not attached to the cells.
Describe what happens in prophase
1. The chromosomes condense getting shorter and fatter. 2. Tiny bundles of protein called centrioles start moving to opposite ends of the cell forming a network of proteins fibres across it called the spindle. 3. The nuclear envelope breaks down and chromosomes lie free in the cytoplasm
Describe what happens in metaphase
1. The chromosomes line up along the middle of the cell (metaphase plate) and become attached to the spindle by their centromere 2. At the checkpoint the cell checks that the chromosomes are attached to the spindle before mitosis can continue.
Describe what happens during the Prophase 2 stage of meiosis
1. The chromosomes which still consist of two chromatids condense and become visible. 2. The nuclear envelope breaks down and spindle formation begins.
Describe the roles of the collecting duct and explain how it can perform these roles
1. The collecting duct passes down the through the concentration tissue fluid of the renal medulla 2. This is the main site where the concentration and volume of the urine produced is determined 3. Water moves out of the collecting duct by diffusion down a concentration gradient as it passes through the renal medulla. As a result the urine becomes more concentrated 4. The level of sodium ions in the surrounding fluid increases through the medulla from the cortex to the pelvis 5. This means water can be removed from the collecting duct all the way along its length, producing very hypertonic urine when the body needs to conserve water 6. The permeability of the collecting duct to water is controlled by the of ADH, which determines how much or little water is reabsorbed
Define frame shift
1. The deletion or insertion of a nucleotide or nucleotides leads to a frame-shift mutation 2. It shifts the reading frame of the sequence of bases, it will change every successive codon from the point of mutation
State 5 reasons why most animals need specialised transport systems.
1. The demands of most multicellular animals are high- so diffusion over long distances is not enough to supply the quantities needed 2. The SA:Vol ratio gets smaller as the multicellular organisms get bigger 3. Molecules such as hormones or enzymes may be made in one place but needed in another 4. Food will be digested in one orgna system but needs to be transported in every cell to be used for respiration 5. Waste products of metabolism need to be removed from the cells and transported to excretory systems
Name the hormone tested for in pregnancy tests and state where it is produced and when it starts being produced
1. The human embryo implants in the uterus, around 6 days after conception 2. The site of the developing placenta then begins to produce a chemical called human chorionic gonadotrophin (hCG). Some of this hormone is found in the blood and the urine of the mother 3. Modern pregnancy tests still test for hCG in the urine, but they rely on monoclonal antibodies. Some are so sensitive that pregnancy can be detected within hours of implantation
Describe the what happens in the descending limb of the loop of Henle
1. The descending limb leads from the proximal convoluted tubule- region where water moves out of the filtrate down the concentration gradient 2. The upper part is impermeable to water and runs down into the medulla 3. The concentration of the sodium and chloride ions in the tissue fluid of the medulla is high as a result of the a lot being moving out of the ascending limb of the loop of Henle by active transport 4. The filtrate entering the descending limb of the loop of Henle is isotonic with the blood 5. As it travels down the limb, water passes out of the loop into the tissue fluid by osmosis down a concentration gradient 6. It then moves down a concentration gradient into the blood of the surrounding capillaries 7. The descending limb is not permeable to sodium and chloride ions, and no active transport takes place in the descending limb 8. The fluid that reaches the hairpin bend is very concentrated and hypertonic to the blood in the capillaries
Describe how animals can reduce the insulating effects of hair or feathers
1. The erector pili muscles in the skin relax as body temperature begins to increase 2. As a result the hair or feathers of an animal lie flat to the skin 3. This avoids trapping an insulating layer of air 4. It has little of effect in humans
Define the term "stress" in relation to homeostasis and describe the factors that may influence the rate of mitosis or apoptosis
1. The expression of regulatory genes can be influenced by the environment, internal and external Stress can be defined as the condition produced when the homeostatic balance within an organism is upset 2. An internal stimulus could be DNA damage - if detected during cell cycle this can result in the expression of genes which cause the cycle to be paused and can even trigger apoptosis 3. An external stimulus - lack of nutrient availability - could result in gene expression that prevents cells from undergoing mitosis. Attack by pathogen leads to apoptosis.
Describe the process of normal expiration linking the action of muscles, to the movement of structures, the change in pressure within the lungs and the direction of airflow.
1. The external intercostal an diaphragm muscles relax. 2. The ribcage moves downwards and inwards and the diaphragm becomes curved again. 3. The thorax volume decrease, causing air pressure to increase 4. Air is forced out of the lungs down the pressure gradient 5. Normal expiration is passive process 6. Alveoli- elastic recoil
Compare the composition of the blood in the capillaries and the ultrafiltrate in the Bowman's capsule
1. The filtrate which enters the capsule contains glucose, salt, urea and many other substances in the same concentrations as they are in the blood plasma 2. The process is so efficient that up to 20% of water and solutes are removed from the plasma as it passes through the glomerulus
Describe the what happens in the ascending limb of the loop of Henle
1. The first section of the ascending limb of the loop of Henle is very permeable to sodium and chloride ions and they move out of the concentrated solution by diffusion down a concentration gradient 2. In the second section of the ascending limb, sodium and chloride ions are actively pumped out into the medulla tissue fluid against a concentration gradient 3. This produces a very high sodium and chloride ion concentration in the medulla tissue 4. The ascending limb of the loop of Henle is impermeable to water, so water cannot follow the chloride and sodium ions down a concentration gradient 5. This means the fluid left in the ascending limb becomes increasingly dilute, while the tissue fluid of the medulla develops the very high concentration of ions that is essential for the kidney to produce the urine that is more concentrated than the blood 6. By the time the dilute fluid reaches the top of the ascending limb it is hypotonic to the blood again and it then enters the distal convoluted tubule and collecting duct
Define the term "compartmentalisation" and explain why compartmentalisation is useful to cells.
1. The formation of separate membrane-bound areas in a cell is called compartmentalisation. 2. It is vital to a cell as metabolism includes many different and often incompatible reactions. 3. Containing reactions in separate parts of the cell allows the specific conditions required for cellular reactions.
Design an experiment to investigate one factor affecting geotropism in shoots or roots.
1. The geotropic response can be investigated in shoots and roots using a rotating drum known as a clinostat 2. The plants can be grown on a slowly rotating clinostat (4 rotations per hour) so the gravitational stimulus is applied evenly to all sides of the plant- and the root and in the dark shoots grow straight 3. Alternatively, the seeds can be placed in petri dishes stuck to the wall of the lab, and the dishes rotated 90 degrees at intervals as the seedlings grow. A geotropic response in the roots can be seen within about two hours.
Explain how increasing the substrate concentration affects the initial rate of an enzyme-controlled reaction.
1. The higher the substrate concentration the higher the rate of reaction. 2. More substrate molecules mean a collision between substrate and enzyme is more likely, so more active sites will be occupied and more enzyme-substrate complexes will be formed. 3. This is only true up to a certain point. 4. After that there are so many substrate molecules that the enzymes have about as much as they can cope with- all the active sites are full. 5. So adding more makes no difference- enzyme concentration becomes the limiting factor.
Describe what happens during the Metaphase 1 stage of meiosis
1. The homologous pairs line up across the metaphase plate and attach to the spindle fibres by their centromeres. 2. The orientation of each homologous pair is random and independent of any other homologous pair- independent assortment which can result in many different combinations of alleles facing the poles.
Draw a flow chart to show how adrenaline has its effect on cells
1. The hormone fuses to the receptor site and in doing so activates an enzyme inside the membrane 1. When adrenaline binds to its receptor, the enzyme adenylyl cyclase is activated 2. Adenylyl cyclase triggers the conversion of ATP into cyclic adenosine mono-phosphate cAMP on the inner surface of the cell membrane in the cytoplasm 3. The increase in cAMP levels activates specific enzymes called protein kinases which phosphorylate and hence activate other enzymes. In this example enzymes are activated which trigger the conversion of glycogen and glucose
Explain why the second messenger system is said to have a "cascade effect", and explain the usefulness of this effect.
1. The hormone is known as the first messenger and cAMP the second messenger 2. One hormone molecule can cause many cAMP molecules to be formed 3. At each stage the number of molecules involved increases so the process is said to have a cascade effect
Describe the role of plant hormones in leaf loss in deciduous plants.
1. The lengthening of the dark period in winter triggers abscission 2. The falling light levels results in falling concentrations of auxin 3. The leaves respond to the falling auxin concentration by producing the gaseous plant hormone ethene 4. At the base of the leaf stalk is a region called the abscission zone, made up of two layers of cells sensitive to ethene 5. Ethene seems to initiate gene switching in these cells resulting in the production of new enzymes. These digest and weaken the cell walls in the outer layer of the abscission zone, known as the separation layer 6. The vascular bundles which carry materials into and out of the leaf are sealed off 7. At the same time fatty material is deposited in the cells on the stem side of the separation layer. This layer forms a protective scar when the leaf falls, preventing the entry of pathogens 8. Cells deep in the separation zone respond to hormonal cues by retaining water and swelling, putting more strain on the already weakened outer layer 9. Then further abiotic factors such as low temperatures or strong winds finish the process- the strain is too much and the leaf separates from the plant leaving a neat waterproof scar is left behind.
What measures can be taken to reduce the risk of kidney rejection
1. The match between the antigens of the donor and the recipient is made as close as possible 2. Recipient is given immunosuppresent drugs for the rest of their lives 3. But immunosuppresent drugs is that they prevent the patients from responding effectively to infectious diseases
State which part of the brain controls heart rate, and describe how is role of controlling heart rate is divided into two centres.
1. The medulla oblongata in the brain is responsible for controlling heart rate. 2. There are two centres within the medulla oblongata, linked to the sinoatrial node in the heart by motor neurons 3. One centre increases heart rate by sending impulses through the sympathetic nervous system, these impulses are transmitted by the accelerator nerve 4. One centre decreases heart rate by sending impulses through the parasympathetic nervous system, these impulses are transmitted by the vagus nerve
Describe what happens during the prophase 1 stage of meiosis
1. The nuclear envelope disintegrates, the nucleolus disappears and the spindle formation begins. 2. The chromosomes condense and homologous chromosomes pair up forming bivalents. 3. Chromosomes are large molecules of DNA and moving through them the cytoplasm as they are brought together results in the chromatids entangling- crossing over.
Describe what happens during the Telophase 1 stage of meiosis
1. The nuclear envelope forms around each group of chromosomes 2. Cytokenisis- the division of the cytoplasm occurs and two haploid daughter cells are produced
Describe the features of a gas exchange system that become apparent under microscopic examination that aren't easily seen when observing the whole organ system.
1. The part of the system which improves surface area e.g. lamellae in fish- because they are usually very small projections so can't be easily seen 2. You can't see short diffusion distance
Describe how the oncotic pressure and hydrostaic pressure in capillaries is produced.
1. The plasma proteins give blood in the capillaries a relatively high solute potential- low water potential- compared with the surrounding tissue fluid 2. As a result water has a tendency to move into the blood in the capillaries from the surrounding fluid by osmosis- oncotic pressure 3. However as water flows through the arterioles into the capillaries it is still under pressure from the surge of blood that occurs from the heart contraction- hydrostatic pressure 4. This is higher than the oncotic pressure- so water is squeezed out of capillaries by hydrostatic pressure- forms tissue fluid. 5. As the blood moves towards venous system the hydrostatic pressure falls, so now the oncotic pressure is stronger- water moves back into capillaries by osmosis.
Describe 3 aesthetic reasons for maintaining biodiversity.
1. The presence of different plants and animals in our environment enriches out lives- relax on beach or have a walk 2. The natural world provides inspiration for people such as writers and artists 3. Studies have shown that patients recover more rapidly from stress and injury when they are supported by plants and a relatively natural environment
Define qualitative test
1. The process of determining whether or not a particular chemical is present in a sample.
Describe the purpose of chromatography.
1. The purpose is to show the different photosynthetic pigments present in plant extract, by separating them out. 2. The pigments have different solubilities so move up the paper by the solvent at different rates and distances. 3. Moves up by capillary action. 4. Rf value means retardation factor 5. Rf= Distance moved by pigment/ Distance moved by solvent 6. The ratio will help you identity different pigments. 7. Least soluble will move least difference and so will have smallest rf value
Describe how glomerular filtration rate can be estimated and describe the precautions that need to be taken when interpreting the results
1. The rate of filtration is not measured directly 2. A blood test measure the levels of creatinine in the blood- creatinine is a breakdown product of muscles and gives an estimate eGFR 3. The units cm^3/min 4. If the levels of creatinine in the blood go up, it is a signal that the kidneys are not working properly 5. Factors need to be taken into account e.g GFR decreases with age and men normally have more muscle mass and so creatinine than women
Explain how the lac operon works when lactose is absent from the growth medium
1. The repressor protein is constantly being produced and binds to an area called the operator 2. The binding of this protein prevents RNA polymerase binding to DNA and beginning transcription - down regulation 3. The section of DNA that is the binding site for the RNA polymerase is called the promoter
Describe the general features of circulatory systems.
1. They have a liquid transport medium that circulates around the system 2. They have vessels that carry the transport medium 3. They have a pumping mechanism to move the fluid around the system.
Describe the process of photolysis and what the products of photolysis are used for.
1. There is an enzyme as part of PS2 which catalyses the breakdown of water. 2. Electrons released replace the electrons lost from the reaction centre of PS2 3. Oxygen gas is released as a by-product 4. The protons are released into lumen of the thylakoids, increasing the proton concentration across the membrane. 5. As they move back through the membrane down a concentration gradient through the ATP synthase to the stroma. 6. This catalyses the reaction to convert ADP and phosphate to ATP at the active site of the enzyme. 7. Once the hydrogen ion has returned to the stroma they combine with the NADP and an electron from PS1 to form reduced NADP. 8. This removed the hydrogen ions from the stroma so it helps to maintain the proton gradient across the thylakoid membranes.
Define axon
1. These are singular, elongated nerve fibres that transmit impulses away from the cell body 2. These fibres can be very long, e.g. those that transmit impulses from the tips of toes and fingers to the spinal cord 3. The fibre is cylindrical in shape consisting of a very narrow region of cytoplasm surrounded by a plasma membrane
Define the terms "fibrous protein".
1. They are an insoluble and rope shaped protein. 2. They are very strong and are structural proteins and are fairly unreactive. 3. They are formed from long insoluble molecules. this is due to the presence of a high proportion of amino acids with hydrophobic R-groups in their primary structure . 4. They contain a limited range of amino acids usually with small R-groups. 5. They aren't folded into complex 3D shapes like globular proteins
Describe the location of the kidneys in humans and draw and label a diagram to show the human urinary system
1. They are attached to the back of abdominal cavity 2. They are surrounded by a thick protective layer of fat and a layer of fibrous connective tissue 3. The kidneys are supplied with blood by the renal arteries that branch off from the abdominal aorta 4. Blood that has circulated through the kidneys is removed by the renal vein that drains into the inferior vena cava 5. From kidney the urine passes down the ureter into the bladder and out the urethra
Explain how the cells of the proximal convoluted tubule are adapted for their function
1. They are covered with microvilli, greatly increasing the surface area over which substances can be reabsorbed 2. They have many mitochondria to provide the ATP needed in active transport systems
Explain the role of the peripheral temperature receptors in thermoregulation.
1. They are in the skin 2. Detect changes in the surface temperature 3. The combination of the hypothalamus and peripheral temperature receptors gives the body great sensitivity and allows it to respond not only to actual changes in the temperature of the blood but to pre-empt possible problems that might result from
What do chemoreceptors detect and how does this affect heart rate
1. They are located in the aorta, carotid artery and the medulla 2. Chemoreceptors are sensitive to changes in the pH level of the blood 3. If the CO2 level in the blood increases, the pH of the blood decreases because carbonic acid formed when the CO2 interacts with water in the blood 4. If chemoreceptors detect a decrease in pH, a response is triggered to increase heart rate- blood therefore flows more quickly to the lungs so the CO2 can be exhaled 5. When the CO2 level in the blood decreases, the pH of the blood rises. This is detected by the chemoreceptor in the wall of the carotid arteries and the aorta 6. This results in a reduction in the frequency of the nerve impulses being sent to the medulla oblongata, which in turn reduces the frequency of impulses being sent to the SAN via the sympathetic nervous system and thus heart rate is back to normal
Define the term "personalised medicine", give an example of how treatment is being personalised, and suggest the value of personalising medicine to a person's genetic information.
1. They are medicines that are tailored to an individual's DNA- dependent upon the characteristics of the individual (size, age but particularly the individual's genomes) 2. The theory is that doctors will be able to predict how you will respond to different drugs and only prescribe the ones that will be most effective for you- avoid side effects.
Outline how plant hormones can be transported around plants and have their effect
1. They are released by cells 2. Travel through the plant by diffusion or active transport across and between cells and by mass flow in xylem or phloem 3. They then trigger a response in target cells or tissues.
Describe the role of Hox genes in controlling the body plan of animals
1. They are responsible for the correct positioning of body parts 2. In animals the Hox genes are found in gene clusters- mammals have 4 clusters on different chromosomes 3. The order in which the genes appear along the chromosomes is the order in which their effects are expressed in the organism 4. Humans have 39 Hox genes in total that are believed to have originated from one from one ancient homeobox gene
State 3 characteristics of sensory receptors and for each explain why they are important.
1. They are specific to a single type of stimulus- you don't a stimulus to trigger multiple receptors because the response may not be suitable for the stimulus 2. They act as a transducer- convert a stimulus into a nerve impulse- means the information can be passed through the nervous system to cause a response 3. Sensitive
Define the terms "globular protein"
1. They are spherical water-soluble proteins. 2. In globular proteins the hydrophillic R-groups on the amino acids tend to be pushed to the outside of the molecule. 3. This is caused by the hydrophobic and hydrophillic interactions in the protein's tertiary structure. 4. This makes globular proteins soluble so are easily transported in fluids.
Describe the role of opsonins in phagocytosis.
1. They bind to pathogens and tag them so they can be more easily recognised by phagocytes. 2. Phagocytes have receptors on their cell membranes that bud to common opsonins, and the phagocyte then engulfs the pathogen.
State 3 roles of synapses and for each describe the importance of this role to the nervous system
1. They ensure impulses are unidirectional 2. They can allow an impulse from one neurone to be transmitted to a number of neurones at multiple synapses. This results in a single stimulus creating a number of simultaneous responses 3. Alternatively, a number of neurones may feed in to the same synapse with a single postsynaptic neurone. This results in stimuli for different receptors interacting to produce a single response
Draw a table to show 10 adaptations xerophytes have for conserving, storing or accessing water and for each adaptation explain how it benefits the plant.
1. Thick waxy cuticle- minimise water loss 2. Sunken stomata- stomata located in pits, which reduce air movement, producing a micro-climate of humid air that reduces the water potential gradient 3. Reduced number of stomata- reduce water loss by transpiration but also reduce gas exchange capabilities 4. Reduced leaves- greatly reduced SA:Vol ratio minimising water loss by transpiration 5. Hairy leaves- like spines on cacti create a micro-climate of still, humid air, reducing the water potential gradient- some have micro-hairs in the sunken stomatal pits 6. Curled leaves- confines all the stomata within a micro-environment of still, humid air to reduce diffusion of water vapour form the stomata 7. Succulents- store water in specialised parenchyma tissue in their stems and roots- water is stored for droughts 8. Leaf loss- Some plants lose their leaves when water isn't available- palo verde loses all it's leaves in long, dry seasons and it's trunk and branches turn green and photosynthesise with minimal water loss 9. Root adaptations- long roots that can grow deep into the ground or a mass of widespread shallow roots that can absorb any available water before it evaporates. 10. Avoiding the problems- many lose their leaves and become dormant or die completely leaving seeds behind to germinate. How well did you know this?
Describe the role of the cerebellum in coordinated muscular movement.
1. This area of the brain is concerned with the control of muscular movement, body posture and balance- it does not initiate movement but coordinates it 2. If this area of the brain is damaged, a person suffers from jerky, uncoordinated movement 3. The cerebellum receives information from the organs of balance in the ears and information about the tone of muscles and tendons 4. It then relays this information to the areas of the cerebral cortex that are involved in motor control
Define autonomic nervous system
1. This works constantly 2. It is under subconscious control and is used when the body does something automatically without you deciding to do it- it is involuntary 3. E.g to cause the heart to beat or to digest food 4. The autonomic nervous system carries nerve impulses to glands, smooth muscle and cardiac muscle
Label a graph of lung volume during breathing with "tidal volume", "vital capacity", "inspiratory reserve volume", "expiratory reserve volume", "residual volume", and "total lung capacity".
1. Tidal volume- the range between the peak and troughs of normal breathes- all the same size waves 2. Vital capacity- the range form the bottom of the lowest peak to the top of the highest 3. Inspiratory reserve volume- the range from the peak of the smaller waves to the peak of the large waves. 4. Expiratory reserve volume- the range from the trough of the smaller waves to the trough of the larger wave. 5. Residual volume- the range from the trough of the larger waves to 0 on the y-axis 6. Total lung capacity- the total range from 0 to the peak of the large waves
Draw a flow chart to show the process of blood clotting.
1. Tissue is damaged 2. Platelets are activated by damaged tissue 3. Platelets release the enzyme thromboplastin an seratonin (seratonin makes smooth muscle in walls of blood vessels contract- narrows and reduces blood loss) 4. In the presence of calcium ions, thromboplastin catalyses the conversion of prothrombin into thrombin 5. Thrombin, an enzyme, catalyses the conversion of fibrinogen (soluble globular protein) into fibrin (insoluble fibrous protein) 6. Fibrin molecules form a mesh 7. The fibrin mesh traps platelets and red blood cells to form a clot 8. The clot dries out to form a hard tough scab 9. The clot and scab minimise blood loss and minimise the entry of pathogens directly into tissues or the blood through broken skin
Give 3 reasons why scientists classify organisms.
1. To identify species- by using defined system of classification, the species an organism belongs to can be easily identified 2. To predict characteristics- if several members in a group have a specific characteristic, it's likely other species in the group will have the same characteristic 3. To find evolutionary links- species in the same group probably share characteristics as they have evolved from a common ancestor
Draw and label a diagram to show the microstructure of the interface between the glomerulus and the Bowman's capsule
1. To the left is capillary with blood plasma and endothelial cells with gaps between 2. Then there is the basement membrane 3. Then there is the podocytes 4. Then there is the Bowman's capsule which contains the filtrate
State the 3 types of stem cell and give examples of where they occur in animals.
1. Totipotent- A fertilised egg or zygote and the 8 or 16 cells in the first stages of mitotic divisions. 2. Pluripotent- Present in early embryos and are the origin of the different types of tissue within an organism 3. Multipotent- Haematopoetic stem cells in bone marrow are multipotent- various types of blood cell
Describe when a paired t-test would be used and when an unpaired t-test would be used to analyse data
1. Unpaired t-test compares two different subjects- two independent groups 2. Paired - compares the same subject/ the same group measured before and after and event/manipulation
Describe how urine testing is used to see if someone has been taking illegal drugs
1. Urine is tested for the presence of many different drugs including alcohol 2. If someone is suspected of having taken an illegal drug, they may be asked to provide a urine sample and this will be divided into two 3. The first sample may be tested by an immunoassay using monoclonal antibodies to bind to the drug or its breakdown product 4. If positive, then the second sample may be run through a gas chromatograph/mass spectrometer to confirm the presence of the drug
Describe how to produce stained sections (both transverse sections and longitudinal sections) of plant stems for viewing under a light microscope.
1. Use a scalpel to cut a cross-section of the stem (transverse or longitudinal)- very thin 2. Place the cut sections in water using tweezers, until you use them- stops drying out 3. Add drop of water to microscope slide add the plant section and add one or two drops of a stain - leave for 1 min 4. put cover slip on
Describe when a "Student's t-test" would be used to analyse data
1. Used to compare the mean values of two sets of data 2. To use this test the data collected must be normally distributed and enough data should be collected to calculate a reliable mean 3. Different sample sizes may be used
Describe the advantages of using phylogenetic trees as a form of classification as opposed to just using taxonomic groupings
1. Uses phylogeny to confirm classification groups or caused them to be changed 2. Produces continuous tree whereas classification requires discrete taxonomical groups- scientists aren't forced to put organisms into a specific group that they don't quite fit 3. The hierarchical classification can be misleading as it implies different groups within the same rank are equivalent.
Describe how the rate of photosynthesis can be measured.
1. Using a data logger that records data over time using sensors 2. The rate can be estimated by calculating the rate of oxygen produced, carbon dioxide used or increase in dry mass of a plant.
Describe the process of heamodialysis
1. Usually carried out in hospital 2. Blood leaves the patient's body from an artery and flows into the dialysis machine where it flows between partially permeable dialysis membranes 3. These membranes mimic the basement membrane of the Bowman's capsule. On the other side of the membranes is the dialysis fluid 4. During dialysis it is vital that patients lose the excess urea and mineral ions that have built up in the blood 5. It is equally important that they do not lose useful substances such as glucose and some mineral ions
Describe 3 adaptations that enable the body to return low pressure blood to the heart against gravity.
1. Valves 2. Many bigger veins run between big active muscles in the legs. When they contract they squeeze the veins forcing blood towards the heart. 3. Breathing movement of the chest act as a pump- pressure changes and the squeezing actions move blood in the veins of the chest towards the heart
Explain how core body temperature is increased if it drops below the optimum
1. Vasoconstriction 2. Decreased sweating 3. Raising the body hair or feathers 4. Shivering
State how core body temperature is decreased if it rises above the optimum. (endotherms)
1. Vasodilation 2. Increased sweating 3. Reducing the insulating effect of hair or feathers
Draw and label a diagram to show the arrangement of tissues within the liver
1. Venule from hepatic portal vein and arteriole from hepatic artery mix in the sinusoids 2. The sinusoids are surrounded by hepatocytes 3. There is a big white space in the middle which is the bile canaliculli 4. There are Kupffer cells on the hepatocytes
Describe the structure of capillaries.
1. Very small 2. Substances are exchanged through the capillary walls between the tissue cells and the blood 3. The gaps between the endothelial cells that make up the capillary walls in most areas of the body are very large- where many substances pass out of the capillaries into the fluid surrounding the cells
Draw a table to show 8 adaptations of hydrophytes and for each adaptation explain how it benefits the plant.
1. Very thin or no waxy cuticle- don;t need to conserve water 2. Many always-open stomata on the upper surfaces- maximising the number of stomata maximises gaseous exchange- no risk of loss of turgor- stomata open all the time and guard cells are inactive. Need to be on upper surfaces so are in contact with the air 3. Reduced structure to the plant- water supports the leaves so no need for the strong supporting structures 4. Wide, flat leaves- spread across the surface of water to capture as much light as possible 5. Small roots- water an diffuse directly into stem and leaf tissue- less need for uptake by roots 6. Large SA of stems and roots under water- maximises area for photosynthesis ad for oxygen to diffuse into submerged plants. 7. Air sacs- enable the leaves or flowers to float to the surface of the water 8. Aerenchyma- specialised parenchyma tissue forms in the leaves,stems and roots - many large air spaces- making leaves and stems more buoyant and forming low-resistance internal pathway form the movement of substances such as oxygen to tissues below the water.
Describe an example of how a hormonal weed killer works and explain why it is useful in agriculture
1. Weeds interfere with crop plants, competing for light, space, water and minerals 2. Scientists have developed synthetic auxins which act as very effective weedkillers 3. Many of the main staple foods around the world are narrow-leaved monocot plants- rice, maize, wheat 4. Most of the weeds are broad-leaved dicots 5. If synthetic dicot auxins are applied as weedkiller, they are absorbed by the broad leaved plants and affect their metabolism 6. The growth rate increases and becomes unsustainable so they die 7. The narrow-leaved crop plants are not affected and continue to grow normally, freed from competition 8. Auxins are cheap and simple to produce, have a very low toxicity to mammals and are selective
Define the term negative feedback
1. When a change away from the ideal triggers a reaction to bring the conditions to ideal 2. The mechanism by which homeostasis is achieved
Describe the role of major histocompatibility complex glycoproteins in the cytoplasm of macrophages at the end of phagocytosis.
1. When a macrophage has digested a pathogen it combines with antigens from the pathogen surface membrane with special glycoproteins in the cytoplasm called major histocompatability (MHC) 2. The MHC complex moves these pathogen antigens to the macrophage's own surface membrane becoming an antigen presenting cell 3. These antigens now stimulate other cells involved in the specific immune system response
Describe what the resting potential is
1. When a neurone is not transmitting an impulse the potential different across its membrane is known as a resting potential 2. In this state, the outside of the membrane is more positively charged than the inside of the axon 3. The membranes is said to be polarised as there is a potential difference across it 4. It is normally about -70mV 5. Some potassium ion channels are open (mainly those that aren't voltage-gated) 6. Sodium voltage-gated ion channels are closed
Describe 3 examples of when VOCs are used by plants to defend themselves
1. When cabbages are attacked by caterpillars, they produce a chemical signal which attracts the parasitic wasp. This insect lays its eggs in the caterpillars which are then eaten alive, protecting the plant. The signal from the plant also deters any other butterflies from laying their eggs 2. When apple trees are attacked by spider mites they produce VOCs which attract predatory mites that come and destroy the apple tree pests 3. Some types of wheat seedling produce VOCs when they have been attacked by aphids and these repel other aphids from the plant 4. Sometimes a VOC produced by a plant will also act as a pheromone so that neighbouring plants begin to produce the VOC before they are actually attacked
Describe the route oxygen takes from the air in the alveoli to haemoglobin and explain how the concentration gradient is maintained.
1. When erythrocytes enter the capillaries in the lungs oxygen levels in the cells are relatively low- makes steep concentration gradient between the inside of the erythrocytes and the air in the alveoli 2. Oxygen moves into the erythrocyte and binds with the haemoglobin 3. The arrangement of the haemoglobin molecule means once one oxygen molecule binds to a haem group the molecule changes shape, making it easier for the next oxygen molecules to bind to it- positive cooperativity 4. Because oxygen is bound to the haemoglobin, the free oxygen concentration in the erythrocyte stays low- steep diffusion gradient is maintained until all of the haemoglobin is saturated with oxygen.
Define RNA editing
1. When the nucleotide sequence of mRNA molecules are changed through base addition, deletion or substitution 2. Same effect as point mutations and can result in the synthesis of different proteins- increases the range of proteins that can be produced from a single mRNA molecule or gene 3. A type of RNA processing
Describe the process of germination in seeds including the role of plant hormones
1. When the seeds absorb water, the embryo is activated and begins to produce gibberellins 2. They in turn stimulate the production of enzymes that break down the food stores found in the seeds 3. The food store is in the cotyledons in dicot seeds and endosperm in monocot seeds 4. The embryo plant uses these food stores to produce ATP for building materials so it can grow and break out through the seed coat 5. Evidence suggests that gibberellins switch on genes which code for amylases and proteases- the digestive enzymes required for germination 6. There is also evidence suggesting ABA acts as an antagonist to gibberellins and that it is the relative levels of both hormones which determine when a seed will germinate
Describe the evidence supporting a link between auxin and apical dominance, and describe the evidence that suggests that this link is not directly causal.
1. When the shoot of the apex is removed, one or more lateral buds grow 2. When IAA is put on cut end of shoot after decapitation apical dominance is maintained-IAA can artificially maintain apical dominance 3. Auxin transport inhibitor placed below the shoot apex, lateral buds grow- IAA plays a role in maintaining apical dominance naturally 4. After decapitation auxin concentration of lateral buds increased suggesting it is not directly linked and other hormones must be at play 5. Evidence shows cytokinins stimulate lateral bud growth and auxins control the accumulation of cytokinins
Define the term "phloem loading" and state the two main ways this occurs.
1. When the soluble produts of photosynthesis are moved into the phloem form the sources by an active process 2. Two main ways plants load assimilates into their phloem for transport- symplast and apoplast route
Explain why some neurones are myelinated and others are unmyelinated.
1. When the stimulus is non urgent they don't need the very fast transmission e.g temperature change or a dull ache 2. When the stimulus is urgent they need to have fast a fast transmission to protect the body from danger e.g burning candle
Explain how guard cells can open and close stomata.
1. When turgor is low the asymmetric configuration of the guard cell walls closes the pores 2. When turgor is high- the cell swells and because the inner wall is less flexible than outer wall the cells become bean-shaped and open the pore. 3. When water becomes scarce hormonal signals from the roots can trigger turgor loss from the guard cell, which closes the stomatal pore
Explain how to use a light microscope to view a specimen at low and high powers.
1. When using low power lenses ( scanning or low power objective lens) use the coarse to roughly bring it to focus. 2. When using a high power use the fine adjustment knob.
Identify xylem and phloem from longitudinal cross section of stem
1. Xylem is relatively thin on the inside 2. Layer between and phloem is further to the outside
Draw, label and annotate a diagram of an antibody.
1. Y-shaped- made up of two identical long polypeptide chains called the heavy chains and two much shorter chains called the light chains 2. The chains are held together by disulfide brides as well as disulfide bridges within the polypeptide chain holding them in shape 3. Bottom of y is receptor binding site 4. Two ends of the branches of the y are the antigen binding sites- variable region - is a different shpa eon each antibody- gives it it's specificity 5. the rest is the constant region and is always the same
Draw and annotate an oxygen dissociation curve showing the percentage saturation of haemoglobin when exposed to a range of oxygen partial pressures.
1. a shallow S shape- starts with gradual incline, then is very steep, then begins to plateau 2. Where pO2 is low haemoglobin has a low affinity for oxygen so has a low saturation of oxygen 3. Where pO2 is high, haemoglobin has a high affinity for oxygen, so it has a high saturation of oxygen- maximum is 100% where every haemoglobin molecule is carrying 4 molecules of oxygen. 4. It is 2 shaped because saturation of haemoglobin can affect affinity- when haemoglobin combines with the first O2 molecule, its shape alters making it easier for other molecules to join. As it starts to get saturated it gets harder for more oxygen molecules to combine.
9 steps of ultrafiltration:
1. blood from renal artery enters smaller arterioles in the cortex 2. each arteriole splits into a glomerulus 3. this is where ultrafiltration takes place 4. arteriole that takes blood into each glomerulus is called the AFFERENT arteriole, and the arteriole that takes blood away from the glomerulus is called the EFFERENT arteriole 5. the efferent arteriole is smaller in diameter so the blood in glomerulus is under higher pressure 6. the high pressure forces liquid and smaller molecules in the blood out of capillary and into bowmans capsule 7. pass through 3 layers to get to the bowmans capsule and enter the nephron tubule - the pre of endothelial cells in capillary wall, the basement membrane and the epithelium (squamous epithelial cells and podocytes) of bowmans capsule. larger molecules like proteins and blood cells cant pass through and stay in blood 8. the liquid and small molecules now called filtrate pass along the nephron and useful substances are reabsorbed along the way 9. the filtrate flows through collecting duct and passes out of kidney along the ureter
State the rules for biological drawings.
1. include a title 2. state magnification 3. use a sharp pencil for drawings and labels 4. use white unlined paper 5. make it big 6. draw smooth continuous lines 7. do not shade 8. draw clearly defined structures 9. ensure proportions are correct 10. label lines should not cross and should not have arrow heads 11. label lines should be parallel to the top of the page and drawn with a ruler
Describe the roles of the regulatory gene, the structural genes the lac operon for the metabolism of lactose.
1. lac I is a regulatory gene- located near to the operon and codes for a repressor protein that prevents the transcription of the structural genes in the absence of lactose 2. Structural genes- code for three enzymes which are transcribed onto a single long molecule of mRNA but are translated into the 3 enzymes
decribe the 6 stages of selective reabsorption
1. useful substances leave tubules of nephrons and enter the capillary network thats wrapped aroung them 2. the epithelium of the wall of the pct has microvilli to provide a large sa for reabsorption of useful materials from the filtrate (in the tubules) into the blood (in the capillaries) 3. Useful solutes like glucose, amino acids, vitamins and some salts reabsorbed along the pct by active transport and facilitated diffusion 4. some urea also reabsorbed by diffusion 5. water enters blood by osmosis as water potential is lower than that of the filtrate. water reabsorbed from the loop of henle, dct and collecting duct 6. the filtrate that remains is urine and passes out of the ureter to bladder
Explain how a tissue slice might be misleading due to the very thin nature of the slice.
1. you can only see a cross-section of a cell not it's overall shape- you might not see the actual shape of the cell. 2. there are different organelles at different parts of the cell- you might miss structures that are inside the cell. 3. Its not actually the diameter of the cell just the diameter of the cross section.
Describe the characteristic features of Bacteria
70s ribosomes RNA polymerase contains 5 proteins
Define sugar phosphate backbone
A backbone is composed of alternating sugar and phosphate groups, that forms the structural framework of nucleic acids.
Define the term casparian strip
A band of waxy material called suberin that runs around each of the endodermal cells forming a waterproof layer
Define the term cell
A basic unit of life. Consists of cellular contents surrounded by a plasma membrane . All life is composed of these basic units whether it is unicellular or multicellular
Outline how an SEM works
A beam of electrons is fired at the surface of a specimen and the reflected electrons are collected to create a 3D image.
Outline how a TEM works
A beam of electrons is transmitted through the specimen and focused to produce an image.
Define breathing
A behaviour that you do by muscle contraction and relaxation
Define the term holoenzyme
A biochemically active compound formed by the combination of an enzyme with a coenzyme. The name of a precursor protein once it has be activated by the binding of a cofactor
Define the term proenzyme
A biologically inactive substance which is metabolized into an enzyme.
Draw and label a diagram of an amino acid.
A carbon atom with a carboxyl (COOH) and an amino group (NH2) attached on either side. They have a hydrogen above or below the carbon atom. And then also an R-group above or below the carbon atom.
Define the term tissue
A collection of differentiated cells that work together to perform a specialised function or functions.
Define the term organ
A collection of tissues that work together to perform a particular function in an organism
Define the term "antigen presenting cell".
A cell that displays foreign antigens complexed with major histocompatibility complexes on their surfaces
Define climate change
A change in global or regional climate patterns, and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.
Define the term mutation.
A change in the genetic material (a change to the base sequence) which may affect the phenotype of the organism.
Define mutation
A change in the genetic material which may affect the phenotype of the organism
Define positive feedback
A change in the internal environment of the body is detected by sensory receptors and effectors are stimulated to reinforce the change and increase the response
Define the term discontinuous variation
A characteristic that can only result in discrete values e.g. blood type
Define the term continuous variation
A characteristic that can take any value any value within a range e.g height
Describe the term polygenic
A characteristic that is controlled by a group of genes
Define a single bond
A chemical bond in which one pair of electrons is shared between two atoms
Define a double bond
A chemical bond in which two pairs of electrons are shared between two atoms
Define the term dimer
A chemical compound composed of two identical or similar monomers
Define the term antibiotic
A chemical or compound that kills or inhibits the growth of bacteria
Define the term recombinant chromatid
A chromatid that has undergone crossing over so that it now possesses some alleles from the maternal chromosome and some from the paternal chromosome.
Define single circulatory system
A circulatory system where the blood flows through the heart and is pumped out to travel all around the body before returning to the heart.
Define closed circulatory system
A circulatory system where the blood is enclosed in blood vessels and does not come into direct contact with the cells of the body beyond the blood vessels.
Define double circulatory system
A circulatory system where the blood travels twice through the heart for each complete circulation of the body. The first circulation blood is pumped by the heart to the lungs. In the second circulation oxygenated blood is pumped by the heart to the brain and body to supply cells with Oxygen
Define open circulatory system
A circulatory system with a heart but few blood vessels to contain the transport medium. The blood vessels open up to a pool of blood called the haemoceol
Define the term prosthetic group
A co factor that is tightly bound to an enzyme. A permanent feature of a protein.
What is murein?
A complex polymer formed from amino acids and sugars
Define renal dialysis
A process where the function of the kidney are carried out artificially to maintain the salt and water balance of the blood
Define the term passive process
A process which doesn't require energy
Define the term active process
A process which requires energy (ATP)
Define the terms "conjugated protein".
A protein with a non-protein group attached. they are globular proteins.
Define the term "fight or flight response"
A series of physical responses intended to help mammals survive by preparing the body to either run or fight
Define the terms monomer
A small basic molecular unit that makes up a polymer e.g. amino acids and monosccharides
Define the term tracheoles
A small pipe that branches of a trachea in insects and is used for gas exchange.
Define acinus
A small sac-like cavity in a gland, surrounded by secretory cells
Describe what is meant by a start codon
A start codon is the codon that signals the start of a sequence that codes for a protein.
Define embryonic stem cell
A stem cell found within an embryo. Zygotes and the cells of the very early embryos are totipotent. When the embryo has developed into the blastocyst (a mass of cells) they are now pluripotent, they remain like this until a dew days before birth.
Define multipotent
A stem cell that can only differentiate into a range of cell types within a certain type of tissue
State the sequence of events in an enzyme-controlled reaction.
A substrate binds to the active site forming an enzyme-substrate complex- lowers activation energy.
Draw a graph showing how pH affects the initial rate of an enzyme-controlled reaction.
A symmetrical graph with the peak at the optimum pH. It is a curved line up and down.
Define the term vascular system
A system of transport vessels in animals or plants
Define parallel exchange system
A system where both the water and blood flow in the same direction.
Define the term electrocardiogram
A technique for measuring tiny changes in the electrical conductivity of the skin that result from the electrical activity of the heart. This produces a trace which can be used to analyse the health of the heart
Explain why the percentage of adults with the ability to digest lactose increased?
Ability to digest lactose is a beneficial characteristic drinking milk prevented starvation reduced osteoporosis directional selection
Explain why a pH change away from the optimum decreases the rate of reaction.
Above and below the optimum temperature the H+ ions and the OH- ions can break the ionic and hydrogen bonds that hold the enzyme's tertiary structure in place. This changes the shape of the active site, so the enzyme is denatured.
Define the terms "absolute uncertainty" and "relative uncertainty or percentage error".
Absolute uncertainty- the extent by which the measurement could be out relative uncertainty- the ratio of the absolute uncertainty to the original value multiplied by 100
Describe the advantages and disadvantages of being an endotherm
Advantages 1. Can inhabit a wide range of habitats including places that get very cold 2. Can maintain a fairly constant body temperature regardless of external conditions 3. Can maintain high activity levels even at night and winter Disadvantages 1. High food requirements 2. More energy needed for metabolism 3. More of the food is used to maintain body temperature and so less is available for growth
Describe the advantages of, and challenges faced by, gas exchange systems operating in water rather than air.
Advantages: 1. Water loss isn't an issue 2. Water provides structural support which air doesn't Disadvantages: 1. Much lower oxygen concentration- lower conc. gradient- more difficult to obtain sufficient O2 2. Water is more viscous and dense than air.
State the 3 categories of reasons for maintaining biodiversity.
Aesthetic, economic, ecological
Name the types of cell that do alcoholic fermentation and the types of cell that do lactate fermentation.
Alcoholic fermentation- yeast and some plant root cells Lactate fermentation- animal cells
Interpret a graph of atrial pressure
Always relatively low/Highest when contracting but drops when left AV valve closes and walls relax/Then there is a build up of pressure as they fill with blood/Until a slight drop when AV valve opens
Define the term arrhythmia
An abnormal rhythm of the heart
Define acetylcholinesterase
An enzyme that causes rapid hydrolysis of acetylcholine. Its action serves to stop excitation of a nerve after transmission of an impulse
Define first messanger
An extracellular substance (hormone) that binds to a cell-surface receptor and initiates intracellular activity
Fermentation
Anaerobic respiration without the involvement of an electron transport chain.
Define the term monomer
An individual molecule that makes up a polymer.
*State the difference between the result of an inhibitory and a stimulatory drug that acts on the nervous system
An inhibitory drug results in less action potentials being created / a stimulatory drug creates more action potentials
Define the term anabolic reactions
Anabolism refers to chemical reactions in which simpler substances are combined to form more complex molecules. Anabolic reactions build new molecules and or store energy. And they normally require energy.
Explain why synapses are unidirectional
As the neurotransmitter receptors are only present on the postsynaptic membrane, impulses can only travel from the presynaptic neurone to the postsynaptic neurone
Hydrophilic
Attracts water Any charged or polar molecule, group or ion forms electrical bonds with water and dissolves.
Define the term "autoimmune disease" and name and describe 3 examples of autoimmune diseases.
Autoimmune disease- a condition or illness resulting from an autoimmune response- when the immune system acts against its own cells and destroys health tissue in the body 1. Lupus- immune system attacks cells in connective tissue which causes painful inflammation- affects skin, joints and heart and lungs 2. Rheumatoid arthritis- attacking cells in the joints which cases pain and inflammation 3. Type 1 diabetes- affects insulin-secreting cells of the pancreas
explain why water is a polar molecule
Because oxygen is more electronegative than hydrogen- it has a greater pull on shared electrons, the electrons are pulled closer to the oxygen atom which leaves hydrogen with a delta positive charge and oxygen with a delta negative charge
Explain why ions are only able to cross a membrane through a protein channel.
Because they are repelled by the hydrophobic interior of the membrane. So need to be transported in a protein channel.
Explain the importance of membrane bound proteins in chemical reactions.
Because they have to be in particular positions fr chemical reactions to take place.
Using the "polar nature of water" explain the how water can dome above the level of the glass container it is in, the shape of the meniscus in a glass measuring cylinder and capillary action in a narrow glass tube. (S+C)
Because water is cohesive as they form hydrogen bonds as they are polar. so they stick together and are difficult to split apart and so when they rise up over the level of heir container they form a dome this is called surface tension
Explain why the principle of macromolecules being able to be deconstructed into building blocks which can then be reconstructed into different macromolecules is the basis for life as we know it.
Because you can make loads of things which are important
Explain how a spirometer trace is different to a graph of the changes in lung volume during breathing.
Changes in lung volume graphs- measured in mL Spirometer trace- measured in volume of gas in spirometer/ dm^3 Changes in lung volume- peaks are for inspiratory and troughs are for expiratory Spirometer trace- peaks are for expiratory and trough for inspiratory.
Describe the term multifactorial
Characteristics which are dependent on a number of factors
Describe the causes of variation that result in continuous variation
Characteristics which show continuous variation are controlled by a number of genes and are also often influenced by environmental factors
Define chromosome mutation
Chromosome mutations affect the whole chromosome or number of chromosomes within a cell
State the formulae for the circumference and area of a circle.
Circumference: 2πr Area: πr^2
Carbohydrates- the name of the reaction that joins the building blocks together
Condensation reaction
Proteins- Name of reaction that joins the building blocks together
Condensation reaction
Draw a labelled diagram demonstrating the condensation of peptide bonds.
Condensation reaction- a peptide bond connects amino acids forming a dipeptide. This happens between the carboxyl group on one amino acid and the amino group of another amino acid and releases water (from and OH of the carboxyl group and H from the amino group)
State the name of the reaction that joins nucleotides to other nucleotides and the name of the reaction that breaks phosphodiester bonds.
Condensation reaction- releases water Hydrolysis reaction- breaks the bond using water
Define central nervous system
Consists of your brain and spinal cord
Explain why DNA replication is necessary.
DNA copies itself before cell divisions so that each new cell has the full amount of DNA. This is important for making new cells and for passing genetic information from generation to generation.
State the roles of DNA helicase in DNA replication.
DNA helicase breaks the hydrogen bonds between the two polynucleotide DNA strands.
Define the term semi-conservative replication.
DNA replication results in one old strand and one new strand present in each daughter DNA molecule
Name the stages in the cardiac cycle and outline what is happening at each stage.
Diastole- atria and then ventricles fill with blood/Atrial systole- atria contract /Ventricular systole- ventricles contract forcing blood out of heart.
Draw the structures of ribose and deoxyribose and identify the difference between the two pentose sugars.
Deoxyribose - on 2' carbon only has an -H below Ribose - on 2' carbon has an -OH below
Explain what determines how far a particular molecule travels in chromatography. *recap*
Depends on the solubility and interactions (hydrogen bonds) More soluble means it moves up further.
Define stimulus
Detectable change in the internal or external environment of an organism which is detected by the nervous system and can cause a response
Define the terms "simple diffusion"
Diffusion is the net movement of particles from an area of high conc to an area of low conc down the concentration gradient
State the transmission methods for the following plant diseases: ring rot, tobacco mosaic virus, potato blight, black sigatoka.
Direct transmission- ringrot, TMV, tomato and potato blight, black sigatoka Indirect transmission 1. Soil contamination- balck sigatoka spores and TMV spores 2. Vectors- wind, water, animals, humans all carry the spores of the pathogen
Describe what is meant by direct transmission of a pathogen, describe 2 clear examples (mode of transmission and pathogen) of each.
Direct transmission: The pathogen is transferred directly from one individual to another Examples 1. Kissing or any contact with bodily fluids of another person- bacterial meningitis, STDs 2. direct skin to skin contact- ring worm/ athlete's foot
Describe the advantages and disadvantages of being an ectotherm.
Disadvantages 1. Core body temperature is heavily dependent on their environment 2. Temperature of air can vary dramatically both between seasons and over a 24 hour period- problem for land ectotherms 3. Activity levels are severely reduced when it is cold 4. Restricted to tropical or temperate regions on land but can be found throughout all oceans Advantages 1. Many ectotherms living in water don't need to thermoregulate as the HSHC of water means the temperature of water does not change much 2. Need less energy for metabolism (lower metabolic demands) 3. Less food is needed 4. More of the food eaten can be used for growth
Describe the role of B effector cells
Divide to form plasma cell clones
Describe the meaning of each of the symbols in the equation for calculating Simpson's index of diversity.
E- sum of N- total number of organisms of all species n- the total number of organisms of a particular species D- Simpson's index of diversity 0-1
Explain the biological significance of a High latent heat of vapourisation
Effective as a coolant through sweating , panting and transpiration. As a large amount of energy is expended in evaporating sweat form the skin and overcoming hydrogen bonding. maintaining constant temperatures in cellular environments is important as enzymes are often only active in a narrow temperature range
Define the terms "active site"
The area of an enzyme with a shape complementary to a specific substrate, allowing the enzyme to bind to a substrate with specificity
Draw a diagram to show how a triglyceride is formed and broken down.
Ester bonds are forms by a condensation reactions where a water molecule is released- esterification Hydroxyl groups from the fatty acid tails and the glycerol interact to produce 3 water molecules and 3 ester bonds. When ester bonds are broken in a hydrolysis reaction where a water molecule is used up, the triglyceride breaks down into fatty acids and a glycerol.
Some antibiotics kill bacteria by disrupting the formation of peptidoglycan molecules. explain why these antibiotics kill bacteria and why they do not have any effect on eukaryotic cells
Eukaryotic cells do not have peptidoglycan cell walls and these antibiotics do not damage any other cell components (e.g., nucleus, ribosomes, mitochondria)
Describe how the process of forced expiration is different from normal expiration and suggest when it might be used.
Expiration can be forced- the internal intercostal muscles contract to pull the ribcage down and in. This is an active process rather than the passive process of normal expiration.
Define interspecific variation
The differences between organisms of different species
Define the term ectopic hearbeat
Extra heartbeats that are out of the normal rhythm
Define intraspecific variations
The differences between organisms of the same species
Define exocrine gland
Group of specialised cells which secrete chemicals through ducts into organs or to the surface of the body
Define the term variation
The differences in characteristics between organisms
Define the term "cell adhesion".
Glycoproteins play a role in cell adhesion, when cells join together to form tight junctions in certain tissues.
Carbohydrates- Bond that links the building blocks together
Glycosidic bond
Describe crossing over
Homologous pairs of chromosomes come together and pair up in Prophase 1. The chromatids twist around each other and bits of chromatids swap over. The chromatids still contain the same genes but now have a different combination of alleles.
Define specialised
Having a particular structure to serve a specific function.
Write a reversible equation to show how haemoglobin carries oxygen.
Hb + 4O2 ⇌ Hb(O2)4 Haemoglobin + oxygen ⇌ oxyhaemoglobin
Explain how the polar nature of water gives it a high specific heat capacity
Hydrogen bonds give water hshc. the hydrogen bonds between molecules can absorb a lot of energy so it takes a lot of energy to heat it up
Describe the structure of an alpha helix coil
Hydrogen bonds may form within the amino acid chain pulling it into a coil shape
Define hyperpolarisation
Hyperpolarisation is a change in a cell's membrane potential that makes it more negative
Define the term electronegativity
The measure of the tendency of an atom to attract bonding pairs of electron
Use the concept of "bond energy" to explain why photosynthesis requires energy from the sun and stores energy whereas respiration releases energy that can be used to make ATP.
In respiration the large organic molecules are broken down forming small inorganic molecules. So the total energy required to break all the bonds in a complex organic molecule is less than the total energy released in the formation of all the bonds in the smaller inorganic products. This reaction releases energy. In photosynthesis the reverse happens so organic molecules are made from small inorganic molecules so energy is required from the sun to build these molecules.
Draw a graph showing how enzyme concentration affects the initial rate of an enzyme-controlled reaction.
It is just a straight line If the substrate amount is limited it plateaus.
Define the terms "pinocytosis"
Is the endocytosis of liquid materials
Define the the term expiratory reserve volume
Is the extra volume of air you can force out of your lungs after the normal tidal volume of air you breathe out.
Define the term conservation`
Is the maintenance of biodiversity by preservation and careful management of the environment and of natural resources.
Define the the term inspiratory reserve volume
Is the maximum volume of air you can breathe in after normal inhalation.
Define the terms "accuracy",
Is the measure of the closeness of agreement between an individual test result and the true value. If a test result is accurate, it is in close agreement with the true value.
Define the terms "repeatability"
Is the precision obtained when measurement results are produced over a short timescale by one person using the same equipment in the same place
Define the terms "reproducibility"
Is the precision obtained when measurement results are produced over a wider timescale by different people using equivalent equipment in different but equivalent places.
Define the the term Total lung capacity
Is the sum of the vital capacity and residual volume- the volume of air in you lungs after maximal inspiration.
Explain the biological significance of water being adheisve
It allows capillary action (water rises up narrow tubes) and moves through narrow spaces as it adheres to the surface of them. E.g when water rises up the xylem vessels and through air spaces between particles in soil
Define the terms reversible inhibitor
It doesn't bind permanently to an enzyme
Draw a graph showing how the total amount of product produced from an enzyme-controlled reaction changes over time following the start of an experiment. Explain the shape of the graph and explain the significance of the gradient of the line at any one point.
It increases rapidly at the start then plateaus out quickly. This is because at the start there is a high substrate concentration, but this falls as more reacts.
Define phylogenetic tree
It is a diagram used to represent evolutionary relationships between organisms. Shows common ancestors
Describe the usefulness of anaerobic respiration.
It is a temporary emergency measure to keep vital processes running when oxygen cannot be supplied fast enough to respiring cells.
Explain why the genetic code is a triplet code, the value of it being non-overlapping and the reason for it being degenerate.
It is a triplet code because it takes a sequence of three bases to code for one amino acid. It is degenerate because there are 64 possible codons and only 20 different amino acids- so different codons will code for the same amino acid.
What is flourescence
It is the absorption and re radiation of light.
Describe how to investigate the effect of plant hormones on growth
Many different ways including: 1. Growing seeds hydroponically (in nutrient solution rather than soil), in serial dilutions of different hormones or applying different concentrations of hormones to the cut ends of stems or roots and observing the effects. 2. In most experiments it is important to make serial dilutions to observe the effects of different concentrations of the hormones as they can have different effects on growth at different concentrations 3. Experiments investigating the effect of hormones on plant growth usually involve large numbers of plants 4. When you have completed your measurements, the spread of data from each experimental group should be measured using standard deviation
Define the term "channel protein"
Membrane proteins that provide a hydrophillic channel through a membrane that allows passive movement of polar molecules and ions down a conc. gradient.
Define the term "partially permeable".
Membranes that allow some substances to cross but not others
Define the term metabolism
Metabolism is a term that is used to describe all chemical reactions involved in maintaining the living state of the cells and the organism. All reactions that occur in the body.
Define second messanger
Molecules that relay signals received at receptors at the cell surface to target molecule
Carbohydrates- Building blocks
Monosaccharide e.g glucose, fructose, ribose
Explain why all life needs to perform respiration
Needs energy to perform metabolic processes such as; transport, synthesis, movement
Name the functional unit of the kidney
Nephrons
Draw a diagram to summarise the light-dependent stage of photosynthesis and state where this occurs.
Non cyclic photo-phosphorylation: 1. Light is absorbed by pigments in photosystem 2. 2. The light absorbed excites electrons at the reactions centres of the photosystems. 3. The excited electrons are released from the reaction centre of PS 2 and are passed to an electron transport chain. Transfers to PS 1 (higher wavelength) 4. ATP is produced by the process of chemiosmosis. 5. The electron lost from the reaction centre of PS2 are replaced photolysis 6. Excited electrons are released from the reaction centre of PS1 passed to another electron transport chain, and ATP is again produced by chemiosmosis. 7. These lost electrons are replaced by the electron coming from PS2. 8. The electrons leaving the electron transport chain following PS1 are accepted, along with hydrogen ion, by the coenzyme NADP, forming reduced NADP.
Define the term "diploid"
Normal chromosome number- two chromosomes of each type- one inherited from each parent
Describe how purines and pyrimidines are arranged in the complementary base pairing rules.
One pyrimidine always binds to a purine- this maintains a constant distance between the DNA backbones.
Define obligate anaerobe
Organisms that cannot live in environments containing oxygen
Define the term "osmotic stress" and describe 5 factors that could put the body under osmotic stress
Osmotic shock or osmotic stress is a sudden change in the solute concentration around a cell, causing a rapid change in the movement of water across its cell membrane 1. Eating a salty meal 2. Drinking large volumes of liquid 3. Exercising hard 4. Running a fever 5. Visiting a very hot climate
Describe when a paired t-test would be used and when an unpaired t-test would be used to analyse data
Paired- to analyse the difference between the means of two data-sets where the data from both data-sets was collected from the same subject. Unpaired- where the data from both data-sets was collected from different subjects
Explain how transpiration results in water moving through the plant (the cohesion-tension theory), and state whether it is an active or passive process.
Passive process- Cohesion-tension theory 1. Water moves into the xylem down the water potential gradient 2. Root pressure/ high hydrostatic pressure at the bottom of the xylem 3. Water vapour is lost by transpiration form the top of the leaves 4. This creates a low hydrostatic pressure at the top of the xylem 5. Water under tension is pulled up in a continuous column 6. There is cohesion between the water molecules and adhesion between the water molecules and the xylem (hydrogen bonds with carbohydrates in the cell wall). 7. This results in capillary action 8. Water moves up the xylem by mass flow down the hydrostatic gradient- to replace water lost by evaporation-transpiration pull
Describe the relationship between photosynthesis and respiration, and use this to explain the importance of photosynthesis for consumers as well as producers.
Photosynthesis produces glucose Respiration uses the glucose to produce energy. This energy or the glucose is passed to consumers when they eat producers.
Write out the overall chemical reactions for photosynthesis and respiration.
Photosynthesis- 6CO2 + 6H2O ↔ C6H12O6 + 6O2 Respiration- C6H12O6 + 6O2 → 6CO2 + 6H2O
Define hydrophyte
Plants with adaptations that enable them to survive in very wet habitats or submerged or at the surface of water
Define electron carrier
Proteins that accept and release electrons
Define the term belt transect
Provides more information than the line transect; two parallel lines are marked and samples are taken of the area between the two lines
Describe the function of mineralocorticoids
Release from adrenal cortex is mediated by signals triggered by the kidney 1. Main one is aldosterone- helps control blood pressure by maintaining the balance between salt and water concentrations in the blood and body fluids.
Describe the role of the adrenal medulla and the functions of the hormones produced
Released when the sympathetic nervous system is stimulated. This occurs when the body is stressed Two hormones secreted by medulla: 1. Adrenaline 2. Noradrenaline
Hydrophobic
Repels water Any uncharged or non-polar molecule, group or ion doesn't form electrical bonds with water and doesn't dissolve. Hydrocarbon Phospholipid have both hydrophobic and hydrophilic regions.
Define the term anaerobic respiration
Respiration in the absence of oxygen
Define repolarisation
Restoration of the difference in charge between the inside and outside of the plasma membrane following depolarisation
State the difference between saturated, monounsaturated and polyunsaturated fatty acids/triglycerides.
Saturated fatty acids- don't have any double bonds between their carbon atoms in their hydrocarbon tails. this means they can pack together as they are straight and are Solid at RT Monounsaturated fatty acids/ polyunsaturated fatty acids- have at least one double bond between carbon atoms which causes the chain to kink. this means they can't pack together and are normally liquid at RT. Monounsaturated fatty acids only have one double bond. Poly have two or more double bonds.
Explain why saturated triglycerides tend to be solid (fats) at room temperature whereas unsaturated triglycerides tend to be liquid (oils).
Saturated triglycerides don't have kinks so can pack together tightly so are solid unsaturated triglycerides have kinks so can't pack together tightly making them Liquid at RT
Describe how to produce a temporary wet mount of living tissue.
Specimens are suspended in liquid such as water or an immersion oil. A cover slip is placed on from an angle, aquatic samples and other living organisms can be viewed this way.
SA and Vol of sphere
Sphere: SA: 4πr^2 Vol:4/3πr^3
Explain why insects will tend to keep spiracles closed when oxygen demands are very low.
Spiracles can be opened and closed by sphincters- the spiracle sphincters are kept close as much as possible to minimise water loss.
Define the term "cell mediated immunity" and suggest what it is particularly effective against.
T lymphocytes respond to cells of an organism that have been changed in some way e.g. by a virus infection, by antigen processing or by mutation (cancer cell) and to cells from transplanted tissue
Identify the part of an amino acid which is variable.
The R-group is the variable part of an amino acid. There are 20 different types of R-group
Suggest how the R-groups of amino acids are involved in catalysing reactions.
The R-groups contain features which are responsible for the tertiary structure. The tertiary structure determines the active site shape.
Define the term companion cell
The active cells found next to sieve tube elements that supply the phloem vessels with all of their metabolic needs
Define root pressure
The active pumping of minerals into the xylem by root cells that produces a movement of water into the xylem by osmosis
Define the term selective toxicity
The ability to interfere with the metabolism of a pathogen without affecting the cells of the host.
Define the term Classification
The act of arranging organisms into groups based on their similarities and differences
Desribe the structure and function of the cytoskeleton
The cytoskeleton has three components: 1. microfilaments are contractile fibres made of actin that bring about cell contraction during cytokinesis 2. microtubules are formed from the cylindrical protein tubulin and form scaffold like structures used both in the movement of organelles and vesicles and as spindle fibres in the segregation of chromosomes 3. chromatids in cell division/intermediate fibres give mechanical strength to cells
Outline the structure of the 3 components of the cytoskeleton.
The cytoskeleton is a network of fibres necessary for the shape and stability of the cell 1. Microfilaments- contractile fibres formed from the protein actin 2. Microtubules- globular tubulin proteins polymerised to form tubes to form a scaffold-like structure that determines the shape of the cell 3. intermediate fibres- these fibres give mechanical strength to a cell and help maintain their integrity
Why do we need staining?
The cytosol (aqueous interior) of cells and other cell structures are often transparent. stains increase contrast as different componenets within a cell take up stains to different degrees. the increase in contrast allows components to become visible so they can be identified
Define gas exchange
The diffusion of gases from an area of higher concentration to an area of lower concentration, especially the exchange of oxygen and carbon dioxide between an organism and its environment.
Define the terms "osmosis"
The diffusion of water through a partially permeable membrane down a water potential gradient. A passive process.
Define the term "Bohr effect" and explain its value in the transport of oxygen.
The effect of carbon dioxide concentration on the uptake and release of oxygen by heamoglobin. 1. The partial pressure of CO2 also affects oxygen unloading. 2. Heamoglobin gives up its oxygen more readily at a higher pCO2 .- gets more oxygen to cells during activity 3. The dissociation curves shifts to the right but is still the same shape
Define relative energy value
The energy liberated in aerobic respiration
What is high specific heat capacity
The energy needed to raise the temperature of 1 gram of a substance by 1 degrees Celsius
Define generic name
The first word in binomial nomenculture that indicates the organism's genus
Define the term opercular valve
The flap that allows the oppeculum to be moves outwards whilst keeping it closed
Define ultrafiltrate
The fluid that passes into the tubules of the nephron after having been filtered through the Bowman's capsule under high pressure
State the site of oxidative phosphorylation within cells.
The folded membrane (cristae) of mitochondria.
Define the term "tertiary structure" of a protein, and describe how it is held in place (include all the different possible bonds).
The folding of a protein into its final shape it often includes sections of secondary structure. the coiling or folding of sections of proteins into their tertiary structures brings R-groups of different amino acids close enough together to interact and further folding will occur.
Define the term adhesion
The force of attraction between unlike molecules
Define transpiration pull
The force which aids in drawing the water upward from roots to leaves.
Define apical dominance
The growth and dominance of the main shoot as a result of the suppression of lateral shoots by auxin.
Describe the structure of The Heart
The heart is made of cardiac muscle, which contracts and relaxes in a regular rhythm, it doesn't get fatigued like skeletal muscle /The coronary arteries supply the cardiac muscle with the oxygenated blood it needs to keep contracting and relaxing all the time/The heart is surrounded by inelastic pericardial membranes which help prevent the heart form over-distending with blood
Describe what happens during diastole
The heart relaxes/Higher pressure in the pulmonary artery and aorta closes the SL valves to prevent backflow to ventricles/Blood moves into atria from veins, this increases the pressure of the atria/This means the ventricle pressure falls below that of the atria so the AV valves open/Some blood moves passively into the ventricle
Define the term taxonomic group
The hierarchical groups of classification- domain, kingdom, phylum, class, order, family, genus, species
Describe and explain the results you would expect to see in an investigation into how the rate of diffusion is affected by surface area.
The higher the surface area to volume ratio is the faster diffusion will occur.
Describe and explain the results you would expect to see in an investigation into how the rate of diffusion is affected by temperature.
The higher the temp the faster the rate of diffusion
Describe how a spirometer trace would differ during exercise as compared to the trace before exercise started.
The horizontal distance from peak to peak is shorter. Vertical distance between peak to trough is larger.
Explain how a non-competitive inhibitor affects the rate of an enzyme-controlled reaction.
The inhibitor binds to the enzyme away from its active site. The site they bind to is the allosteric site. This causes the active site ti change shape so the substrate molecules can no longer bind to it. Increasing the substrate concentration won't make any difference as enzyme activity is still inhibited
state how the body detects the difference between a small and a large stimulus
The larger the stimulus the more frequent the nerve impulses/action potentials
Define locus
The locus of a gene refers to the position of the gene on the chromosome
Define transpiration
The loss of water vapour from the stems and leaves of a plant as a result of evaporation from the cell surfaces inside the leaf and diffusion down a concentration gradient out through the stomata
Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.
The lungs are relatively close to the heart, and the lungs are much smaller than the rest of the body/The right side has to pump blood a relatively short distance and only has to overcome the resistance of the pulmonary circulation/The left side has to produce sufficient force to overcome the resistance of the aorta and arterial systems of the whole body and move blood under pressure to the whole body
Define pre mRNA
The mRNA transcribed from the DNA before any post-transcriptional regulation to remove introns
Define the term sieve tube element
The mains cells of the phloem that have a greatly reduced living content and sieve plates between the cells
Define thermoregulation
The maintenance of a relatively constant core temperature
Define homeostasis
The maintenance of a stable equilibrium in the conditions inside the body
Define the term "Vmax".
The maximum rate of velocity of an enzyme catalysed reaction.
Describe the importance of the cytoskeleton in movements of chromosomes
The movement of chromosomes when they separate during cell division depends on contraction of microtubules in the spindle
Describe the importance of the cytoskeleton in movements of cilia and flagella
The movement of cilia and flagella is caused by cytoskeletal protein filaments that run through them. so in the case of single cells that have flagellum (sperm cell) the cytoskeleton propels the whole cell
Define the term habitat biodiversity
The number of different habitats found within an area
Define the term species biodiversity
The number of different species and the abundance of different species in an area
Define heart rate
The number of heartbeats per unit of time, usually per minute
Define node
The points where new lines branch off
Define the term chiasma (chiasmata)
The points where two homologous chromosomes have become twisted around each other and break in order to exchange a section of the chromatid.
Describe the change in the human population since 1800.
The populations now is over 7 times more than in 1800 and over double what it was in 1960s.
Define p-value
The probability that the null hypothesis is true
Define ultrafiltration
The process by which blood plasma is filtered through the walls of the Bowman's capsule under pressure
Define senescence
The process by which cells irreversibly stop dividing and enter a state of permanent growth arrest without undergoing cell death. Occurs before abscission and is inhibited by cytokinins
Define differentiation
The process of a cell becoming differentiated. Involves the selective expression of genes in a cell's genome.
Define the term transcription
The process of copying sections of DNA base sequence to produce smaller molecules of mRNA, which can be transported out of the nucleus via the nuclear pores to the site of protein synthesis.
Define the terms "receptor protein".
Usually glycoproteins, they detect the presence of an extra-cellular chemical and cause a response in the cell
Define global warming
The rising in the Earth's mean surface temperature.
Define non-random sampling
The sample is not chosen at random, it can be opportunistic, stratified or systematic.
Define sarcomere
The sarcomere is the functional unit of the myofibril. When a muscle cell contracts the sarcomere shortens.
Define binomial nomenculture
The scientific naming of a species with a Latin name made of two parts- the first indicating the genus and the second the species
Define Distal convoluted tubule
The second twisted section of the nephron where the permeability of the walls varies in response to ADH levels in the blood
Define specific name
The second word in binomial nomenculture that indicates the organism's species
State the location and function of the septum in the heart.
The septum is the inner dividing wall of the heart/It prevents the mixing of oxygenated and de-oxygenated blood
Describe the significance of the sequence of bases in a DNA strand for its function.
The sequence of bases allow it to carry coded information for the synthesis of proteins.
Define the terms complementary shape.
The shape of the active sites of enzymes are exactly complementary to the shape of the substrate. Lock and Key hypothesis
Define the term antisense strand
The strand of DNA that runs 3' to 5' and is complementary to the sense strand, it acts as a template strand during transcription.
Define the term sense strand
The strand of DNA that runs 5' to 3' and contains the genetic code for a protein.
Define synaptic knob
The swollen end of the presynaptic neurone. It contains many mitochondria and large amounts of endoplasmic reticulum to enable it to manufacture neurotransmitters
Define the term chemiosmosis
The synthesis of ATP driven by the flow of protons across a membrane
Define the term photophosphorylation
The synthesis of ATP from ADP and phosphate that occurs in a plant using light energy absorbed during photosynthesis.
Define scientific name
The taxonomic name of an organism that consists of its genus and species
Define the term affinity for oxygen
The tendency a molecule has to bind with oxygen
Define the term oncotic pressure
The tendency of water to move into the blood by osmosis as a result of plasma proteins
Suggest why it is not possible to remove all the air from the lungs
The thorax/rib cage/ lungs cannot be completely compressed The trachea and bronchi are held open by cartilage Bronchioles/alveoli are held open by elastic fibres
Define the term translocation
The transport of organic solutes around a plant in the phloem
Define circulatory system
The transport system of an animal
Define the term vascular bundles
The vascular system of herbaceous dicots made up of a xylem and phloem tissue
Describe what happens during atrial systole
The ventricles are relaxed/The atria contract decreasing the volume inside the chambers/This pushes blood into the ventricles through the AV valves/Causes slight increase in ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria.
Define response
The way a body reacts to a stimulus
Describe the disulfide bonds in the tertiary structure
These are covalent and the strongest of the bonds but only form between R-groups that contain sulfur atoms
Define the term ultrastructure
They are the features of a cell which can be seen using an electron microscope
Explain the role of extracellular enzymes in general..
They breakdown large nutrient molecules into smaller molecules by the process of digestion.
Describe what causes ADH to be released from the posterior pituitary gland.
When osmoreceptors detect changes in water potential of the blood
Define mass of fluid
When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
State the function of the smooth muscle fibres i the bronchus
To constrict the bronchus to control the movement of air
State the stages in protein synthesis
Transcription- an mRNA copy of a gene is made in the nucleus Translation- amino acids are joined together by a ribosome to make a polypeptide chain
Draw a diagram to show the process of the Krebs cycle.
Two Cycles happen at the same time 1. Acetyl CoA delvers an acetyl groups (whats left of the glucose from pyruvate) to the Krebs cycles 2. The two-carbon acetyl group combines with four-carbon oxaloacetate to form six-carbon citrate 3. The citrate molecule undergoes decarboxylation and dehydrogenation producing one reduced NAD and carbon dioxide. A five-carbon compound is formed. 4. The five-carbon compound undergoes further decarboxylation and dehydrogenation reactions eventually regenerating oxaloacetate and so the cycle continues 5. While oxaloacetate is regenerated, ATP is produced by substrate level phosphorylation- direct transfer of a phosphate group from an intermediate compound to ADP 6. Also produced is more CO2, two more reduced NADs and one reduced FAD are produced.
Define the term sister group
Two descendants that split form the same node are called sister groups
Describe the roles of the pancreas
Two main functions: 1. Exocrine gland- to produce enzymes and release them via a duct into the duodenum 2. Endocrine gland- to produce hormones and release them into the blood
Define antiparallel
Two parallel strands that are arranged so they run in opposite directions
Define chromatin
Uncondensed DNA in a complex with histones
Describe how to choose an appropriate number of significant figures, or decimal places to present data.
Use the highest number of decimal places in the question for your answer.
Describe when a students T-test would be used to analyse data
Used to compare the means of data values of two populations. The data must be normally distributed and enough data must be collected to calculate a reliable mean
Describe when a Spearmen's rank correlation coefficient would be used to analyse data
Used to consider the relationship between two sets of data- to see if there is a correlation
Name the two useful products, the waste product, and the requirements, of the light-dependent stage of photosynthesis.
Useful- ATP and reduced NADP/Waste product- Oxygen/Light is needed for energy to excite electrons
Describe the causes of variation that result in discontinuous variation
Variation determined purely by genetic factors falls into the discontinuous category. Most characteristics are controlled by a single gene
Write an equation to link ventilation rate with breathing rate and tidal volume.
Ventilation rate= breathing rate * tidal volume
Explain why the walls of the ventricles are thicker than the walls of the atria.
Ventricles have to pump blood out of the heart/Atria only need to move blood to the ventricles
Define synaptic vesicle
Vesicles containing neurotransmitters. The vesicles fuse with the presynaptic membrane and release their contents into the synaptic cleft
Describe the Hydrophobic and Hydrophillic interactions in the tertiary structure
When Hydrophobic R-groups are close together in the protein, they tend to clump together. This means that hydrophillic R-groups are more likely to be pushed to the outside which affects how the protein folds up into its final structure.
Define the term epidemic
When a communicable disease spreads rapidly to a lot of people at a local or national level
Define the term "herd immunity".
When a significant number of people have been vaccinated, this gives protection to those who do not have immunity - herd immunity - as there is minimal opportunity for an outbreak to occur. Helps people who can't get vaccinated- young, old or immunosupressed people
Describe random assortment of chromosomes
When homologous pairs line up in metaphase 1 and are separated in anaphase 1, it's completely random which chromosome from each pair ends up in which daughter cell.
Explain why horses and donkeys are separate species, and why mules are not given a scientific name and are not a separate species.
When horses and donkeys breed they produce infertile offspring. Mules are the offspring of a donkey and a horse. they are infertile because their cells contain an odd number of chromosomes. Because it's infertile they are not classified as a species- so no scientific name
Explain how scientific names of species are derived from the classification of a species and state the conventions used in writing them
Write in italics or underline the name. It should be written in lower case except for the first letter of the genus name.
Describe histograms
X-axis - class width- write measuring thing- height etc Y-axis - Frequency density= frequency/class width
Define homeobox genes
a group of genes responsible for the development of body plans. Homeotic/regulatory genes contain a homeobox
Define the term "macromolecule".
a macromolecules are complex molecules with a relatively large molecular mass. polymers are a group of macromolecules
fluorescence
a material absorbs light at one wavelength and then emits light at a longer wavelength
Define the term dipole
a molecule that has both positive and negative charges due to uneven distribution of charges
Define the term "triose sugar" and name an example.
a monosaccharide composed of 3 carbons e.g L-Glyceraldehyde and D-Glyceraldehyde
Define pentose sugar
a monosaccharide composed of 5 carbons
Define hexose sugar
a monosaccharide composed of 6 carbons
What is a microscope?
an instrument which enables you to magnify an object hundreds, thousands and even hundreds of thousands of times
Outline the structure and functions of bacterial chromosome in prokaryotic cells
circular chromosomes`
What is sickle cell anemia?
erythrocytes develop abnormally as mutation in gene coding for haemoglobin. substitution of one base. thymine replaces adenine, making the sixth amino acid valine instead of glatamic acid on the beta haemoglobin chain. Glutamic acid is hydrophilic but valine is a hydrophobic amino acid. when the partial pressure of oxygen is low and haemoglobin dissociated from oxygen the hydrophobic valine binds to hydrophobic regions on adjacent haemoglobin molecules and this aggregation deforms the shape of erythrocytes causing them to be sickle shaped. they are less flexible and have difficulty moving through capillaries resulting in reduced oxygen delivery to tissues causing anaemia.
Draw a labelled diagram showing the basic structure of a triglyceride.
fatty acid tails attached to one molecule of glycerol. they are synthesised by the formation of an ester bond. between each fatty acid and the glycerol
Explain benefits of being heterozygous for sickle cell anaemia
in homozygous individuals there are two copies of mutant alles present. heterozygous individuals only get mild symptoms but are resistant to malaria.
Describe the difference between in situ and ex situ conservation
in situ- within the natural habitat ex situ- out of the natural habitat
state why lasers are used to provide illumination
increase intensity of light
excretion of waste products from the body
maintains normal metabolism and homeostasis by helping to keep the levels of certain substances in the blood roughly constant
What else are found connected to each lobule?
many branches of the hepatic artery, hepatic portal vein and bile duct
Describe the significance of the position of the two pinholes
the positions of the two pinholes means the ligght waves from the laser follow the same path as the light waves radiated when the sample fluoresces. this means they will both have the same focal plance hence the term confocal
what does the homeodomain protein/s do in development of body plans?
the proteins bind to dna at the start of a developmental gene, activating or repressing transcription and so altering the production of proteins involved in the development of the body plans
Define somatic nervous system
this system is under conscious control used when you voluntarily decide to do something
Define autonomic nervous system
this system works constantly under subconscious control and used when the body does something automatically
Main 2 functions of the kidneys:
to excrete waste products and to regulate water potential of the blood
when preparing specimens for electron microscopy changes in...
ultrastructure of cells are inevitable during the processing samples must undergo
What is Gram Stain Technique?
used to separate bacteria into 2 groups, gram-positive bacteria and gram-negative bacteria. crystal violet is first applied to a bacterial specimen on a slide, then iodine which fixes the dye. the slide then washed with alcohol. the gram positive bacteria retain the crystal violet stain and will appear blue/purple under a microscope. gram negative bacteria have thinner cell walls and therefore lose the stain. they are then stained with safranin dye called a counterstain. these bacteria will them appear red. gram positive bacteria are susceptible to the antibiotic penicillin, which inhibits the formtion of cell walls. gram negative baceria have much thinner cell walls that are not susceptible to penicillin
Where is illumination provided from in a CLM?
usually prodived by a light underneath the sample. opaque specimens can be illuminated from above with some microscopes
Structures unique to plant cells are:
vacuoles and chloroplasts
Future uses for advanced optical microscopy:
virtual biopsies particular suspected skin cancer
What is Cirrhosis?
when cells of the liver die and scar tissue blocks blood flow
