Biology and Chemistry Revision
Effect of exposing animal cell to isotonic solution
-Water potential same inside and outside of cell. -No net movement of water. but water molecules still pass into and out of the cell in equal amounts. -Cell stays the same.
Effect of exposing plant cell to isotonic solution
-Water potential same inside and outside of cell. -No net movement of water. but water molecules still pass into and out of the cell in equal amounts. -Cell stays the same.
Phagocytes
-White blood cells that engulf and digest unwanted cells, such as damaged body cells or pathogens. -Lobed nucleus. -Larger than red blood cells.
Why is colour blindness much rarer in females than males?
Females need two copies of the recessive alleles for colour blindness, whilst males only need one. So males express this characteristic even if it is recessive.
How does fertilisation occur in plants
Fertilisation Occurs when a male gamete from a pollen grain fuses with a female gamete inside an ovule. This forms a diploid zygote, which grows into an embryo plant. In plants, unlike animals, the gametes are not formed directly by meiosis. Instead, meiosis is used in the production of pollen grains and the embryo sac and the gametes are then formed inside these structures by mitotic divisions.
What is the trend in ionisation energy down group 2?
First ionisation energy decreases down Group 2. This provided evidence that electron shells really do exist.
Where is energy stored in ATP
In the covalent bonds between the phosphate groups (greatest energy between second and third)
What is the solubility of Calcium Hydroxide?
It is reasonable soluble in water.
What do we use Empirical formula for?
It is used for Giant Covalent compounds and Ionic compounds.
What are the uses of Calcium Hydroxide?
It is used in agriculture to neutralise acidic soils.
What is the Structural Formula?
It shows the unique arrangement of atoms in a molecule in its simplified form, without showing all the bonds.
Why is Chlorine classed as a Catalyst?
It speeds up the breakdown of the Ozone while being reformed as others are produced.
What happens if Chloric (I) water is tested with Litmus paper?
It turns Red due to being an acid, then turns white due to Chloric (I) Acid being a bleaching agent.
Breaking of ester bond
Hydrolysis reaction: Molecule of water is added to each ester bond to break it apart, and the triglyceride splits up into three fatty acids and one glycerol molecule.
How are glycosidic bonds broken
Hydrolysis reaction: Molecule of water reacts with the glycosidic bond, breaking it apart
Why are lipids insoluble in water
Hydrophobic hydrocarbon tails
Transmission of measles
Inhalation of droplets of moisture containing the virus (morobillivirus) - It is highly infectious, so a high proportion of people who come into close contact with infected person will also get the disease.
Monohybrid inheritance
Inheritance of a single gene
Dihybrid inheritance
Inheritance of two genes
Pyrimidine bases
Made of one carbon-nitrogen ring: 1. Cytosine 2. Thymine 3. Uracil
What is the theoretical yield?
The theoretical yield is the mass of the product that should be formed in a chemical reaction. It assumes no chemicals are 'lost' in the process.
Quaternary structure definition
The three dimensional arrangement of two or more polypeptides, or of a polypeptide and a non-protein compononet such as haem, in a protein molecule.
Lymphocytes
-White blood cells that respond to particular pathogens by secreting antibodies or by directly destroying them. -Each lymphocyte is able to identify one particular pathogen, and respond to it by secreting one particular type of antibody or by attacking it.
Collagen steps
1. Helical polypeptide chains x3 2. Collagen triple helix 3. Fibril 4. Fibre
Lines of defense
1st line: prevents pathogens from entering the system (skin, tears, mucus, gastric juice) 2nd line: Phagocytes (macrophages and neutrophils) 3rd line: Lymphocytes T-lymphocytes = T killer cells B-lymphocytes = antibody secretion
Which cells provide the energy needed for the active transport of solutes into the sieve tube elements
Companion cells
How is Ammonia a Nucleophile?
Despite not having a charge, it is still a Nucleophile because it has a lone pair of electrons which it can donate.
What is a Maxwell-Boltzman distribution? Where is the most Probable energy?
It is a plot of the number of gaseous molecules against the energy they have at a fixed temperature. The energy value of the peak is the most probably energy (Emp). of the molecules.
How is Carbon monoxide dangerous?
It is a poisonous and odourless gas, which can inhibit the oxygen-carrying ability of the blood.
When does the thymus gland disappear
During puberty.
How do Group 2 metals react with cold water?
They react with increasing vigour down the group to form Hydroxides, which make the water alkaline if soluble.
Function of coenzyme A
Transfers acetate between molecules
What are the two haploid nuclei in pollen grains called?
Tube nucleus Generative nucleus
Benign tumours
Tumours which do not spread from their site of origin
Malignant tumours
Tumours which spread throughout the body, and invade other tissue, eventually destroying them
Examples of molecules that can diffuse through the plasma membrane
Water CO2 O2
What other uses does Chlorine have?
Water Treatment - Drinking Water and Swimming Pools. Extraction of Titanium. Bleaches. Weedkillers and Pesticides. Dyes and Pharmaceuticals.
Basic buffer
Weak base and a salt of a weak base
What is addition polymerisation?
When monomers (eg. alkenes) are joined together in the presence of high pressure and a suitable catalyst. An addition polymer is formed, such as a polyalkene).
Flaccid plant cell
When plant cell is exposed to hypertonic solution
Plasmolysis
When the cytoplasm of a plant cell shrivels and the plasma membrane pulls away from the cell wall when the cell loses water by osmosis due to exposure to a hypertonic solution
Structure of Tollen's Reagent
[Ag(NH3)2]+
Substance produced when Al3+ metal aqua ion reacts with Sodium carbonate
[Al(H2O)3(OH)3] White Ppt
Substance produced when Al3+ metal aqua ion reacts with dilute NH3
[Al(H2O)3(OH)3] White Ppt
Formula of Al3+ metal aqua ion in soln
[Al(H2O)6]3+
Units of rate
mol dm^-3 s^-1
A lower percentage saturation of Hb with oxygen shows...
more O2 is released
The left side of the heart pumps...
oxygenated blood to the rest of the body
pH of Cu2+ metal aqua ion in soln
pH 5/6
Half equivalence
pH = pKa
What is the ideal gas equation?
pV=nRT p = pressure in pascals V = Volume in m3 n = number of moles R = 8.31 the gas constant T = temperature measured in kelvin
Equation for Measuring ∆H of a reaction
q = mc∆T ∆H = q/mol m = g or cm3 c = Jg-K-, is the specific heat capacity, the amount of heat needed to raise the temperature of 1g of a substance by 1 K q= J
Biconcave disc shape of red blood cells increases the....
surface area to volume ratio allowing rapid diffusion of oxygen into and out of the cell.
Cells involved in specific immune response
- B-cells - T-cells
Blood pressure in veins
-Blood is at very low pressure. -Blood is very far from the pumping effect of the heart.
Factors affecting % saturation of O2 in haemoglobin
-Partial pressure of oxygen -pH
Adaptations of phloem
-cell wall with many plasmodesmata. -few organelles but no nucleus -perforated end walls = sieve plates -companion cell with nucleus and many mitochondria for actively loading sucrose etc.
Mehcanisms that help with transpiration stream
-cohesion and tension -adhesion -root pressure
Parts of airway system (6)
-epithelium -cilia -goblet cells -cartilage -smooth muscle -elastic fibres
Components of veins and arteries
-lumen -endothelium -smooth muscle -elastic fibres -fibrous tissue -connectvie tissue
Resolving limit of electron
0.2nm
Glycosidic bond in sucrose
1-2 glycosidic bond
Glycosidic bond in lactose
1-4 glycosidic bond
The three domains
1. Archaea 2. Bacteria 3. Eukarya
tRNA features
1. Folded molecule made up of a polynucleotide strand folded into a clover shape. 2. Has a binding site at one end where a specific amino acid attaches to. 3. Has a specific sequence of three bases = anticodon
Methods of systematic sampling
1. Line transect 2. Belt transect
Sieve tube element features
1. Living 2. End walls (sieve plates) 3. Contain cytoplasm (thin layer) and a few organelles but no nucleus 4. Cell wall made of cellulose 5. Companion cell associated with each cell
Adaptation of phloem tissue (simple)
1. Sieve plates 2. Companion cell 3. No nucleus, thin layer of cytoplasm, few organelles 4. Many plasmodesmata in walls
What is unaffected by penicillin
1. Viruses: They don't have a cell structure, so no cell wall. 2. Human cells: - Animal cells don't have cell walls. - Eukaryotes have different proteins (enzymes) to that of bacteria.
What is reliability?
1. When results can be consistently reproduced when experiment or study is repeated. 2. When values are close to mean
Diameter of eukaryotes
10-100 micrometers
Problems with treatment of malaria
2. Drug cost 3. Not likely to make available to all communities
Size of virus
20-300nm
Resolving limit of light
200nm
Wavelength of light
400nm
Number of chromosomes in humans
46 (diploid number)
pH of Fe2+ metal aqua ion in soln
5/6
Polymer
A large molecule consisting of many repeating, similar or identical monomers linked together.
Cisplatin
A platinum containing complex ion with a square planar shape that can be used as an anti-cancer drug.
Translation definition
A process in which amino acids are linked together to form polypeptide chains, following the order of bases on the mRNA.
Haemoglobin
A protein found in blood that helps to transport oxygen around the body.
Self
A substance produced by the body that the immune system recognises, so does not stimulate an immune response.
Inhibitor
A substance that slows down the rate at which an enzyme works.
Disaccharide
A sugar molecule consisting of two monosaccharides joined together by a glycosidic bond.
How is ATP produced
ADP -> ATP Energy released during respiration/photosynthesis is used to attach a third phosphate group to adenosine diphosphate to form ATP
How is ATP synthesised?
ADP and inorganic phosphate join using energy from an energy-releasing reaction e.g. breakdown of glucose in respiration. Energy is stored in phosphate bond.
What is made when energy is released from glucose during respiration?
ATP
Major products of oxidative phosphorylation
ATP H2O NAD/FAD
Products of non-cyclic photophosphorylation
ATP Reduced NADP O2
What two substances from the light dependent reaction are needed to keep the calvin cycle going?
ATP H+ ions form reduced NADP
What is transferred from the light dependent reaction to the light independent reaction?
ATP - transfers energy Reduced NADP - transfers hydrogen Used to make glucose from CO2
Why do animals need energy?
Active transport DNA replication Cell division Protein synthesis Muscle contraction Maintentance of body temperature
Role of oxygen in oxidative phosphorylation
Acts as electron acceptor
Phosphorylation
Adding phosphate to a molecule
General structure of neurones
All neurones have cell body with nucleus (plus cytoplasm and all other usual organelles) Cell body has extensions that connect to other neurones : -dendrites: carry nerve impulses towards cell body -axons: carry nerve impulses away from cell body
Genome
All of an organism's genetic material
Community defintion
All of the living organisms, of all species that are found in a particular ecosystem at a particular time.
Homogeneous reaction
All reactants and products are in the same state
What is a Spectator Ion?
An ion that is not changing state or oxidation number.
Solubility + Use of Ba(OH)2
Ba(OH)2 is very soluble in water hydroxide ions are produced so the solution is very alkaline as a result of Ba(OH)2 dissolving Ba(OH)2 + aq → Ba2+ + 2OH-
Cause of tuberculosis
Bacterium: 1. Mycobacterium tuberculosis 2. Mycobacterium bovis (rare)
Cause of cholera
Bacterium: Vibrio cholerae
Which ones contain red blood cells (blood, tissue fluid, lymph)
Blood
Tumour
Cell masses formed as a result of uncontrolled cell division, caused by mutation of genes.
Function of glycolipids in plasma membrane
Cell recognition Adhesion to neighbouring cells to form tissue
How do cells communicate with each other?
Cell signalling -To control processes inside the body and respond to stimuli
Effectors
Cells that bring about a response to a stimulus
Sex linked disorders
Colour blindness Haemophilia
Crenation
Contraction of a cell after exposure to a hypertonic solution, due to the loss of water through osmosis
Substrate level phosphorylation
Direct transfer of phosphate from one molecule to another.
v
Frequency of light absorbed
homogeneous
In the same state as the reactants
Example of a vector for malaria
Mosquitos
Autosomes
Non-sex chromosomes
Factors affecting rate of enzyme controlled reaction
Temp, PH, enzyme conc, substrate conc, presence of a catalyst
What are the conditions for Thermal cracking?
Temperature of 700-1200k Pressure of 7000kPa
Why isn't the product released yet when the enzyme-product complex is formed
Temporary bonds are formed (ionic and hydrogen bonds) that anchor the substrate in the active site
Examples of where collagen can be found
Tendons Blood vessel walls
Differentiation
The process by which stem cells become specialised
Name two types of Cracking:
Thermal Cracking and Catalytic Cracking
What metal is exacted using an active metal?
Titanium (TiO2) Temperature: 1st Stage ~900 2nd stage ~500
What flame colour is Magnesium?
White
Structural proteins in lac operon
X Y A
Sex-chromosomes
X and Y chromosomes
What is the general ionisation equation?
X(g) => X+ = e-
Sex linkage
X-chromosome longer than Y-chromosome, so most genes on X chromosome not present on Y chromosome =SEX LINKED GENE -Women have two copies of this gene (2 X chromosomes) -Men have only 1 copy (1 X and 1 Y chromosome) -3 possible genotypes for females -2 possible genotypes for males
Tissues involved in transport in plants
Xylem tissue Phloem tissue
What is the oxidation state of an element?
Zero - in both diatomic and singular form.
Why is Zn not a transition metal?
Zn can only form a +2 ion. In this ion the Zn2+ has a complete d orbital and so does not meet the criteria of having an incomplete d orbital in one of its compounds.
Substance made when [Cr(H2O)6]3+ reacts with dil. NH3 (Formula, colour, state)
[Cr(H2O)3(OH)3] Grey-Green, Ppt,
Substance made when [Cr(H2O)6]3+ reacts with dil. NaOH (Formula, colour, state)
[Cr(H2O)3(OH)3] Grey-Green, Ppt,
Formula of Cr3+ metal aqua ion in soln
[Cr(H2O)6]3+
Substance made when [Cr(H2O)6]3+ reacts with XS NH3 (Formula, colour, state)
[Cr(NH3)6]3+ Purple, Soln,
Co-ordinate bond
a covalent bond in which both electrons are donated by one atom
What are the main forms an ore takes
an oxide or a sulphide
The right side of the heart pumps....
deoxygenated blood to the lungs
Advantages of using Ethene to produce ethanol
faster, purer, continuous (cheaper)
Measuring the rate of reaction of magnesium
if not cleaned properly both Mg and MgO will react with acid at different rates. Mg + 2HCL →MgCL2 + H2 MgO + 2HCL → MgCl2 + H2O
BaSO4
least soluble barium meal given to patients to absorb x rys reacts with sulphuric acid - slow reaction BaSO4 covers metal and prevents further reduction Ba + H2SO4 →BaSO4 Sulphate Test - unknown compound + BaCl2 + HCl - white precipitate of BaSO4 ( Ba2+ + SO4 2- →BaSO4(s) )
Advantages of Copper Extraction using scrap iron
less energy used, lower grade ores (more sustainable), lower quality scrap iron (not wasted)
What is the equation linking the number of moles to concentration and volume?
number of moles = concentration x volume (in dm3)
Thrombocytes
platelets
Belt transect procedure
• Place quadrat at regular intervals along the line. • Record abundance of species within the quadrat. Data from belt transect can be plotted as a set of bar charts or as a kite diagram.
Electrode potential
A list of electrode potential written in order from the most negative to positive.
Phagocytes
Ingest and digest pathogens or infected cells. 1. Neutrophils 2. Monocytes -> Macrophages
ATP produced from reduced NAD
2.5
pH
= - log [H^+]
Transect
A line along which samples are taken, either by noting the species at equal distances (line transect) or placing quadrats at regular intervals (belt transect). Used to find out distribution of species across an area. Can lay out measuring tape in a straight line to represent transect
Allele
A particular variety of a gene
Gene
A sequence of DNA nucleotides coding for a polypeptide/protein, that forms part of a DNA molecule.
Gene
A sequence of DNA nucleotides that code for a specific polypeptide or protein.
What is the test for Aldehydes?
Add Tollen's reagent to the sample and heat. A silver mirror indicates the presence of an aldehyde. Add Fehling's solution to the sample and heat. A brick-red precipitate indicates the presence of an aldehyde. [These are both mild oxidising agents, which oxidise the Aldehydes.]
What is the test for Haloalkanes?
Add aqueous sodium hydroxide to the sample and heat. Add dilute nitric acid and aqueous silver nitrate. A white precipitate soluble in ammonia indicates that a chloroalkane was present. A cream precipitate soluble in concentrated ammonia indicates a bromoalkane was present. A yellow precipitate insoluble in ammonia indicates that an iodoalkane was present.
Where does gaseous exchange occur in humans
Alveoli
Lewis base
An electron pair donor.
Respiratory substrate
Any biological molecule that can be broken down in respiration to release energy
Stimulus
Any change in the internal or external environment
Effect of enzyme concentration on rate of reaction when there are more than enough enzymes to deal with available substrate
Any further increase in enzyme concentration has no effect on the rate of reaction
Respiratory substrate
Any substance that can be broken down in respiration to release energy. -Cells respire glucose, but they can also respire other carbohydrates, lipids and proteins.
Which coordination system is used for thermoregulation?
Autonomic nervous system
Haemoglobonic acid (HHb)
Combination of H+ and Hb
Why is control of pH important?
Blood pH too high or too low (highly acidic or alkaline) enzymes become denatured as hydrogen bonds that hold them in 3D shape affected so shape of active site changes and no longer works.
Oxyhaemoglobin (HbO8)
Combination of Hb and O2
Coronary arteries
Blood vessels that supply the heart muscle with oxygen-rich blood
Colour of Cu2+ metal aqua ion in solution
Blue
Substance made when [Co(H2O)6]2+ reacts with conc. HCl
Blue Soln [CoCl4]2-
Colour of Cr3+ metal aqua solution
Blue-Green
Reflex action
Body's response to a stimulus without making a conscious decision to respond Fast automatic response
Why do people crack hydrocarbons?
Because the light fractions such as petrol and naptha are in higher demand so have a higher value. In order to meet this demand, the less valuable, heavier hydrocarbons are broken into smaller hydrocarbons (including alkenes).
Which ones contain platelets (blood, tissue fluid, lymph)
Blood Only in tissue fluid if capillaries are damaged
Which ones contain dissolved solutes (blood, tissue fluid, lymph)
Blood Tissue fluid Lymph
Which ones contain water (blood, tissue fluid, lymph)
Blood Tissue fluid Lymph
How does adrenaline activate glycogenolysis?
Both adrenaline and glucagon can activate glycogenolysis inside a cell. 1. Adrenaline/glucagon bind to receptors in cell surface membrane of liver cells. 2. This activates adenylate cyclase. 3. Activated adenylate cyclase converts ATP into chemical signal called second messenger = cyclic AMP (cAMP) 4. cAMP activates cascade (chain of reactions) that break down glycogen to glucose.
Colour of Fe3+ metal aqua ion in soln
Brown
Which plants, C4 or C3, have enzymes with higher optimum temperatures?
C4
What cooridnates musuclar movement
CNS Receives sensory information and decides what kind of response is needed. If response needed is movement, CNS sends signal along neurones to tell skeletal muscles to contract.
Why do plants have a low RQ value?
CO2 released in respiration is used for photosynthesis (so not measured)
Another name for the light independent reaction
Calvin cycle
Number of strands in RNA and DNA in viruses
Can be either 1 or 2 for either DNA or RNA
Catalyst
Changes the rate of a chemical reaction without being chemically altered at the end of the reaction
Which type of characteristics do environmental factors affect?
Characteristics showing continuous variation
COPD
Chronic obstructive pulmonary disease. Group of diseases that involve permanent airflow reduction. 1. Emphysema 2. Chronic bronchitis
Write an equation for the reaction between chlorine and cold, dilute aqueous sodium hydroxide. Give two uses of the resulting solution
Cl2 + NaOH → NaClO + NaCl + H2O, bleach, disinfectant
Types of enzyme inhibition
Competitive and non-competitive inhibition
Gene pool
Complete range of alleles present in a population
Location of glycolysis
Cytoplasm
Why are muscle fibres striated?
Due to alternating dark and light bands caused by thick and thin myofilaments
Alleles
Different forms of a gene
Why is a reflex action very fast?
Does not involve making conscious decision to respond
Why is glycolysis considered an anaerobic process?
Doesn't require oxygen to occur.
Nucleophile
Electron pair donor
Oxidative phosphorylation description
Energy carried by electrons from reduced coenzymes, is used to make ATP. Involves the electron transport chain and chemiosmosis.
ATP
Energy carrying molecule
ΔE
Energy difference between d-orbitals
Enthalpy of Hydration
Enthalpy change when 1 mol of gaseous ions is converted into aqueous ions
Types of glands
Exocrine glands Endocrine glands
Disadvantages of using Hydrogen for extraction
Explosive, difficult to store, expensive
Substance made when [Fe(H2O)6]2+ reacts with sodium carbonate
FeCO3 Green Ppt
What would you observe when Group 2 metals react with cold water?
Fizzing (more vigourously down the group). Dissolving metal (faster down the group). Solution heating up (more down the group). White precipitate appearing with Calcium (less precipitate down the group).
What is used to form lipids (using products of calvin cycle)
GP: Fatty acids TP: glycerol
What controls cell growth and division
Genes
Which hormones activate glycogenesis, glycogenolysis and gluconeogenesis?
Glycogenolysis: Glucagon Gluconeogenesis: Glucagon Glycogenesis: Insulin
Chlorine + Water in Sunlight
H+, Cl- and O2 are produced, green Cl2 fades as it reacts to form O2 (colourless)
Disproportionation of Chlorine + Water
HClO and HCl are produced, universal indicator is red then bleached white
Allele frequency
How often an allele occurs in a population
Example of dominant genetic disorder
Huntington's
What are the Alternatives to CFCs?
Hydrofluorocarbons have stronger bonding, so are less likely to produce fluorine radicals.
What is incomplete combustion?
If there's not enough oxygen, hydrocarbons cannot combust incompletely and you get a particulate carbon soot and carbon monoxide gas as well as carbon dioxide. This is bad because carbon monoxide gas is poisonous.
Colour of Iodine and Iodide
I2 → Grey solid, purple gas I- → Brown solution, black solid
When can injections of antibodies be useful
INSTANT IMMUNITY: When aid worker travels to an environment where risk of disease is high.
What is complete combustion?
If you burn (oxidise) alkanes with plenty of oxygen, you get carbon dioxide and water
What factors affect the colour of a transition metal?
Identity of metal Oxidation state of metal Identity of ligands Co-ordination number
What reaction would occur between Mg and warm water?
If Mg is reacted with warm water, Magnesium Hydroxide will be produced. This is must slower and has no flame.
Autoimmune disease
Immune system sometime fails to distinguish between self and non-self. 1. Our body cells contain self antigens = proteins that identify us to our immune system. 2. When our T cells mature in the thymus we make T cells that have receptor sites. 3. T cells that have receptor sites that bind to our ow self antigens are destroyed. 4. Autoimmune disease = some of the T cells are not destroyed. 5. So some of the T cells can be activated by your own self antigens to stimulate an immune response where by antibodies and T killer cells attack parts of you own body.
heterogeneous
In a different state from reactants
Where is cholera most likely to occur
In places where people use food or water that has been in contact with untreated sewage, as the bacteria is present in the faeces of an infected person.
How are B or T cells activated
In response to the presence of a non-self antigen.
Saltatory conduction
In a myelinated neurone, local circuits cannot be set up in the parts of the neurone where the myelin sheath is present as it is an electrical insulator. Depolarisation can only occur at the nodes of Ranvier (where sodium ions can get through the membrane) Neurone's cytoplasm conducts enough electrical charge to depolarise the next node so nerve impulses jump from one node of Ranvier to the next. This greatly increases speed at which action potential travels along axon. In a non-myelinated neurone, the impulse travels as a wave along the whole length of the axon membrane = slower.
What is a dative covalent bond?
In dative covalent, also known as co-ordinate bonding, one atom proved both of the shared electron in the bond.
Passive artificial immunity
Injection of antibodies obtained from another animal cells.
Location of oxidative phosphorylation
Inner mitochondrial membrane / cristae
Why can't the neurone cell membrane be excited straight after an action potential?
Ion channels are recovering and can't be made to open.
What are Ions?
Ion have different numbers of protons and electrons. Negative ions have more electrons than protons and positive ions have fewer electrons than protons.
A change in PH affects ______ ______
Ionic bonds
What happens if Barium metal is reacted with Sulphuric acid? How is this similar to other Group 2 metals/acids?
It will react slowly as the insoluble Barium Sulphate produced will cover the surface of the metal and act as a barrier from further reaction. The same effect will happen to a lesser extent with metals going up the group as the solubility increases. The same effect does not happen with other acids (Hydrochloric and Nitric) as they form soluble group 2 salts.
Gene
Length of DNA that codes for a particular protein or polypeptide
Other than the rate of photosynthesis, what else does light, temperature and CO2 affect?
Levels of GP, RuBP and TP in the calvin cycle
What to stages can photosynthesis be split into?
Light dependent reaction Light independent reaction
Where is glucose converted to glycogen
Liver
Lewis Acid
Lone Pair Acceptor
Lewis Base
Lone pair donor
Chromosomes
Long thread like structures each made up one long molecule of DNA
What reactions occur between Group 2 metals and steam?
Magnesium burns in steam to produce Magnesium oxide and Hydrogen. A bright white flame is produced.
Magnesium + Water
Magnesium burns in steam to produce MgO and H2 white flame Mg(s) + H2O(g) → MgO(s) + H2(g) Magnesium reacts with warm water to produce Mg(OH)2 and H2 Mg(s) + 2H2O(l) → Mg(OH)2 + H2 slower, no flame
Activation energy
Minimum energy required for the reaction to occur
Xylem
Nonliving vascular tissue that carries water and minerals ions from the roots of a plant to all other parts.
Why can't oxidative phosphorylation occur in the absence of oxygen?
Nothing to accept the electrons and protons at the end of the electron transport chain.
Heart rate
Number of heart beats per minute
What is the equation used to calculate the number of moles of any substance?
Number of moles = mass(g)/ mass of one mole (mol)
What is recorded in blood tests for people that are HIV positive
Number of specific T cells
What affects the most probably energy?
Only a change in temperature; which increases the most probably energy and therefore increases the number of molecules above the activation energy.
Cyclic photophosphorylation
Only uses PS1 Electrons from chlorophyll molecule of PSI aren't passed onto NADP, but are passed onto electron carriers and back to PSI. So electrons are recycled and can repeatedly flow through PSI. -No NADP (electron not transferred to NADP) or O2 produced. -ATP produced via photophosphorylation as electrons move along ETC
How do we calculate Percentage Atom Economy?
PAE = Mr of desire product/Molecular mass of reactants)x100
What cells does the cortex consist of
Parenchyma cells Collenchyma cells
What are the male gametes in plants called?
Pollen grains
Secondary structure
Polypeptide chain does not remain flat and straight: 1. Hydrogen bonds form between amino acids in the chain. 2. This makes the chain coil into an alpha-helix or fold into a beta-bleated sheet.
What solution is used to absorb CO2 in a respirometer
Potassium hydroxide solution
How does mutation of a gene affect the tertiary structure of a protein
Primary structure of a protein is determined by a gene. Mutation in gene, means a different amino acid is slotted in the sequence = different bonds formed = protein folds in a different way = different 3D structure formed
Histone proteins
Proteins around which DNA molecules are wound around and help to support the DNA
Transcription factors
Proteins that bind to a specific DNA sequence and control the flow of information form DNA to RNA by controlling the formation of mRNA.
What are electron carriers?
Proteins that transfer electrons
Cause of malaria
Protoctist: Plasmodium - Several species, which cause different types of malaria. - In a person the plasmodium infects the red blood cells and breeds inside of them. - Toxins are released when the Plasmodium bursts out of the cells, causing fever
Bronsted-Lowry Base
Proton Acceptor
Bronsted-Lowry Acid
Proton Donor
Bronsted Lowry base
Proton acceptor
When can random sampling/systematic sampling be used?
Random sampling: When there is no pattern in the distribution of the population for example. Systematic sampling: Used to investigate how species distribution
Equilibrium
Rate of forwards reaction equals rate of reverse reaction and no net change in the concentration of reactants and products
Buffer solution
Resists change in pH for the addition of small amounts of acid or base. (It is also able to maintain its pH upon dilution with water).
Explain the Melting and Boiling point of Cl2 (g), S8 (s) and P4 (s):
Simple Molecular molecules have weak van der Waals between them, so little energy is needed to break them, meaning they have low melting and boiling points. S8 has a higher Melting point than P4 because it has more electrons (128 as oppose to 60) so has stronger van der Waals between molecules.
Nucleolus
Site of ribosome synthesis
What is the particle structure in solids liquids and gases?
Solids - Its particles are very close together giving it a high density and making it incompressible. The particles vibrate about s fixed point with no free movement Liquids - Have a similar density to a solid with free moving particles allowing it to flow Gas - the particles have a high amount of energy and are much further apart. Particles have free movement with little attraction between them.
Group 2 Sulphates
Solubility decreases down the group ppt formation equations are: XCl2 + Na2SO4 → 2NaCl + XSO4(s) or X2+ + SO4 2- → XSO4(s)
The triplet code is degenerate (explanation)
Some amino acids are coded for by more than one base triplet. There are twenty amino acids, but since there are 4 bases, there are 64 different combinations of bases in a triplet.
What is used to form proteins (using products of calvin cycle)
Some amino acids are made from glycerate-3-phosphate, which are joined together to form proteins
What is the solubility of the covalent bonds like?
Some simple covalent compounds dissolve in water depending on how polarised the molecules are
What type of cells are the walls of alveoli and capillaries made of
Squamous epithelium cells
Where do all the specialised cells originally come from
Stem cells
Homeostatic control flow chart
Stimulus Receptors Central control. Effector Response
Template strand
The DNA strand that is used in protein synthesis
What is a Metallic Bond?
The Electrostatic attraction between Cations and delocalised electrons.
Hess's Law
The Enthalpy Change for a chemical reaction is independent of the route taken
Tertiary structure
The coiled or folded chain of amino acids is coiled and folded further, as more bonds form between different parts of the polypeptide chains. (This is the final 3D structure for proteins made of single polypeptide chain)
Carbamino haemoglobin
The combination of carbon dioxide and haemoglobin. (Carbon dioxide doesn't bind to haem group so Hb can still carry O2/H+)
State the source of the energy for the extraction of iron in a blast furnace
The combustion of coke, air is blown in C + O2 → CO2 CO2 + C → 2CO
Gene pool
The complete range of alleles present in an population
What is an empirical formula?
The empirical formula gives the smallest whole number ratio of atoms in a compound.
What is the First Ionisation Energy?
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions. X(g) ---> X+ (g) + e-
Bond dissociation enthalpy
The enthalpy change when one mole of covalent bonds are broken in the gas phase
Allopatric speciation
The formation of a new species due to reduced gene flow between two populations as a result of geographic isolation
What is the trend of First Ionisation Energy down group 2?
The outermost electrons are held more weakly because they are successively further from the nucleus in additional shells, meaning they are more shielded from the attraction of the nucleus by the repulsive force of the inner shell electrons.
Tertiary structure definition
The overall three-dimensional shape of a polypeptide due to the interactions between parts of the polypeptide chain such as hydrogen bonding, formation of disulfide bonds, ionic interactions and hydrophobic interactions.
What is Redox?
The oxidation and reduction occurring simultaneously.
Why has vaccination failed to eradicate cholera?
The pathogen is found in the lumen of the gut
Cardiac cycle definition
The period between the start of one heartbeat and the beginning of the next
Habitat definition
The place where a species lives within an ecosystem
Habitat
The place where a species lives within an ecosystem.
What is the General Formula?
The simplest algebraic formula for a member of an Homologous Series.
Give the steps for extracting Titanium:
TiO2 (solid) is converted to TiCl4 (liquid) at 900'c. The TiCl4 is purified by fractional distillation in an Ar atmosphere, which is inert so won't react with air (oxygen). The Ti is displaced and is extracted by Mg in an Ar atmosphere at 500'c.
Retention Time
Time taken for a particular substance to pass through a chromatography column
Why do muscle fibres need many nuclei?
To aid production of the many different proteins.
Roles of receptors
Transform energy from stimulus into energy of an action potential (electrical energy) in a sensory neurone. Receptor - type of energy received Rod and cone cells in retina - light Pacinian corpuscles in skin - pressure Temperature receptors in skin - heat Taste and smell receptors in tongue and nose - chemical potential energy in molecules Hair cells in cochlea in ear - Sound energy
Phloem transport is biderctional
Translocation can occur in either direction in the phloem
Movement of water from roots to leaves
Transpiration stream
What is Termination three of Methane?
Two methyl radicals react to form Ethene.
Ozone and CFCs
UV radiation breaks C-Cl bons in CFCs, so Cl free radicals are in the upper atmosphere and catalyse ozone decomposition into O2 molecules
What conditions are needed for (alcohol solvent) elimination by OH?
Under reflux conditions at a high temperature, with ethanolic NaOH (dissolved in Ethanol). An Alkene is produced.
Use of poly(propene)
Utensils, Containers, Rope, Carpet Fibre, Stiff
Active artificial immunity
VACCINATION: Involves introducing attenuated pathogens into the body. - The lymphocytes are activated by the antigens, so stimulating the production of antibodies and memory cells against the pathogens without causing illness.Wh
What is VSEPR (valence-shell electron-pair repulsion theory?
VSEPR states that lone pair-lone pair repulsion is greater than lone pair-bond pair repulsion, which is greater than bond pair-bond pair repulsion. As a result of this, the greatest angles in the shape are between lone pairs of electrons. Bond angles between bonded pairs are often reduced because they are pushed together by lone pair repulsion.
Enveloped virus
Virus which possesses a phospholipid bilayer derived from host cell
Cause of measles
Virus: Morbillivirus
Cause of smallpox
Virus: Variola
Examples of pathogens
Viruses Bacteria Fungi Protoctists
Unlike phagocytes, lymphocytes....
act against specific pathogens. Each lymphocyte contains a set of genes that code for the production of a particular type of receptor.
Monosaccharides in sucrose
alpha-glucose fructose
Monosaccharides in lactose
beta-glucose galactose
Substance made when [Cu(H20)6]2+ reacts with conc. Ammonia.
blue ppt redissolves [Cu(NH3)4(H20)2]2+
Magnesium + Oxygen
burns with a white flame to produce a white solid with high melting point (ionic). Magnesium also reacts slowly with oxygen even without the flame, so a thin layer of MgO is always on Mg ribbon and needs to be cleaned off by emery paper
Disadvantages of Electrolysis
electricity costs, low purity achieved
Racemic Mixture
equal mixture of enantiomers
Conditions for Nucleophillic Substitution to produce amines
excess conc. NH3 in ethanol under pressure
Transpiration occurs as a result of...
gas exchange
Reactions of group 2 with oxygen
group 2 metals burn in oxygen
Disadvantages of using Ethene to produce ethanol
high tech equipment needed, non-renewable, high energy costs to high pressure
Unidentate ligands
ligands which form one co-ordinate bond to a metal ion
Bidentate ligands
ligands which form two co-ordinate bonds to a metal ion.
Sieve tube elements are joined end to end to form....
sieve tubes
What are permanent dipole-dipole forces?
these are the weak electrostatic forces that occur between polar molecules.
Why aren't mean bond enthalpy values very accurate?
they are averaged over a range of compounds
What are the 5 stages in mass spectrometery?
vaporisation, ionisation, acceleration, deflection, and detection
They xylem contains tubes called....
vessels, which are made out of dead cells called xylem vessel elements
Water is drawn into the roots down a...
water potential gradient
Conditions for the fermentation of Glucose
yeast anaerobic conditions - air would cause ethanol to be oxidised to produce ethanoic acid 30-40 degrees (optimum of 38) - if too low slow reaction, if too high, enzyme denaturation
Why does transcription occur
Organelles for protein synthesis (ribosomes) are found in the cytoplasm. DNA is too large to move out of the nucleus, so a section is copied into RNA.
Function of histone proteins
Organise the DNA into tightly coiled structures during mitosis.
Refractory period
Period of time during which neurone is recovering from an action potential, and during which another action potential cannot be generated. (i.e. time taken between end of depolarisation and resting potential)
Protein allowing passage of galactose into E.coli cell
Permease
Neutrophil
Phagocyte
Where are phagocytes produced
Phagocytes are produced in the in the bone marrow by mitotic division of stem cells which develop into monocytes and neutrophils.
Sacrcomere
Part of myofibril between to Z discs
Organism's interface with the environment
Pathogens get into the body through an organism's surface of contact with the environment. 1. Skin 2. Digestive system 3. Gas-exchange system
Reflex arc
Pathway along which impulses are transmitted from a receptor to an effector without involving conscious regions of the brain.
The response of phagocytes is non-specific
Phagocytes can act against any invading organisms.
Process by which macrophages engulf pathogens
Phagocytosis (to phagocytose)
What is the substance PEP found in C4 plants?
Phosphoenolpyruvate (3C)
Negative feedback
Process in which a change in some parameter, such as blood glucose level, brings about processes which move its level back towards normal again. (i.e. keeps things around the normal level)
What is the reason for genetic diversity between populations of the same species?
Populations may be adapted slightly differently to the different areas they are in
What are Positional isomers?
Positional isomers are a type of structural isomer. They have the same skeleton and the same atoms or groups attached but the group of atoms are attached to a different carbon atom.
Order of Reaction
Power of concentration term (in rate equation)
Order of reaction with respect to.....
Power to which the concentration of a particular species is raised in the rate equation
Linkage
Presence of two genes on the same chromosome, so that they tend to be inherited together and don't assort independently
How does penicillin inhibit the growth of bacteria
Prevents growing bacteria from forming the bacterial cell wall, which gives the cell structure and support.
What haloalkanes tend towards different mechanisms
Primary Haloalkanes - substitutions Secondary Haloalkanes - Both Tertiary Haloalkanes - Elimination
What do Primary and Secondary alcohols become once oxidised?
Primary alcohols can be oxidised to form aldehydes. Secondary alcohols are oxidised to form ketones. Tertiary alcohols cannot be oxidised.
Bonds in primary structure
Primary structure is held by peptide bonds (covalent bonds) between amino acids
Stem cells in the bone marrow
Stem cells in the bone marrow divide and differentiate to replace worn out blood cells e.g. erythrocytes, neutrophils
Distillation
Technique that separates organic product from reacting mixture - used for the oxidation of primary alcohols to aldehydes
Lattice enthalpy of dissociation
The enthalpy change when one mole of a solid ionic compound is broken up into its constituent elements in the gas phase
Lattice enthalpy of formation
The enthalpy change when one mole of a solid ionic compound is formed from its constituent elements in the gas phase
Enthalpy of solution
The enthalpy change when one mole of a solid ionic substance is dissolved in enough water so that the ions are separated and do not interact with each other
Enthalpy of formation
The enthalpy change when one mole of a substance is formed from its elements, with all substances in their standard states under standard conditions
2nd ionisation enthalpy
The enthalpy change when one mole of gaseous +1 ions loses one electron per ion to form one mole of gaseous +2 ions
2nd electron affinity enthalpy
The enthalpy change when one mole of gaseous 1- ions gains one electron per ion to form one mole of gaseous 2- ions
Enthalpy of hydration
The enthalpy change when one mole of gaseous atoms are dissolved in water
1st electron affinity enthalpy
The enthalpy change when one mole of gaseous atoms gains one electron per atom to form one mole of gaseous 1- ions
Enthalpy of atomisation
The enthalpy change when one mole of gaseous atoms is formed from an element in its standard state
1st ionisation enthalpy
The enthalpy change when one mole of gaseous atoms loses one electron per atom to form one mole of gaseous +1 ions
Enthalpy of combustion
The enthalpy change when one mole of substance goes under complete combustion in oxygen, with all substances in their standard states
What is oxidation?
The loss of electrons. The gain of oxygen. The loss of Hydrogen. Increase in oxidation state.
Glycogen
The main energy storage material in animals. (Animals get energy from glucose too, but the store excess glucose as glycogen)
What is Molar mass?
The mass of a substance containing the same number of elementary particles are there are in 12.000 grams of Carbon-12.
What is molar mass?
The mass of one mole of something, the same as relative molecular mass but the units are g mol-1
Vmax
The maximum rate of reaction when all the enzyme active sites are filled
What is Mean Bond Enthalpy?
The mean bond enthalpy is the enthalpy needed to break 1 mole of covalent bonds measured in the gaseous state averaged across many compounds containing the bond. The mean bond enthalpy has a positive value for the endothermic process of breaking 1 mole of a covalent bond, but a negative value for the exothermic process.
Cell signalling
The method by which cells communicate with each other
Ionisation Enthalpy
The minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state.
Activation Energy
The minimum energy required for a chemical reaction to take place Ea
Activation energy
The minimum energy that needs to be supplied before the reaction will start
What is Activation Energy?
The minimum energy which particles need to collide with to start a reaction.
What is the molecular formula?
The molecular formula gives the actual numbers of atoms in a molecule.
Carbaminohaemoglobin
The molecule resulting from combination of carbon dioxide and haemoglobin.
How does nuclear charge affect ioniation energy?
The more protons that are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons
Which are the best oxidising agents?
The most electronegative elements - such as Fluorine. The oxidising power of the Halogens decreases down Group 7.
Chemiosmosis
The movement of H+ ions across a membrane, which generates ATP. (Electrical potential energy of protons used)
Mass flow
The movement of a fluid in response to a pressure gradient, from an area of high pressure to an area of low pressure
Active transport
The movement of particles from an area of low concentration to an area of high concentration that uses energy provided by ATP.
Transpiration stream
The movement of water from roots to leaves.
Chiasma
The point where genetic material is exchanged between two non-sister chromatids during crossing over
Locus
The position at which a particular gene is found a particular chromosome; same gene always fround at the same locus
Why is glucose/sucrose the form in which carbohydrates are transported around an organism
They are soluble
What are reducing agents?
They are species which bring about reduction by being oxidised and losing electrons.
What are oxidising agents?
They are substances which bring about oxidation by being reduced and therefore gaining electrons.
What is the general trend of Group 2 Sulphates?
They become less soluble down the group, with BaSO4 being the least soluble.
What is the trend in solubility of Group 2 Hydroxides?
They become more soluble down the group. All insoluble hydroxides appear as white precipitates.
How do hormones bring about changes in a cell?
They bind with the receptors on target cells which activates intracellular signaling molecules which acts as a second messenger to transfer signal throughout cell
Why are viruses called parasitic
They can only reproduce by infecting and taking over living cells
Why are monosaccharides soluble in water
They contain OH groups allowing them to form hydrogen bonds with water
Why can viruses only replicate inside other living cells
They don't possess their own machinery for genome replication, transcription and translation
Why are Transition metals good Catalysts?
They have a vacant 3D orbital, which makes a good catalyst.
What happens when a person his heterozygous for the gene coding for the B-globin polypeptide (gentoype HbAHbS)?
They have one allele of the B-globin gene in each cell coding for the production of normal B-globin, and one coding for the production of the sickle cell B-globin. Half of the person's haemoglobin will be normal and half will be sickle cell hemoglobin. SICKLE CELL TRAIT Have enough normal haemoglobin so won't have problems .
What is the only reason viruses are considered as living organisms?
They have particles made up of proteins and nucleic acids which is common amongst all cellular organisms.
What is Steroisomerism?
When Isomers have the same molecular formula and the same structural formula but the arrangement of bonds in a 3D space is different.
Unidente
When a ligand can form only one coordinate bond in a complex ion.
Bidentate
When a ligand can form two co-ordinate bonds in a complex ion.
Multidente
When a ligand can form two or more coordinate bonds in a complex ion.
What is a Molecular or Parent ion?
When a molecule is ionised and one electron is removed, forming a free radical which is positively charged.
Active immunity
When a person's own lymphocyte makes the antibody
Autocatalysis
When a reaction is catalysed by one of the products.
What was found in Rutherford's gold foil experiment?
When alpha particles were fired at a thin gold sheet, most of them passed straight through with a very small number deflected straight back.
What is a neutralisation reaction?
When an acid reacts with an alkali and a salt and water is produced.
What is a Molecular Ion?
When an electron is knocked off an organic molecule to form a positive ion.
When is random sampling most suitable?
When area looks reasonably uniform or when there is no particular pattern in the distribution of species. AVOIDS BIAS
What is Chain Isomerism?
When compounds have the same molecular formula but a different arrangement of carbon atoms in the chain.
What is structural Isomerism?
When compounds have the same molecular formula but a different arrangement of covalent bonds (or atoms) in space.
What is Functional Isomerism?
When compounds have the same molecular formula but a different functional group, such as: Alkenes and CycloAlkanes Aldehydes and Ketones
What is Positional Isomerism?
When compounds have the same molecular formula but the functional group is in a different position.
During the test for Haloalkanes, why is the sample heated with sodium hydroxide?
When heated with dilute sodium hydroxide, a nucleophilic substitution reaction occurs and halide ions are produced.
What is artificial selection / selective breeding?
When humans select individuals in a population with desirable traits to breed so as to increase frequency of the desirable trait amongst the population.
Symptoms of chronic bronchitis
Coughing in order to remove mucus that has accumulated
Products when [Cr(OH)6]3- reacts with sodium hydroxide.
CrO4^2- + 3e- + 4H2O
What flame colour is Strontium?
Crimson
Substance made when [Cu(H20)6]2+ reacts with sodium carbonate
CuCO3 Green ppt
Effect of increase in CO2 on dissociation curve
Curve shifts down, showing that more oxygen is released from blood. (The lower the saturation of Hb with O2, the more O2 is released.
What are the two types of phosphorylation in the light dependent reaction?
Cylcic photophosphorylation Non-cyclic photophosphorylation
Discontinuous variation
DISCONTINUOUS VARIATION (qualitative variation) - two or more distinct categories i.e. each individual falls into only one of these categories, there are no intermediates. e.g. sex - either male or female. • Inherited characteristics that show discontinuous variation are usually influenced by only one gene (or small number of genes) - these characteristics = monogenic (characteristics controlled by only one gene) ○ E.g. Violet coloured flower (either coloured or white) controlled by only one gene.
Myosin dark and light bands
Dark bands = A-bands: Contain thick myosin filaments and some overlapping thin actin filaments. Light bands = I-bands: Contain thin actin filaments only
Xylem vessel elements
Dead cells that make up the xylem vessels
Why does deamination take place instead of direct excretion of amino acids?
Deamination allows energy from amino acids to be used by first converting the amino acids to organic acids which can then be respired.
Bohr effect
Decrease in affinity of hemoglobin for oxygen due to pH and partially to increase in PCO2
Give one reason why a reaction is very slow at room temperature
High Ea so few molecules have E>Ea, and low rate of successful collisions
Effect of high pO2 (in lungs) on saturation of haemoglobin with oxygen
High partial pressure =haemoglobin has high affinity for O2 =oxygen readily combines with Hb =Hb has high saturation of O2
What causes mass flow of blood through the blood vessels
High pressure produced by the heart beating
Effect of high/low temperature on cholesterol function
High temperature: Cholesterol molecules reduce membrane fluidity by preventing free movement of phospholipid molecules. Low temperature: Cholesterol molecules prevent close packing of phospholipids and slow solidification.
What conditions are needed for photo respiration
High temperatures High light intensities Present in low altitudes of tropical areas
Using Ethene to produce ethanol
High temperatures and pressures are required, conc. H3PO4 catalyst is needed,
Disadvantages of using Carbon for extraction
High temperatures, metal carbides formed sometimes
Homeostasis description
Homeostasis = maintenance of a constant internal environment. Involves control systems keeping internal environment roughly constant within certain limits.
What is the mechanism of Thermal cracking?
Homolytic Fission - where carbon-carbon bonds break and each carbon atom receives a free radical (electron).
Which coordination system is used to control blood glucose concentration?
Hormonal system
Concentration/Pressure Increase of causes:
More particles per unit volume, particles collide more frequently So more effective collisions. e.g. doubling conc, doubles the number of particles per unit volume and the frequency of effective collisions
Examples of 4C plants
Most tropical plants: Maize Sorghum plants Sugar cane
Translocation
Movement of dissolved substances (assimilates) in phloem tissue, to where they're needed.
Passive transport
Movement of ions and molecules down their concentration gradients without the expenditure of energy
Bulk transport
Movement of large quantities of material into or out of the cell. Endocytosis or exocytosis
Why do multicellular plants need transport systems
Multi cellular organism has small surface area to volume ratio. Plants need substances like water, minerals, sugar and also need to get rid of substances. Exchange of substances by diffusion would take too long. So plants need transport systems to move substances to and from individual cells quickly.
How did different alleles arise?
Mutation Mutation has caused different alleles to have slightly different base sequences.
Silent mutations
Mutation that has no apparent effect on an organism
Benefits of a narrow lumen in
Increased area of water in contact with wall = water molecules adhere to walls helping to prevent breakage of the column of water
Effect of temperature on transpiration rate
Increased temperature = increased rate. Increased temperature means the water molecules have more energy, so evaporate from cell walls in leaf more rapidly. This increases water potential gradient between air spaces inside leaf and air outside leaf, so water diffuses out of leaf more rapidly.
Reducing Strength of Halide ions
Increases down the group - more easily oxidised,
How does adrenaline get the body ready for action?
Increases glucose concentration - so making more glucose available for muscles to respire.
Melting Point down group 7
Increases, increased atomic radius (molecule size), larger vdws between molecules, as more e-, more energy needed to break the forces
What is the effect of Pressure on Equilibrium?
Increasing pressure will cause the equilibrium to shift towards the side with fewer moles of gas to oppose the change and thereby reduce the pressure. Decreasing pressure will cause the equilibrium to shift towards the side with more moles of gas to oppose the change and thereby increase the pressure. If the number of moles of gas is the same on both sides of the equation, then changing pressure will have no effect on the position of equilibrium.
What is the effect of Concentration on Equilibrium?
Increasing the concentration of eg. OH- ions causes the equilibrium to shift to oppose this and move in the direction of fewer OH- ions to remove or decrease the concentration.
Why is Titanium expensive?
Na/Mg cost, batch process (slower more labour intensive), Ar, Moisture removal (so TiCl4 isn't hydrolysed), high temperatures required
What occurs when cold Dilute Sodium Hydroxide and Chlorine react?
NaCl and NaClO are formed instead of HCl and HClO.
Why do lipids and proteins have an RQ value lower than one?
More oxygen is needed to oxidise fats and lipids than to oxidise carbohydrates.
Why is the RQ value less than 1 for lipids and proteins/amino acids?
More oxygen needed to respire them than carbohydrates
Explain why an increase in pressure at constant temperature increases the rate of reaction
More particles in a given volume so increased frequency of collisions
What reagent is used during Water solvent nucleophilic substitution?
NaOH / KOH dissolved in a water solvent, to provide aqueous OH-
Reagents required to form CrO4^2-
NaOH or H2O2
Disproportionation of Halogen + Sodium Hydroxide
NaX, NaXO, H2O are produced, mixture is used to bleach and kill bacteria (disinfectant)
DNA found in prokaryotic cells
Naked, circular DNA
How is the allele frequency changed in a population?
Natural selection - environment Genetic drift - Chance Founder effect Artificial selction
Ozone's effect on the atmosphere
Naturally occuring O3 layer in the upper atmosphere is beneficial - filters harmful UV radiation from the Sun O3 in the lower atm. is a pollutant and contriiibutes to smog formation
Transmission of nerve impulses
Neruones transmit electrical impulses very rapidly along the cell surface membrane from one end to another. Not flow of electrons. Signals are brief changes in the distribution of electrical charge across the cell surface membrane called action potentials, caused by the very rapid movement of sodium ions and potassium ions into and out of the axon.
Which communication system requires more energy?
Nervous system
How do receptors communicate with the effectors?
Nervous system or hormonal system
Diffusion
Net movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient
Methods by which antibodies inactivate pathogens
Neutralisation Agglutination
Examples of exothermic reactions
Neutralisation, Fuel Combustion, Carbohydrate Oxidation (used in respiration)
ATP componenets
Nitrogenous base adenine Ribose sugar 3x phosphate groups
Can prokaryotes undergo mitosis?
No
Does a sieve tube element have a nucleus?
No
Are viruses living
No - they are non-cellular structures
Substance made when [Fe(H2O)6]3+ reacts with sodium hydroxide in excess.
No Change
Substance made when [Co(H2O)6]2+ reacts with XS NaOH
No Change from dilute
How do the bundle sheath cells in C4 plants obtain CO2?
No air gets to these cells so obtain carbon dioxide from mesophyll cells in the form of malate.
Substance produced when Al3+ metal aqua ion reacts with NH3 in excess
No change
Change in pressure
No change in value of Kc
Carbon Neutrality of Ethanol
No net CO2 emissions into the atmosphere, due to photosynthesis of sugar crops which are used to produce glucose for fermentation
When does depolarisation start?
Once threshold potential is reached (-55mV) Depolarisation and repolarisation makes up the action potential
Half cell
One half of an electrochemical cell.
What is a Mole?
One mole of a substance is the mass in grams that contains the Avogradro constant of particles (6.02 x 10^23).
Allele
One of the different forms of a gene
Chromatid
One of two identical parts of a chromosome, held together by a cenetromere, formed during interphase by the replication of the DNA strand.
Which conditions effect the value of Kc?
Only temperature will effect the Kc.
Oogenesis process
Oogenesis similar to spermatogenesis but: -Much fewer gametes made than in spermatogenesis -Process takes longer with long waiting stages 1. Diploid cells divide by mitosis to produce many oogonia. 2. Oogonia being to divide by meiosis, but stop when they reach prophase I - called primary oocytes at this stage are still diploid. 3. All of this happens before baby girl is born, and at birth has around 400000 primary oocytes in ovaries. 4. When puberty reached some primary oocytes get a little further with their division by meiosis proceeding from prophase I to the end of the first meiotic division, forming two haploid cells. 5. However division is uneven; one cell gets most of the cytoplasm, and becomes a secondary oocyte. 6. While the other is little more than a nucleus - polar body. 7. Polar body simply way to get rid of half the chromosomes and has no further role to play in reproduction. Each month one secondary oocyte is released into the oviduct form one of the ovaries. If it is fertilised, it continues its division by meiosis, and can now be called an ovum.
Translocation moves substances from....
sources to sinks
Where are elastic fibres found in the trachea, bronchus
Connective tissue
Rate constant (k)
Constant of proportionality in the rate equation
Reduction
Gain of electrons
Oxidising Agent
Gains electrons
What part of the brain aids in thermoregulation?
Hypothalamus
Substance made when [Co(H2O)6]2+ reacts with XS NH3
Pale Brown Sol [Co(NH3)6]2+
What colour is Chlorine water?
Pale Green.
Colour of F2
Pale yellow Gas
Dehydrogenation
Removal of hydrogen from a molecule
What is excretion?
Removal of unwanted products of metabolism
Decreasing temperature
Shifts the equilibrium in the exothermic direction
What does a high RQ value indicate? (greater than 1)
Shortage of oxygen causing anaerobic respiration to occur as well as aerobic.
What are the uses of CFCs/HFCs?
Shorter chains are used as Aerosols, Propellants and for refrigeration. Longer chains are used as degreasing agents or dry cleaning agents.
Maxwell- Boltzmann Distribution
Shows the spread of energies that molecules of gas or liquid have at a particular temperature
Reducing agent
Something that donates electrons and gets oxidised.
Quadrat
Square frame that marks off an area of ground, or water, where you can identify the different species present and/or take a measurement of their abundance.
Where does the light dependent reaction take place?
Thylakoid membrane
Why is TiO2 converted to TiCl4 before extraction?
TiCl4 is molecular (TiO2 is ionic), so it can be purified by fractional distillation (liquid at rt)
What is a Polar Bond?
"The existence of partial positive and negative charges on each end of the bond as a result of the unequal sharing of electrons." In a covalent bond between two atoms which have a small electronegativity difference, the electron pair is not equally shared but displaced more towards the more electronegative atom. For example, H+Cl-.
What is the formula for Atom economy?
% atom economy = mass of desired product / total mass of reactants x 100
General formula of carbohydrates
(CH2O)n
Abnormal form of haemoglobin
(HbS) Sickle cell haemoglobin
ATP produced in respiration
(Stage -> Molecules produced -> Number of ATP molecules) 1. Glycolysis -> 2 ATP 2. Glycolysis -> 2 NADH -> 5 ATP 3. Link reaction (x2) -> 2 NADH -> 5 ATP 4. Krebs cycle (x2) -> 2 ATP 5. Krebs cycle (x2) -> 6 NADH -> 15 ATP 6. Krebs cycle (x2) -> 2 FADH2 -> 3 ATP TOTAL = 32
Anaerobic respiration features
*No oxygen *Only glycolysis occurs *Two types - alcoholic fermentation and lactate fermentation *Both produce two ATP per molecule of glucose
Tar
- A mixture of substances including various chemicals that act as carcinogens. - These can make epithelial cells lining the lungs mutate, which leads to a malignant tumour.
How can a person be immune to disease
- A person is immune to a disease if the pathogens causing the disease are unable to reproduce in the body and cause illness. - This happens when the body already contains or is able to rapidly produce large quantities of antibodies against the antigens associated with the particular pathogen.
What happens to myofibril bands when the sarcomeres contract?
- A-bands stay same length - I-band gets shorter - H-zone gets shorter - Sarcomere itself gets shorter
How does temperature affect the levels of levels of GP, RuBP and TP in the calvin cycle
- All the reactions in the calvin cycle are catalysed by enzymes (e.g. rubisco) - At low temperatures, all of the reactions will be slower as the enzymes work more slowly. - So levels will fall. - Levels affected the same way at high temperatures as enzymes start to denature
Why is thermoregulation important?
- Body temperature too high = enzymes may become denatured. Enzyme molecules vibrate too much, breaking the hydrogen bonds that hold them in their 3D shape. Shape of enzyme's active site is changed and no longer works as a catalyst = metabolic reactions less efficient. - Body temperature too low = enzyme activity reduced, slowing rate of metabolic reactions - Optimum temperature = highest rate of enzyme activity
Carbon monoxide
- Combines irreversibly with haemoglobin, to form carboxyhaemoglobin. - This reduces the amount of haemoglobin available to combine with oxygen, so reducing the amount of oxygen that is transported to body tissue.
T helper cell
- Coordinates immune response - When a pathogen is detected, they secrete cytokines which act as a chemical signal. - This stimulates the T and B-lymphocytes, resulting in the mass production of specific B and T cells.
How do pathogens get into the body through the gas-exchange system
- If you breathe in air that contains pathogens, most of them will be trapped in mucus lining the lung epithelium. - The epithelial cells have cilia which beat and move mucus up the trachea to the mouth, where its removed. - But some pathogens still reach the alveoli and invade cells, causing disease.
How do pathogens get into the body through the digestive system
- If you eat or drink food that contains pathogens, most of them will be killed by the acidic conditions of the stomach. - However some may survive, and pass into the intestine where they can invade cells of the gut wall and cause disease.
How does light intensity affect the levels of levels of GP, RuBP and TP in the calvin cycle
- In low light intensities the products of the light-dependent stage (reduced NADP and ATP) will be in short supply. - So conversion of GP to TP and RuBP is slow. - So levels of GP will rise and levels of TP and RuBP will fall
Cells involved in non-specific immune response
- Neutrophils - Macrophages - Natural killer cells
Function of telomeres
- Prevent ends of chromosomes form joining other ones. - Prevent the ends of the chromosomes from breaking down. - Protect the integrity of the genetic material/prevent loss of genes, allowing continual replication.
T killer cells
- These cells recognise infected cells (non-self protein produced by pathogen) and tumour cells. - They destroy them by secreting enzymes/hydrogen peroxide which rupture their membranes, causing the cell to lyse.
Memory cells
- These circulate in the blood after pathogen has been removed. - If stimulated, they divide and rapidly produce a secondary immune response.
Adaptations of storage polysaccharides
-Branched structure = quick release of glucose -Coiling = compact -Large molecule = stores lots of energy -Insoluble = water won't enter cell by osmosis - good for storage
Le Chatelier's principle
A system at equilibrium reacts to oppose a change in conditions
Fatty acid components
Carboxly group Variable R group attached (variable hydrocarbon tail)
Which systems are affected by the smoke from cigarettes
Cardiovascular system Gas exchange system
How can glands be stimulated to secrete hormones?
-Change in concentration of a substance e.g. glucose concentration in blood -Electrical impulses
What are the 3 factors considered in Industrial Equilibria?
1) Yield of Product 2) Rate of Reaction 3) Cost of maintaining reaction conditions
Threshold potential
-55mV Action potentials are only generated if potential difference reaches value between -60 and -50mV. Less than this and action potential not generated.Re
Cancer
-A disease that can result from the mutation of a gene that normally controls cell division. -A tumour that invades surrounding tissue. -Abnormal cells divide without control and can invade nearby tissues.
Sickle cell anaemia features
-Abnormal haemoglobin molecules in area of low oxygen concentration = stick to each other = form big chain of molecules that is insoluble = form long fibres. -This pulls the red blood cells out of shape = making them sickle shaped instead of round. -Cannot move through blood system easily, and can get stuck in capillaries.
How does carbon dioxide concentration affect the levels of levels of GP, RuBP and TP in the calvin cycle
-At low CO2 concentration, conversion of RuBP to GP is slow (less CO2 to combine with RuBP) -Level of RuBP will rise as it's still being made, and levels of GP and TP will fall (as they're used up to make RuBP
Blood pressure in capillaries
-Blood pressure is lower than in arteries. -Total cross sectional area of the arteries is greater than that of the arteries that supply them.
What can cause a reduce in the surface area for gas exchange in the lungs?
-Emphysema: alveolar walls destroyed -Lung cancer:
Function of kidney
-Excrete waste products e.g. urea produced by liver -Regulate body's water content
Uses of mitosis
-Growth -Repairing damaged tissue (produce new cells to replace damaged ones) -Asexual reproduction (single parent gives rise to genetically identical offspring.)
Effect of competitive inhibitor concentration on enzyme activity
-How much the enzyme is inhibited depends on the relative concentrations of the inhibitor and substrate. -A high concentration of the inhibitor means nearly all the active sites will be taken up and hardly any of the substrate will get to the enzyme. -Increase in amount of substrate = decrease in effect of inhibitor
Effect of non-competitive inhibitor concentration on enzyme activity
-How much the enzyme is inhibited is independent of the relative concentrations of the substrate and enzymes. -So increasing the concentration of the substrate won't have any effect - enzyme activity is still inhibited.
Transmission of smallpox
-Inhalation of droplets of moisture containing the virus (variola) -Direct contact
Cell cycle phases
-Interphase (genetic material is copied and checked for any errors that may have occured during copying) -Mitosis -Cytokinesis
Why do large organisms need transport systems?
-Long way for diffusion, as centre of body long way from surface. -Surface area to volume ration is smaller.
How are capillaries adapted for efficient diffusion
-Many of them = large surface area -Walls are one cell thick -Very small -Very close to exchange tissues =SHORT DIFFUSION PATHWAY
How can mutations lead to changes in allele frequency?
-Mutations lead to formation of new alleles -If this new allele codes for traits that allow individual to have selective advantage against selective pressures - individuals more likely to reproduce and pass on allele.
Natural selection
-Occurs when allele codes for a characteristic that affects the organism's chances of survival. -Not all individuals are as likely to reproduce as each other due to variation in the alleles they have. -Individuals that have an allele that increases their chance of survival are more likely to reproduce and pass on their genes (including the beneficial allele), than individuals without the beneficial allele -So greater proportion of the next generation inherit the beneficial allele. -They in turn are more likely to survive, reproduce and pass on their genes. -So the frequency of the beneficial allele increases from generation to generation.
4 steps in an enzyme reaction
-Substrate + enzyme -Enzyme substrate complex -Enzyme product complex -Product + enzyme (free to take part in next reaction)
Blood pressure in arteries
-The blood is at a high pressure in the arteries as it has just been pumped from the heart. -The pressure oscillates in time with the heartbeats. -Due to the stretching and recoiling of the artery walls, the oscillations are smoothened. -Pressure becomes gradually steadier the further the blood moves along the arteries. -The mean pressure gradually decreases.
What is the taxonomic system for classifying viruses is based on?
-The diseases they cause - The type of nucleic acid they contain (DNA or RNA) - Whether the nucleic acid is single stranded or double stranded
Natural killer cells
-They patrol the blood and lymph. -Cells that display a protein/receptor that is a non-self molecule triggers the natural killer cells. -Secretes an enzyme which ruptures the membrane causing the cell to lyse (APOPTOSIS)
Why does the calvin cycle need six turns to make one hexose sugar?
-Three turns produces six molecules or TP as two molecules of TP are made for every one CO2 molecule used. -Five out of six of these TP molecules are used to regenerate RuBP. -So three turns of the cycle = only one TP produced that's used for hexose sugar. -Hexose sugar has six carbons, so two TP molecules needed for one hexose sugar. So cycle must turn six times to form two TP molecules - forming one hexose sugar.
Advantages of chloroplast movement within palisade cells
-To absorb more light -To prevent damage from high light intensitites
How are the steep concentration gradients of oxygen and carbon dioxide maintained across the gas exchange surface?
-Ventilation -Blood flow in capillary
Adaptation of xylem x4
-Vessel elements have no end walls -Lignified cell walls -Made up of dead cells that have no contents(cytoplasm) -Pits in cell walls
Effect of exposing plant cell to hypotonic solution
-Water potential outside cell is higher than inside. -Net movement of water is into the cell. -Cell starts to swell, but has no protective cell wall so it bursts. LYSIS
Effect of exposing plant cell to hypertonic solution
-Water potential outside cell is higher than inside. -Net movement of water out of the cell. -Cell shrinks. -Cell becomes crenated as the cytoplasm pulls away from cell membrane.
Effect of exposing animal cell to hypotonic solution
-Water potential outside cell is lower than inside. -Net movement of water is into cell. -The vacuole swells. -The vacuole and cytoplasm push against the cell wall = cell has become turgid
Effect of exposing animal cell to hypertonic solution
-Water potential outside cell is lower than inside. -Net movement of water out of the cell. -Cell becomes flaccid. -Cytoplasm and plasma membrane pull away from the cell wall (plasmolysis)
Possible main products when [Cr(H2O)6]3+ reacts with Zn or conc HCl. State the type of reaction and colours.
1) [Cr(H2O)6]2+ (aq) reduction, blue soln. 2) Cr2O7 (aq) reduction, orange soln.
Transcription definition
1.The process whereby an RNA copy is made of a gene. 2. The process whereby a template strand of DNA is used to make a strand of messenger RNA with a complementary sequence of bases.
How do you calculate mean bond enthalpy?
/\H = Sum of(Mean bond enthalpies of reactants) - Sum of(Mean bond enthalpies of products).
Wavelength of beam of electrons
0.4nm
Lipids (triglycerides) RQ
0.7
Proteins/amino acids RQ
0.9
Carbohydrate RQ
1
Components of triglycerid
1 Glycerol molecule 3 Fatty acids
Krebs cycle steps
1) *Acetyl CoA from the link reaction combines with oxaloacetate to form citrate. *Coenzyme CoA released to be used in the link reaction again. 2) *6C citrate, decarboxylation, CO2 removed, converting it to a 5C molecule. *Dehydrogenation - NAD picks up to form reduced NAD. 3) *5C compound converted to 4C - decarboxylation. *Dehydrogenation - produces 1 reduced FAD and 2 reduced NAD. *ATP produced by direct transfer of phosphate group from intermediate compound to ADP. (substrate level phosphorylation) *Citrate converted back into oxaloacetate.
Products of glycolysis
1) 2x reduced NAD - go to last stage, oxidative phosphorylation. 2) If oxygen available, 2 pyruvate molecules actively transported into matrix of mitochondria for link reaction.
Properties of ATP making it a good energy source
1) ATP stores or releases only a small, manageable amount of energy at a time, so no energy is wasted. 2) ATP soluble so easily transported. 3) Small, so easily transported. 4) Easily broken down, so energy easily released. 5) Can transfer energy to another molecule by transferring one of its phosphate groups. 6) ATP can't pass out of the cell, so the cell always has an immediate supply of energy.
Copper Extraction using scrap iron
1) Copper ores are reacted with H2SO4 2) Iron reduces and therefore displaces copper solid from solution
How are mitochondria adapted for respiration?
1) Inner membrane is folded into cristae, increasing membrane's surface area to maximise respiration. 2) Lots of ATP synthase molecules in inner membrane to produce lots of ATP in final stage. 3) Matrix contains all reactants and enzymes for Krebs cycle to occur.
Temperature Increase of a system causes:
1) More collision energy (K.E) so more molecules have E>Ea, so more successful collisions 2) Increased collision frequency increased collision energy accounts for around 95% of the increase in the rate of reaction
Dynamic Equilibrium
1) Rate of forwards and backwards reactions are equal 2) concentrations of reactants and products stays constant
Properties of Transition Metals
1) Variable oxidation states 2) Catalytic action 3) Coloured compounds 4) Formation of complexes
What proportion of the triose phosphate produced is used to form organic compounds e.g. glucose
1/6
Diameter of prokaryotic cells
1-5 micrometers
What causes branching in amylopectin
1-6 glycosidic bonds
Advantages of insulin produced by gene technology
1. -Insulin produced by genetically engineered E.coli is identical to human insulin as it is made using the genetic code on the human insulin gene. -Insulin obtained from pancreas of an animal is slightly different so may have different effects when used to treat diabetes. 2. -Large quantities of insulin can be made continuously using E.coli and this can be done under controlled conditions. -Only small quantities can be obtained from pancreas of an animal and not easy to purify the insulin to produce a standard product that is safe for medicinal use. 3. -Many religions and cultures, and also many individuals are uncomfortable with the idea of harvesting insulin from a dead animal for use in humans.
Non-cyclic photophosphorylation (full)
1. -Light energy is absorbed by PSII -The light energy excites electrons in chlorophyll -The electrons move to a higher energy level -These high-energy electrons move along the electron transport chain to PS1 2. -As the excited electrons from chlorophyll leave PSII to move along the electron transport chain, they must be replaced. -Photolysis occurs - water molecules split into oxygen and hydrogen atoms. -Each hydrogen loses electron to form proton. -The electrons are picked up by PSII to replace electrons they lost. -Oxygen diffuses out of chloroplast and into air. - H2O -> 2H+ + 1/2 O2 + 2e- 3. -The excited electrons lose energy as they move along the electron transport chain. -This energy is used to transport protons into the thylakoid so that the thylakoid has a higher concentration of protons than the stroma. This forms a proton gradient across the membrane. -Protons move down their concentration gradient, into the stroma, via an enzyme called ATP synthase. The energy from this movement combines ADP and Pi -> ATP.(PHOTOPHOSPHORYLATION) 4. -Light energy is absorbed by PSI, which excites the electrons again to an even higher energy level. -Finally, the electrons are transferred to NADO, along with a proton from the stroma, to form reduced NADP. 2H+ + 2e- + NADP -> Reduced NADP
DNA replication process
1. -The enzyme DNA helicase breaks the hydrogen bonds between the bases along part of the two strands. -Part of the molecule unzips to form two single strands, exposing the bases. 2. -Each original single strand acts as a template strand for a new strand. -Free floating DNA nucleotides join to the exposed bases on the orginal template strand using specific base pairing, by the formation of hydrogen bonds between the bases on the original strand and the nucleotides. 3. The nucleotides on the new strand are joined together by the enzyme DNA polymerase, by linking together the phosphate and deoxyribose groups of adjacent nucleotides. 4. Each new DNA molecule contains one strand from the original DNA molecule and one new strand.
Transcription process
1. -The hydrogen bonds between the bases along the two DNA strands in a gene. -The DNA molecule uncoils at this point, so the strands are separated, and the bases are exposed. 2. -One of the strands is used as a template strand to make an RNA copy called messenger RNA. -Free floating RNA nucleotides pair up with the exposed bases on the template strand using specific base pairing, by the formation of hydrogen bonds between the bases. 3. RNA polymerase links the RNA nucleotides, forming an mRNA molecule. 4. The mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome in the cytoplasm in preparation for translation. 5. When enough mRNA has been produced, the hydrogen bonds between the uncoiled strands of DNA re-form, and the strands coil back into a double helix.
How does CO2 concentration affect oxygen unloading
1. i) Most of the CO2 from respiring tissue diffuses into red blood cells and is converted into carbonic acid by the enzyme carbonic anhydrase, which catalyses the reaction between H2O and CO2. ii) Some CO2 diffuses into the blood plasma. iii) Some CO2 diffuses into the red blood cells, and attaches directly to the haemoglobin (doesn't bind to haem group, so Hb can still carry O2. 2. Carbonic acid then dissociates into hydrogen ions (H+) and hydrogencarbonate ions (HCO3-). 3. This increase in H+ causes oxyhaemoglobin to unload its oxygen (H+ displaces O2 from HbO8) so that haemoglobin can take up H+ ions, forming haemoglobinic acid (HHb). This means Hb mops up the H+ ions acting as a buffer, as it controls the pH of the blood. 4. The hydrogen carbonate ions diffuse out of the red blood cells and are transported in the blood plasma. 5. When the blood reaches the lungs the low pCO2/high pO2 causes the hydrogen ions and hydrogen carbonate to combine into CO2 which diffuses into the alveoli and is then breathed out.
Why does the oxygen dissociation curve have an 's' shape (1)
1. (Curve gets steeper) When Hb combines with the first O2 molecule it changes the shape of the Hb in a way that makes it easier for the other molecules to combine with it too. 2. (Curve becomes shallow again) As Hb gets more saturated, becomes harder for O2 molecules to join. 3. Steep bit in the middle: Easy for O2 molecules to join Shallow bits at each end: Harder for more O2 molecules to join 4. When the curve is steep a small change in the pO2 causes a big change in the amount of O2 carried by the Hb.
Structure of anitibodies (5)
1. 4 polypeptide chains: - 2 heavy - 2 light 2. The 4 polypeptide chains are joined together by mainly disulfide bonds to form a Y-shaped molecule. 3. Disulfide bonds - Strong covalent bonds between the cysteine amino acids. 4. The variable regions are found at the ends of the arms = antigen binding sites. 5. The variable regions differ between antibodies so each antibody specific to one type of antigen.
Infectious disease
1. A disease that can be passed between one person and another. 2. Caused by pathogens (usually microorganisms such as viruses, bacteria, fungi, protoctists)
Non-infectious disease
1. A disease that cannot be passed between one person and another. 2. Not caused by pathogen. 3. Examples : lung cancer, sickle cell anaemia
Exocytosis
1. A vesicle is produced containing the material to be removed from the cell. 2. The vesicle moves towards the cell surface membrane. 3. The membrane of the vesicle and the cell surface membrane join and fuse. 4. The contents of the vesicle is released outside the cell.
Muscle contraction process
1. ACTION POTENTIAL TRIGGERS INFLUX OF CALCIUM IONS i) When an action potential from a motor neurone stimulates a muscle cell, it depolarises the sarcolemma. Depolarisation spreads down T-tubles to sarcoplasmic reticulum. ii) This causes sarcoplasmic reticulum to release stored Ca2+ ions into sarcoplasm. iii) Calcium ions bind to troponin, causing it to change shape. This pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament. iv) This exposes the binding site, which allows the myosin head to bind. v) The bond formed between myosin head and actin filament = ACTIN FILAMENT CROSS BRIDGE 2. ATP PROVIDES THE ENERGY NEEDED TO MOVE THE MYOSIN HEAD... i) Calcium ions also activate enzyme ATPase, which breaks down ATP to provide energy. ii) The energy released from ATP moves the myosin head, which pulls the actin filament along in a rowing action towards centre of sarcomere - causing contraction (shortening) 3. ...AND TO BREAK THE CROSS BRIDGE i) ATP also provides energy to break actin-myosin cross bridge. ATP binds with head, one phosphate broken off, energy released. Energy used to break actin-myosin cross bridge so myosin head detaches from actin filament after it's moved. ii) Myosin head reattaches to different binding site further along actin filament and new actin-myosin cross bridge formed and cycle is repeated. iii) Many cross bridges form and break very rapidly, pulling the actin filament along - which shortens the sarcomere, causing muscle contraction. iv) Cycle will continue as long as calcium ions present and bound to troponin.
Adaptations of leaf structure
1. Absence of chloroplasts in epidermal cells: Allows light to pass through and reach palisade cells. 2. Waxy cuticle: Reduces evaporation of water from upper surface of leaves. 3. Palisade cells close to upper surface: Palisade cells contain most chloroplasts - Close to surface = sunlight easily reaches cells 4. Palisade cells tightly packed: Maximum absorption of light 5. Spongy mesophyll cells have large air spaces in between them: Easy and rapid diffusion of CO2 from stomata to chloroplasts in spongy and palisade layer. 6. Guard cells forming stomata: Can become turgid (open) or flaccid (closed) - control gas exchange 7. Leaves are thin and broad: Thin = sunlight can pass through all the palisade/spongy cells. Broad shape = greater surface area for absorption of sunlight and CO2. 8. Vascular bundles contain xylem vessels and phloem sieve tubes: Xylem - provides mechanical support for the leaf and brings water to the leaf Phloem - Take away assimilates e.g. sucrose, made by photosynthesis
Passage of water into the xylem
1. Absorbed into the root by moving down a water potential gradient from the soil into the root hair cells. 2. Cortex (symplast and apoplast pathways) 3. Endodermis 4. Xylem
Transmission of action potentials
1. Action potential at any point in axon's cell surface membrane triggers action potential in membrane on either side of it. 2. Depolarisation of one part of membrane (site of action potential) sets up local circuits between depolarised regions and resting regions on either side. 3. These local circuits cause depolarisation of these regions as well, generating action potentials in them as well. 4. So action potential transmitted along neurone as a wave of depolaristaion.
How do action potentials carry information?
1. Action potentials do not change in size as they travel, nor do they change in size according to the intensity of the stimulus. -No matter how long axon, peak value (+30mV) maintained all the way along 2. Speed of transmission of action potential remains constant in any one axon and is not dependent on the size of stimulus. 3. Frequency of action potential determined by intensity of stimulus i.e. strong stimulus = rapid succession of action potentials Weak stimulus = fewer action potentials per second. 4. Stronger the stimulus the more neurones stimulated.
How does adrenaline increase glucose concentration?
1. Adrenaline binds to receptors in the cell surface membranes of liver cells: -activates glycogenolysis -inhibits glycogenesis 2. Activates glucagon secretion and inhibits insulin secretion.
Why do athletes train in high altitudes
1. After some time in high altitudes their red blood cell count increases. 2. So when they return to low altitudes, their respiring cells can be supplied with oxygen at a faster rate as there are more red blood cells.
How is resting potential maintained
1. Aided by sodium-potassium pumps and potassium ion channels. -Sodium potassium pumps use active transport to move three sodium ions out of neurone for every two potassium ions moved in. (ATP needed) -Potassium ion channel = facilitated diffusion of potassium ions out of the neurone, down their concentration gradient. 2. Sodium-potassium pumps move 3 Na+ out of axon for every 2 K+ moved into axon via active transport - electrochemical gradients formed for each ion across the axon membrane. 3. Membrane has protein channels for potassium and sodium (open at all times) Far more potassium ion channels, so membrane more permeable to K+ - so they diffuse out of axon through potassium ion channel down electrochemical gradient. So potassium diffuses back out again much faster than sodium diffuses back in. 4. Inside of axon overall negative charge due to organic anions (e.g. glucose, amino acids) that cannot cross membrane to go outside. Outside more postivie ions, so inside of axon negatively charged compared with outside. 5. Potential difference across axon membrane = resting potential (-70mV)
Trachea
1. Air enters lungs by trachea. 2. Surrounded by layer of smooth muscle and regular C-shaped rings of cartilage. 3. Rings are incomplete to allow food to pass down the oesophagus easily.
Prevention and control of HIV
1. All blood to be used in transfusion should be screened to ensure it doesn't contain HIV. 2. All hypodermic needles should be sterile and used only once, and disposed of carefully. 3. Avoid use of drugs, as this prevents sharing of needles. 4. Avoid unprotected sexual activity (with anyone whose HIV status is unknown) 5. If diagnosed with HIV, sexual contacts should be traced and informed of the possibility of having the virus. 6. People should be educated on the matter. 7. HIV positive mother passing HIV to fetus is reduced if mother is treated with drugs.
Effect of pH on enzyme activity
1. All enzymes have an optimum pH value (e.g. pepsin = 2) 2. Above and below optimum pH, H+ and OH- ions found in acids and alkalis can affect the ionic bonds and hydrogen bonds that hold the enzyme's tertiary structure in place. 3. This makes active site change shape, so enzyme is denatured.
Transmission of HIV
1. Blood from infected person entering that of another: - sharing of hypodermic needles - blood transufsions 2. Unprotected sexual intercouse = exchange of fluids from penis, vagina or anus 3. From mother: - across the placenta to the fetus - from breast milk
Myasthenia gravis
1. All over body = neuromuscular junctions which connect nerve cells to muscle cells. 2. At these junction nervous system switches from electrical impulses to chemical messenger (acetylcholine) which stimulate muscular contractions. 3. ACETYLCHOLINE = messenger molecule: Released from neurones and binds to the receptors on the muscle cell which trigger a muscular contraction.
Control of blood glucose concentration when too high
1. Alpha and beta cells of islets of langerhans act as receptors. 2. After meal consisting of glucose - absorbed through small intestine and into blood stream. 3. As blood flows through pancreas the alpha and beta cells detect the rise in glucose concentration. - a cells > stop glucagon secretion - B cells > secrete insulin into blood plasma 4. Insulin carried around body via circulatory system. (CELL SIGNALLING) 5. Insulin = signalling molecule, protein so cannot pass through cell surface membrane to stimulate mechanism so binds to receptor in cell surface membrane of liver, muscle and fat cells and affects cell indirectly through mediation of intracellular messengers.
Phospholipids
1. Amphipathic 2. Phosphate group, glycerol, 2 fatty acids 3. Phosphate group is polar as it has an electrical charge (-) = hydrophilic
Neutralisation by antibodies
1. Antibodies bind to the antigens on the pathogen's membrane. 2. This prevents the antigens from attaching to the host cells (receptors on plasma membrane). 3. This prevents the pathogen from invading/entering the host cell. 4. The antibodies encourage macrophages to attack the pathogen.
Agglutination by antibodies
1. Antibodies bind to the antigens on the surface of several pathogens, joining them together. 2. This prevents them from entering the host cells. 3. The macrophages can then recognise and easily destroy the pathogen by phagocytosis.
Treatment for HIV
1. Antiretroviral therapy: Can increase the length of time between a person getting infected with HIV and developing symptoms of AIDS, significantly helping to prolong life. 2. Check T-lymphocyte cell count
Arterioles
1. Arteries branch into smaller vessels called arterioles. 2. These then form a network throughout the body. 3. They have smooth muscles in their walls, which can contract and make the lumen smaller, in order to direct blood to different areas of demand.
Features of arteries
1. Arteries carry blood from the heart to the rest of the body. 2. Blood is carried under high pressure. 2. Thick, muscular walls (smooth muscle) with elastic tissue = expand and recoil 3. Narrow lumen - maintain high pressure 4. Folded endothelium allowing expansion to cope with high pressure. 5. All arteries carry oxygenated blood except for the pulmonary arteries, which take deoxygenated blood to the lungs.
Differences between natural selection and artificial selection
1. Artificial selection is faster. 2. Organisms that reproduce selected for by humans in artificial selection but natural selection selection by environment. 3. Artificial selection aims for a predetermined result, but natural selection result is unpredictable. 4. Natural selection makes the species better adapted to environment, but artificial selection makes species more useful for humans.
Adhesion
1. As well as being attracted to each other, water molecules are attracted to the walls of the xylem vessels. 2. This helps water to rise up through the xylem vessels.
Adaptation to high altitude
1. At high altitudes the air is less dense, so pO2 is lower than at sea level. So Hb less saturated with O2 in lungs, and delivers less oxygen to body tissue. 2. After some time in high altitude, number of red blood cells increases = more Hb per unit volume. So even though Hb carries less oxygen molecules on average than at sea level, there are more Hb molecules in total, so same amount of oxygen being supplied to respiring tissue.
Translocation process
1. At the source, sucrose is actively loaded into the companion cells by active transport using energy from ATP. 2. This increases the concentration of sucrose in the companion cells, so it moves by diffusion down a concentration gradient into the phloem sieve tube through the plasmodesmata. 3. Increased concentration of sucrose, lowers the water potential (water potential gradient between sieve tube element and surrounding cells increased). Water enters tubes by osmosis. 4. This creates a high pressure inside the sieve tubes at the source end of the phloem. 5. At the sink end, sucrose diffuses out of the sieve tube element down a concentration gradient into a cell that is using sucrose. 6. This increases the water potential inside the sieve tubes (water potential gradient created), so water also leaves the tubes by osmosis. 7. This lowers the pressure inside the sieve tubes at the source end. 8. The result is a pressure gradient from the source end to the sink end. Phloem sap therefore moves by mass flow down this pressure gradient, through the sieve elements and through the sieve pores from the source to the sink
Ways in which lactic acid is broken down in animals
1. Cells can convert the lactic acid back to pyruvate. 2. Liver cells can convert the lactic acid back to glucose.
Ventricles contract, atria relax (Ventricular systole)
1. Atria relax. 2. Muscle in the walls of the ventricles contracts, decreasing the volume of the ventricles, increasing the pressure in the ventricles. 3. Pressure in the ventricles becomes higher than in the atria, forcing the AV valves shut to prevent back flow. 4. Pressure in the ventricles is also higher than in the aorta and pulmonary artery, forcing the semi-lunar valves open. 5. As the ventricle contracts, blood is forced out of the ventricles into these arteries.
Prevention and control of TB
1. Avoid over-populated areas 2. Maintain good care of the immune system. 3. Skin testing (before leaving country and before coming back) 4. Use of respiratory protective equipment. 5. Vaccination (BCG) 6. Treatment of HIV with drug therapy reduces the risk of an HIV-positive person getting TB.
Benefits of random sampling
1. Avoids any bias 2. Provides data that is representative of the whole area being surveyed
Lymphocyte features
1. B- and T-lymphocytes are both made in the bone marrow. 2. B-lymphocytes mature in the bone marrow, then spread through the body, some settling in lymph nodes, and some circulating in the blood. 3. T-lymphocytes collect in the thymus gland, where they mature before spreading into the same areas as the B-lymphocytes. 4. Both of them have large rounded nuclei, that take up most of the cell. 5. During maturation process, any lymphocytes that produce receptors that would bind with those on the body's own cells are destroyed. So remaining lymphocytes only act against non self molecules, such as those on the surface of pathogens (antigens).
Effects of base substitution/addition/deletion
1. BASE ADDITION/DELETION: -Have very significant effect on the structure, so the function of the polypeptide the allele codes for. -They alter every set of three bases that follows them in the DNA molecule. -Causes frame shifts in the code -Effects so large that protein is made useless or complete protein is never made as stop triplet introduced part way. 2. BASE SUBSTITUTION: -Often silent mutations as amino acids have more than one triplet code (i.e. triplet code is degenerate) So even if one base is changed the same amino acid is coded for. -HOWEVER can have large effects if stop triplet is coded for half way through gene.
Structure of nephron (check page 306 textbook)
1. BOWMAN'S CAPSULE = cup shaped structure at one side which surrounds tight network of capillaries = GLOMERULUS. Glomerului and capsules found in CORTEX. -Each glomerulus supplied with branch of renal artery = AFFERENT ARTERIOLE -Capillaries rejoin to form EFFERENT ARTERIOLE -Efferent arteriole leads off to form network of capillaries running closely along side rest of nephron. -Blood from these capillaries flow into branch of renal vein. 2. Tube then runs towards centre of kidney: -first forming twisted region = PROXIMAL CONVOLUTED TUBULE -long hairpin loop in medulla = LOOP OF HENLE 3. Tubule runs back up to cortex: -forms another twisted region = DISTAL CONVOLUTED TUBULE -finally joins COLLECTING DUCT -> Leads down the medulla and into the pelvis of kidney.
Bacterial resistance to antibiotics by mutation
1. Bacteria contain DNA, which contain genes coding for different proteins. 2. The proteins determine the organism's different characteristics. 3. A mutation is the change in the base sequence of an organism's DNA. 4. If a mutation occurs in an organism's gene = different protein produced = different characteristic 5. Some mutations may lead to a change in the sequence of bases = formation of gene that codes for a particular protein that provides protection against the antibiotic.
Mode of action of penicillin
1. Bacterial cell walls are made of peptidoglycan. 2. These are long molecules of peptides and sugars held together by cross links that form between them. 3. Penicillin inhibits the enzymes that are needed to make the cross links between the polymers. 4. This prevents the cell from growing properly and weakens the cell wall. 5. Therefore if water enters the cell by osmosis, the weakened cell wall cannot withstand the increase in pressure causing the bursting of the cell (lysis)
What are the three ways by which the sequence of bases in a gene can be altered during gene mutation?
1. Base substitution: One base simply takes the place of another; for example, CCT GAG GAG may change to CCT GTG GAG. 2. Base addition: One or more extra bases are added to the sequence; for example, CCT GAG GAG may change to CCA TGA GGA G. 3. Base deletion: One or more bases are lost from the sequence; for example, CCT GAG GAG may change to CCG AGG AG.
Enzymes
1. Biological catalysts = speeds up reactions by lowering activation energy 2. Globular proteins = soluble 3. Can be extracellular, working outside cells which produce them (e.g. amylase, pepsin) 4. Can be intracellular, working within cell (e.g. DNA polymerase) 5. Active site = substrate specifity 6. Work best at optimum temperatures and pHs 7. Highly specific due to tertiary structure
Overview of how blood is filtered in kidney
1. Blood enters kidney through renal artery and then passes through capillaries in the cortex of the kidneys. 2. ULTRAFILTRATION - As the blood passes through the capillaries, substances are filtered out of the blood and into long tubules (NEPHRON) that surround the capillaries. 3. SELECTIVE REABSORPTION - Useful subsstances are reabsorbed back into the blood from tubules in the medulla. 4. Remaining unwanted substances (e.g. urea) pass along the tubules, then along the ureter to the bladder, where they're expelled as urine. 5. Filtered blood passes out of the kidneys through the renal artery.
Mode of action of enzymes
1. Enzyme + substrate 2. Enzyme-substrate complex (lowers activation energy) 3. Enzyme-product complex 4. Enzyme + product
Where does the CO2 produced by respiring cells go
1. Blood plasma 2. Red blood cell: i) forms carbonic acid (carbonic anhydrase) ii) attaches directly onto haemoglobin molecules to form carbaminohaemoglobin. CO2 does not bind to haem groups, so the Hb is still able to pick up O2 or H+
How white blood cells leave the blood
1. Body cells at site of infection secrete histamines. 2. This increases the permeability of the capillary walls. 3. The phagocytes then move out of the capillary through the gap between the epithelial cells.
How is body temperature in mammals controlled?
1. Body temperature in mammals maintained at constant level by part of brain called HYPOTHALAMUS 2. Hypothalamus receives information about temperature from thermoreceptors: -thermoreceptors in skin detect external temperature (skin temperature) -thermoreceptors in hypothalamus detect internal temperature (blood temperature) 3. Thermoreceptors send impulses along sensory neurones to hypothalamus, which sends impulses along motor neurones to effectors (muscles and glands). [neurones part of autonomic nervous system, so all done unconsciously] 4. Effectors respond to restore the body temperature back to normal. (i.e. body temperature maintenance mechanisms: -adrenal glands -sweat glands -pili erector muscles -smooth muscles in arterioles)
How do the muscles work to bend the elbow1/
1. Bones of lower arm attached to bicep and tricep muscles by tendons. 2. Bicep and triceps = antagonistic pairs - work together to move bone (one contracts and other relaxes) 3. When bicep contracts, triceps relaxes. This pulls bone so arm bends at elbow. -Muscle that bends joint when contracted = flexor 4. When tricep contracts, biceps relaxes. This pulss bone so arm straightens at the elbow. -Muscle that straightens joint when contracts = extenosor
Similarities between natural selection and artificial selection
1. Both change the allele frequencies in the next generation - the alleles that code for the beneficial/desirable characteristic will become more common in the next generation. 2. Both may make us of random mutations when they occur - if a random mutation produces an allele that gives a beneficial/desirable phenotype, it will be selected for in the next generation.
Passage of inhaled air
1. Breath in = air enters trachea. 2. Trachea splits into two bronchi, one bronchus leading to each lung. 3. Each bronchus then branches off into smaller tubes called bronchioles. 4. The bronchioles end in small 'air sacs' called alveoli (where gass are exchanged)
Bronchioles
1. Bronchus divides into bronchioles. 2. First divides into terminal bronchioles then respiratory bronchioles.
Ways in which conditions can be controlled in glasshouses to increase crop yields
1. Burn propane to increase CO2 concentration 2. Add heaters to increase temperature 3. Add coolers to decrease temperature 4. Add lamps to provide light during the night
Components of trachea
1. C-shaped cartilage 2. Smooth muscle 3. Elastic fibres 4. Goblet cells 5. Ciliated epithelium
Calvin Cycle
1. CARBON FIXATION - CO2 enters the leaf through the stomata and diffuses into the stroma. -CO2 combines with ribulose bisphosphate (RuBP) a 5-carbon compound. This gives an unstable 6-carbon compound which quickly breaks down into tow molecules of (3C) compound = glycerate 3-phosphate. -Ribulose bisphosphate carboxylase (rubisco) catalyses the reaction between CO2 and ribulose bisphosphate. 2. REDUCTION -GP then converted to triose phosphate (TP) using energy from ATP and hydrogen from reduced NADP (products of light dependent reaction) -Triose phosphate is then converted into many useful organic compounds. 3. REGENERATION -Five out of every six molecules of TP produced in the cycle aren't used to make hexose sugars, but to regenerate RuBP -Regenerating RuBP uses the rest of the ATP produced by the light-dependent reaction.
Benefits of using light microscope over electron microscope
1. Can use living specimen (EM only dead) 2. Image formed is coloured (EM only black and white)
Why can't the phosphorylated glucose diffuse out of the cell into the surrounding tissue fluid?
1. Cannot pass through phospholipid bilayer. 2. Too big to fit through glucose protein channel. 3. No specific transport protein. 4. Used up as soon as it is made.
Main steps of the calvin cycle
1. Carbon dioxide is combined with ribulose bisphosphate to form two molecules of glycerate-3-phosphate. 2. ATP and reduced NADP are required for the reduction of GP to triose phosphate 3. Ribulose bisphospahte is regenerated
Effect of carbon monoxide on the cardiovasculour system
1. Carbon monoxide combines irreversible with haemoglobin, to form carboxyhaemoglobin. 2. This reduces the amount of haemoglobin available to combine with oxygen. 3. So reduces the amount of oxygen transported to body tissue. 4. Less oxygen will be supplied to the heart muscle as well, putting a strain on it when heart rate increases. e.g. during exercise 5. Also damages linings of arteries.
Cardiac muscle description
1. Cardiac muscle is myogenic - contracts on its own. 2. Found in walls of heart.
Function of glycoproteins in plasma membrane
1. Cell recognition: Cells from a particular individual or particular tissue have their own set of proteins and glycoproteins on their outer surface. 2. Cell signalling: Act as receptor molecules for substances such as hormones which bind with them; this can affect activity of the cell.
Structures found in plant cells but not animal cells
1. Cell wall 2. Large permanent vacuole 3. Chloroplasts
Break down of of lactic acid in animals
1. Cells can convert the lactic acid back to pyruvate (which re-enters respiration process) 2. Liver cells can convert the lactic acid back to glucose - to be respired or stored (glycogen)
How is photo respiration in C4 plants
1. Cells containing RuBP and rubisco are arranged around vascular bundles ( to keep away from high [O2]) -> forming bundle sheath cells 2. CO2 absorbed by mesophyll cells 3. PEP carboxylase catalyses CO2 + PEP (3C0 (phosphoenolpyruvate) -> oxaloacetate 4. Oxaloacetate converted to malate and passed onto bundle sheat cells. 5. CO2 removed from malate and reacted with RuBP with help of rubisco. 6. Light independent reaction proceeds as normal
Result of mutation
1. Changes sequence of bases in DNA. 2. So change in the sequence of amino acids in a protein occurs. 3. This in turn affects the 3D structure of the protein, so affecting its properties and function.
Function of integral and peripheral proteins in plasma membrane
1. Channel proteins: Provide hydrophilic channels that allow hydrophilic substances (ions and polar molecules) to pass through the membrane. The channels can be opened or closed to control substances' movement. 2. Carrier proteins: Actively transport substances across the plasma membrane against their concentration gradient, using energy derived from ATP. 3. Cell recognition 4. Cell signalling
Description of different types of photosynthetic pigments
1. Chlorophyll a: Mostly absorbs blue and red - appears yellow green Emits electron when it absorbs light energy 2. Chlorophyll b: Not as abundant as chlorophyll a 3. Carotenoids: -Accessory pigments -Orange pigments that protect chlorophyll from damage by formation of single oxygen atom (free radicals) -Also absorb wavelengths of light that chlorophyll cannot absorb and pass on some of the energy from light to chlorophyll. 4. Xantophylls: Also accessory pigments capturing form wavelengths of light not absorbed by chlorophyll and transferring this energy
Examples of infections diseases
1. Cholera 2. Malaria 3. HIV/AIDS 4. Measles 5. Tuberculosis 6. Small pox
Prophase
1. Chromosomes condense (shorter and fatter) 2. The pair of centrioles start moving to opposite ends of the cell. 3. The spindle begins to form. 4. Nuclear envelope breaks down. 5. Nucleolus disappears.
Chronic bronchitis
1. Chronic bronchitis is the inflammation of the lungs (linings of air passages). 2. Various components of cigarette smoke including tar, cause goblet cells to increase mucus production (due to irritation) and damages cilia making them beat less strongly. 3. The mucus accumulates, partially blocking the alveoli, making gas exchange more difficult, as the diffusion distance between the air in the alveoli and the blood in the capillaries greater. 4. Microorganisms also multiply in the mucus and cause lung infections that lead to inflammation, which decreases gas exchange. 5. The mucus build up stimulates persistent coughing, which can damage the tissues in the walls of the airways, making them stiffer and the airways narrower.
Lung cancer
1. Cigarette smoke contains tar which is made up of many carcinogens. 2. These carcinogens may cause mutations in the DNA of lung cells, which could lead to uncontrolled cell growth and formation of a malignant (cancerous) tumour. 3. Malignant tumours grow uncontrollably blocking air flow. 4. This decreases gas exchange and leads to a shortness of breath because the body struggles to take in enough oxygen. 5. The tumour uses lots of nutrients and energy to grow, which can cause weight loss.
Components of airways
1. Ciliated epithelium 2. Goblet cells (mucous glands) 3. Smooth muscle 4. Cartilage 5. Elastic fibres
Causes of extinction
1. Climate change 2. Competition 3. Habitat loss 4. Killing by humans
Interactions between alleles at the same locus
1. Codominant alleles in flower colour in snapdragons 2. Dominant and recessive alleles in tomato stem colour 3. Multiple alleles in the inheritances of the ABO blood groups
Products of Krebs cycle
1. Coenzyme A - reused in link reaction. 2. Oxaloacetate - regenerated for use in next Krebs cycle 3. 2 CO2 - released as waste product 4. 1 ATP - used for energy 5. 3 reduced NAD - to oxidative phosphorylation 6. 1 reduced FAD - to oxidative phosphorylation
Mechanisms by which water moves from roots to leaves
1. Cohesion and tension 2. Adhesion 3. Root pressure
What makes starch good for storage
1. Coiled structure of amylose makes it a compact molecule, so can fit more in to a small space. 2. Amylopectin has side branches allowing glucose to be released more quickly. 3. Starch is insoluble in water, so does not interfere with water concentration of cell, so doesn't cause water to enter cells by osmosis. 4. Large molecule, so it can store lots of energy.
Competitive inhibition
1. Competitive inhibitor molecules have similar shape to substrate molecules. 2. They compete with substrate molecules to bind to the active site, but no reaction takes place. 3. Instead they block the active site, so no substrate molecules can fit in.
Structure of myofibrils
1. Contain bundles of thick and thin myofilaments that move past each other allowing muscle contraction: -thick myofilament = myosin -thin myofilament = actin (both proteins) 2. Myofibril made up of many short units - sarcomeres. Ends of each sarcomere marked with Z-line. 3. M-line: middle of each sarcomere - marks middle of myosin filament. 4. H-zone: part with only myosin filament. 5. A-band: Myosin + actin (includes h-zone) 6. I-band: Only actin
Problems with control of cholera
1. Cost issues 2. Poor communities are still getting water from polluted sources. 3. Hard to control pollution - dumping waste into open sea. 4. No fully effective vaccine available, only temporary immunity provided.
How are excess amino acids broken down in the liver and excreted?
1. DEAMINATION - nitrogen containing amino groups are removed from excess amino acids, forming ammonia and organic acids. [ amino acid -> ammonia + organic acid (keto acid)] 2. Organic acids can be: -respired to give ATP -converted to glucose, glycogen for storage or fat for storage. 3. Ammonia: Too toxic for direct excretion so combined with CO2 to form urea. [2NH3 + CO2 -> CO(NH2)2 {urea} + H2O] Urea is released from liver into blood. Kidneys filter blood and remove urea as urine which is then excreted from body.
Process of phagocytosis
1. DETECTION: The pathogen is identified as foreign due to non-self proteins, and the phagocyte sticks to microbe to its surface. 2. INGESTION: Endocytosis - the microbe is engulfed by the phagocyte wrapping pseudopods around it to form a vesicle. 3. PHAGOSOME FORMS: A phagosome (phagocytotic vesicle) is formed, which encloses the pathogen in a membrane. 4. FUSION WITH LYSOSOME: Phagosome fuses with a lysosome which contains digestive enzymes which catalyse the hydrolysis / digestion of the pathogen. DIGESTS: (name bonds) -peptidoglycan -murein -carbohydrates -lipids -nucleic acid (RNA / DNA) 5. DISCHARGE: Indigestible material is discharged from the phagocyte.
Xylem vessel element features
1. Dead 2. No end walls 3. No contents/cytoplasm 4. Cell wall has lignin as well as cellulose
Uses of genetic fingerprinting
1. Determining genetic relationship: The more bands on a genetic fingerprint that match , the more closely related two people are. 2. Determining genetic variability within a population
Problems with controlling TB
1. Difficult to control as people are free to move and choose. 2. Difficult to trace infected people in remote places. 3. Negligence to carry protective equipment. 4. HIV is so common amongst people, so easily contract TB. 5. Negligence to do skin testing. 6. Malnutrition, which leads to poor immune systems. 7. Lack of money to afford drugs for HIV drug therapy, vaccination, skin testing etc
Structures of the chloroplast
1. Double membrane = chloroplast envelope 2. Thylakoids - stacked up = grana 3. Grana linked together by bits of thylakoid membranes = lamellae 4. Thylakoid membranes contain photosynthetic pigments (chlorophyll a/b and carotenoids) which are attached to proteins. Primary / accessory pigments 5. Proteins + pigments = photosystem Pigments arranged in light harvesting clusters = photosystems 6. Photosystem I (absorb light best at 700nm) photosystem II (680nm) 7. Stroma - contains enzymes sugars and organic acids 8. Starch grains - carbohydrates produced during photosynthesis stored as starch grains in stroma
Problems with treatment of HIV
1. Drug resistance 2. Poorer areas not able to receive treatment with effective drugs due to economic reasons.
How can drugs affect the action of neurotransmitters at synapses?
1. Drugs may have same shape as neurotransmitters so mimic action at receptors. So more receptors are activated. 2. Some drugs block receptors so can't be activated by neurotransmitters. -Fewer receptors can be stimulated = muscle can't be contracted. 3. Some drugs inhibit enzyme that breaks down neurotransmitters. -so more neurotransitters in synaptic cleft to bind to receptors, constant stimulation of postsynaptic neurone/effector. 4. Some drugs stimulate release of neurotransmitter from presynaptic neurone so more receptors activated. 5. Some drugs inhibit release of neurotransmitters from presynaptic neurone so fewewr receptors activated.
Difference between exocrine and endocrine glands
1. EXOCRINE GLANDS -Secrete chemicals through ducts (tubes) into cavities or onto surface of body, e.g. sweat glands secrete sweat onto skin surface. -Usually secrete enzymes, e.g. digestive glands secrete digestive enzymes into gut 2. ENDOCRINE GLANDS -Secrete hormones directly into blood -Hormones = chemical messengers - take message from one cell to another. -Hormones secreted when endocrine gland's stimulated by a change in concentration of a substance or by nerve impulses
Alveoli features
1. Each alveolus is made of a single layer of thin, flat cells called squamous epithelial cells (alveolar epithelium) 2. The alveoli are surrounded by a network of capillaries, giving each alveolus its own blood supply. 3. Lined with surfactant fluid
Endocrine function of pancrease
1. Endocrine tissue in pancreas made of islets of langerhans ( made of groups of specialized cells in the pancreas that make and secrete hormones) 2. Islets of langerhans found in clusters around blood capillaries. 3. Islets of langerhans secrete hormones directly into blood 4. Islets of langerhans made up of: - Alpha cells = secrete glucagon - Beta cells = secrete insulin Glucagon and insulin help to control blood glucose concentration.
Function of synapses in body
1. Ensure action potentials only travel in one direction. 2. One neurone may have synapses with many other neurones - allowing interconnection of nerve pathways from different parts of body. 3. Synapses allow wide variety of responses by effectors. -Motor neurone may need to receive neurotransmitters form many different neurones forming synapses with it before action potential can be generated. -Some neurones produce neurotransmitter which reduce chance of action potential being generated. -Balance between these signals from all the different synapses determines whether or not an action potential is produced in motor neurone, so whether or not effector takes action.
Why is it important that daughter cells produced during mitotc cell cycle in humans are genetically identical
1. Ensures that the daughter cells have the same number of chromosomes as the parent cell. 2. The cell would be rejected if it is genetically different. 3. Immune system will remove genetically different cells.
Protein functions
1. Enzymes 2. Antibodies: Immune response, made of two heavy and two light polypeptide chains bonded. 3. Transport proteins: (contain hydrophobic and hydrophilic amino acids, causing protein to fold up and form a channel with hydrophilic passage allowing transport of ions etc.) 4. Structural proteins (collagen, keratin)
Cells in in the blood
1. Erythrocytes 2. Phagocytes 3. Lymphocytes (platelets - not cell, but cell fragments)
Selective breeding to increase milk yield from dairy cattle
1. Farmers select a female with very high milk yield and a male whose mother had a very high milk yield and breed them together. Alleles for high milk yield passed onto next generation 2. They select the offspring with the highest milk yields and breed them together. 3. This is continued over several generations until a very high milk yielding cow is produced. 4. Over many generations alleles conferring desired characteristics increase in frequency, whilst alleles conferring characteristic not desired decreases in frequency or entirely lost.
Rough endoplasmic reticulum
1. Folds and processes proteins made by ribosomes. 2. Covered in ribosomes 3. More extensive
Function of phospholipid molecules in plasma membrane
1. Forms the fluid bilayer = fundamental structure of the membrane. 2. Have hydrophobic tails, so prevents passage of hydrophilic substances e.g. polar molecules, ions 3. Act as a barrier to water-soluble substances.
Saturated lipids
1. Found in animal fats 2. Melt at relatively higher temperatures 3. Have saturated fatty acids, which don't have any double bonds between their carbon atoms (no kinks in hydrocarbon tail)
Stem cells in animals
1. Found in embryo: differentiate into the specialised cells needed for fetus development. 2. Found in adult tissues: differentiate into specialised cells that need to be replaced.
Unsaturated lipids
1. Found in plants (e.g. olive oil) 2. Melt at relatively lower temperatures 3. Have unsaturated fatty acids, which have double bonds between carbon atoms, causing chain to kink
What determines the strength of a stimuli?
1. Frequency of action potentials. 2. Number of neurones stimulated (carrying action potentials)
How can antibiotics be obtained
1. Fungi and other organisms 2. Synthesis in laboratory
Phases of interphase
1. GAP PHASE 1: New cell grows and new organelles and proteins are made (carries out normal functions) 2. SYNTHESIS: DNA replication occurs in preparation for mitosis (now double stranded DNA) 3. GAP PHASE 2: DNA is checked for any damage that may have occurred during replication. Repairs and damage/kills itself preventing mutations in DNA from being passed on.
What are the two forms of mutation?
1. GENE MUTATION: Change in the structure of a DNA molecule, producing a different allele of a gene. 2. CHROMOSOME MUTATION: Change in the structure or number of whole chromosomes.
Components of virus
1. Genome: RNA or DNA = acts as genetic code 2. Capsid layer: Protein shell (capsomeres) enclosing the genome
Four stages of aerobic respiration
1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Oxidative phosphorylation
Appearance of neutrophil
1. Granulated cytoplasm 2. Lobed nucleus
Golgi apparatus
1. Group of fluid filled (cisternae) flattened sacs bound by membranes. 2. Processes and packages new lipids and proteins and transports them. 3. Makes lysosomes.
Centrioles and microtubules
1. Small hollow cylinders containing a ring of microtubules. 2. Involved with the separation of chromosomes during cell division.
Gaseous exchange in alveoli
1. HIgh O2 concentration in alveolus, low O2 concentration in capillary = concentration gradient. Oxygen diffuses out of the alveolus down a concentration gradient, across the alveolar epithelium and the capillary epithelium and into the haemoglobin in the red blood cells. 2. High CO2 concentration in capillaries, low CO2 concentration in alveoli = concentration gradient. Carbon dioxide diffuses into the alveolus from the blood down a concentration gradient, crossing the capillary and alveolar endothelium. After entering the alveolar space it is breathed out.
Effect of carbon dioxide on oxygen saturation
1. Haemoglobin gives up its oxygen more readily at higher partial pressure of carbon dioxide. 2. When cells respire they produce CO2, so raising the pCO2, so allowing more oxygen to get to cells during activity, by increasing the rate of oxygen unloading.
Combining oxygen and haemoglobin
1. Haemoglobin has a high affinity for oxygen, each molecule can carry 4 oxygen molecules. 2. In the lungs, oxygen binds to the iron in haemoglobin to form oxyhaemoglobin. 3. This is reversible, when oxygen dissociates from oxyhaemoglobin near the body cells, haemoglobin is formed again. Hb + 4O2 <-> HbO8
Haemoglobin saturation and partial pressure of oxygen
1. Haemoglobin's affinity for oxygen varies depending on the partial pressure of oxygen: -High partial pO2(lungs) = oxygen loads onto haemoglobin to form oxyhaemoglobin. -Low partial pO2(respiring tissue) = Oxygen dissociates form oxyhaemoglobin. 2. Oxygen enters blood capillaries at the alveoli in the lungs - Alveoli have a high pO2 so oxygen loads onto haemoglobin -> oxyhaemoglobin. 3. Respiring cells use up oxygen - this lowers the pO2. Red blood cells deliver the oxyhaemoglobin to respiring tissue, where it unloads its oxygen. 4. The haemoglobin then returns to the lungs to pick up more oxygen.
Function of cholestrol in plasma membrane
1. Has hydrophilic head and hydrophobic tails. 2. Helps to regulate fluidity of the membrane = not too rigid, no too fluid.
Optimum conditions for photosynthesis
1. High light intensities of a certain wavelength -light needed to provide the energy for the light-dependent reaction. -only certain wavelengths of light used in photosynthesis. 2. Temperature around 25 degrees: -so enzymes (e.g. rubisco) function at optimum temp -Stomata close if temperatures are too high to reduce water loss 3. Carbon dioxide at 0.4%
Effect of substrate concentration on enzyme activity
1. Higher substrate concentration = higher rate of reaction: More substrate molecules means collision frequency between enzymes and substrate molecules increases, so more active sites will be used up. 2. When saturation point is reached there are so many substrates that all the active sites are full, and adding more makes no difference.
How does the hormonal system send information as chemical signals?
1. Hormonal system made up of glands and hormones 2. Hormones are secreted when a gland is stimulated (by a change in concentration of a specific substance or by electrical impulses) 4. Receptors on gland detect change in concentration. 3. Gland secretes hormones which diffuses into the blood and are carried around the body via circulatory system. 4. They diffuse out of the blood all over the body but only bind to its specific complementary receptors found on TARGET CELLS. 5. Hormone triggers a response in the target cells (effectors)
Why is hormone called first messenger and signalling molecule called second messenger?
1. Hormone = first messenger - carries chemical message first part of way from gland to receptors on target cells. 2. Signalling molecule = second messenger - carries chemical message second part of way from receptor of target cell to other parts of cell
Example of first and second messenger molecule involvement in hormonal communication
1. Hormone adrenaline is a first messenger. 2. It binds to specific receptors in the cell membranes of many cells e.g. liver cells 3. When adrenaline binds it activates an enzyme in membrane called adenylate cyclase. 4. Activated adenylate cyclase catalyses production of second messenger - cyclic AMP (cAMP) 5. cAMP activates cascade, e.g. cascade of enzyme reactions make more glucose available to cell.
How have wheat crops been improved by selective breeding?
1. Humans select plants with desirable characteristics and breed them together (e.g. those with bigger grains) 2. Offspring with the desirable characteristics are bred. 3. This is continued over several generations. 4. Frequency of desirable allele increased.
Secondary response is faster
1. If the same antigen enters the body again, the immune system will produce a quicker, stronger immune response - secondary response. 2. Memory B-cells: divide into plasma cells that produce the right antibody to the antigen. Memory T-cells: divide to correct type of T-cells to kill the cell carrying the antigen. 3. The secondary response often gets rid of the pathogen before you begin to show any symptoms.
Resting muscle description
1. In resting muscle the actin-myosin binding site is blocked by tropomyosin, which is held in place by troponin. 2. So myofilaments can't slide psat each other as the myosin heads can't bind to the actin-myosin binding site on the actin filaments.
: Why doesn't vaccination cause illness even it involves injecting pathogens into the body
1. Inactivated form of pathogen used (heat treatment) which still has immune-stimulating antigens. 2. A weakened form of the pathogen (attenuated) is used which is less virulent. 3. Contain isolated antigens.
Monocytes
1. Inactive cells which circulate in the blood (developed in bone marrow, mature elsewhere) 2. Eventually leave the blood when they receive chemical signals indicating presence of bacteria or viruses. 3. As monocytes mature they develop more RER, golgi apparatus and lysosomes. 4. When they leave the blood they become macrophages.
How to increase reliability?
1. Increase sample size 2. Increase number of repeateats
Effect of enzyme concentration on enzyme activity
1. Increased enzyme concentration = increased rate of reaction (more active sites available): More enzyme molecules = more likely for substrate molecules to collide with enzyme and form enzyme-substrate complex. 2. But if substrate is limited, there comes a point when there are more than enough enzyme molecules to deal with the available substrate = any further increase in enzyme concentration has no effect on rate of reaction.
What is genetic variation caused by?
1. Independent assortment of chromosomes, and therefore alleles, during meiosis. 2. Crossing over between chromatids of homologous chromosomes during meiosis. 3. random mating between organisms within a species. 4. Random fertilization of gametes. All cause reshuffling of alleles 5. Mutation Introduces new allele
Natural selection
1. Individuals in a population show variation in characteristics. 2. Predation, disease and competition leads to struggle for survival. 3. Individuals with the better adaptation are more likely to survive, reproduce and pass on the alleles that cause the favourable adaptation to the offspring. 4. Overtime, there is an increase in the number of individuals with the favourable adaptation. 5. Over generations this leads to evolution as the favourable adaptation becomes more common in the population.
Advantages of producing human proteins by recombinant techniques
1. Insulin reliable supply available for increasing demand is not dependent on factors e.g.: meat trade acts faster than animal insulin or slower over a long period of time 2. Factor VIII - genetically modified hamster cells produce factor VIII Factor VIII is extracted and purified before being used to treat patients with haemophilia avoids the risk of infection e.g.: HIV from donated blood 3. adenosine deaminase (ADA) - used to treat SCID (severe combined immunodeficiency disease) - produced from genetically modified larvae of cabbage looper moth caterpillar - administered to patients when: waiting for gene therapy gene therapy is not possible
Smooth muscle description
1. Involuntary muscle contraction that is controlled unconsciously. 2. Called smooth muscle as it doesn't have striped appearance of skeletal muscles. 3. Found in walls of hollow internal organs e.g. blood vessels, gut -smooth muscle in gut contract to move food along (peristalsis) 4. Each muscle fibre only has one nucleus
Haemoglobin features
1. Large protein with a quaternary structure. 2. 4 polypeptide chains (2 alpha and 2 beta) 3. Each chain has a haem group, containing iron (Fe2+) making it red.
Nucleus
1. Largest organelle surrounded by nuclear envelope which contains many pores. 2. Contains chromatin and nucleolus. 3. Chromatin made of proteins and DNA which controls the cell's activities. 4. Nuclear pores allow movement of substances between nucleus and cytoplasm.
Why is anaerobic respiration less efficient than aerobic respiration? (3)
1. Less ATP produced per molecule of glucose. 2. Lactate still contains energy, only glycolysis involved. 3. Not sustainable / cannot go on indefinitely.
Two stages of photosynthesis
1. Light dependent reaction (thylakoid membranes) -Light energy absorbed by photosynthetic pigments in photosystems and converted to chemical energy. -Light energy used to add phosphate group to ADP -> ATP and to reduced NADP. -ATP transfers energy. Reduced NADP transfers hydrogen to light-independent reaction. 2. Light independent reaction (Stroma) -ATP and reduced NADP from light-dependent reaction supply energy and hydrogen to make glucose from CO2.
Non-cyclic photophosphorylation (simple)
1. Light energy excites electrons in chlorophyll 2. Photolysis of water produces protons, electrons and oxygen. 3. energy from excited electrons makes ATP... 4. ...and generates reduced NADP
Adaptations of xylem (simple)
1. Lignified cell walls 2. Vessel elements have no end walls 3. Dead cells = no contents 4. Pits in cell wall 5. Narrow lumen (adhesion)
Phloem
1. Living vascular tissue that transports substances made in the plant, e.g. sucrose and amino acid to all other parts. 2. Living vascular tissue that carries sugar and organic substances throughout a plant
Cellulose structure
1. Long, unbranched chain of beta-glucose. 2. Bonds between the sugars are straight, so cellulose chains are straight. 3. Cellulose chains are linked together by hydrogen bonds to form strong fibres called microfibrils.
Components of veins and arteries
1. Lumen (vein = wider) 2. Endothelium (artery = folded) 3. Elastic fibres (artery = more) 4. Smooth muscle (artery = more) 5. Fibrous tissue (artery and vein = same) 6. Connective tissue (vein = more)
Emphysema
1. Lung disease caused by smoking or long term exposure to air pollution where foreign particles in the smoke become trapped in the alveoli. 2. This causes inflammation, encouraging phagocytes to the area. 3. The phagocytes produce an enzyme that breaks down the elastic fibres. 4. This makes the alveoli less elastic (lungs lose elasticity). 5. Alveolar walls may be destroyed resulting in larger air spaces, and reducing the surface area of the alveoli ( SA available for gas exchange). 6. So rate of gaseous exchange decreases.
Structures found in animal cells but not plant cells
1. Lysosomes 2. Centrioles
Structure and functions of the different types of neurones
1. MOTOR NEURONES: -Many short dendrites carry nerve impulses fro CNS to cell body. (Many highly branched dendrites to give large surface area for endings of other neurones) -One long axon carries nerve impulses from cell body to effector cells over long distances -Cell body in CNS 2. SENSORY NEURONES: -One long dendrite carries nerve impulses from receptor cells to the cell body. -short axon/medium carries nerve impulses from cell body to the CNS. -Cell body in small swellings = ganglia 3. RELAY NEURONES: -Many short dendrites carry nerve impulses form sensory neurones to the cell body. -Many short axons carry nerve impulses form cell body to motor neurones.
What factors affect the speed of conduction of action potentials?
1. MYELINATION Myelinated neurones allows saltatory conduction = faster 2. AXON DIAMETER Greater diameter = quicker conduction of action potential due to less resistance to flow of ions than in cytoplasm of smaller axon. With less resistance, depolarisation reaches other parts of neurone cell membrane quicker. 3. TEMPERATURE Temperature proportional to speed of conduction as ions diffuse faster. Only increases until 40 degrees as proteins begin to denature and speed decreases.
Ribosome
1. Made of large and small subunits. 2. Smallest organelle that floats free in cytoplasm, or attached to RER. 3. Site of protein synthesis.
How does the nervous system send information as electrical impulses?
1. Made up of complex network of neurones (sensory, relay and motor neurones. 2. Stimulus is detected by receptor cells and an electrical impulse is sent along a sensory neurone. 3. When electrical impulse reaches end of a neurone, chemicals called neurotransmitters take the information across to the next neurone, which then sends an electrical impulse. 4. The CNS processes the information, decides what to do and sends impulses along motor neurones to an effector. 5. Response generated
Fibrous proteins
1. Made up of long, insoluble polypeptide chains tightly coiled round each other to form rope shape. 2. The chains are held together by lots of bonds (e.g. disulfide and hydrogen bonds) making the proteins strong.
Prevention and control of measles
1. Maintain a good diet for good health. 2. Vaccination is the best defence. People likely to suffer from disease are people who are malnourished and live in areas where no vaccination programme is available.
Consequences of refractory periods
1. Make sure there is a time delay between one action potential and the next. Makes sure that action potentials don't overlap but pass along as discrete impulses. 2. There is a minimum time between action potentials occurring at any one place on a neurone. 3. The length of the refractory period determines the maximum frequency at which impulses are transmitted along neurones.
What makes glycogen good for storage
1. Many branches, so stored glucose can be released quickly = important for energy release in animals. 2. Compact molecule, so good for storage. 3. Insoluble in water, does not affect cell's water concentration, so does not cause water to enter cell by osmosis. 4. Large molecule, so can store lots of energy.
Cohesion-adhesion force key words
1. Mass flow of water 2. Hydrogen bonds 3. Continuous column 4. Water sticking onto plant surfaces 5. Movement due to difference in hydrostatic pressure 6. Against gravity
How can you follow what happens overtime in an enzyme catalysed reaction
1. Measure rate of disappearance of substrate. 2. Measure rate of formation of product.
Cell signalling features
1. Membrane-bound proteins act as receptors for messenger molecules. 2. Receptor molecules have specific shapes, only messenger molecules with complementary shape can bind with them. 3. Different cells have different types of receptors, so they respond to different messenger molecules.
Where is circular DNA found
1. Mitochondria 2. Prokaryotes
Active transport process (carrier protein)
1. Molecule attaches to the carrier protein in the membrane. 2. The protein changes shape. 3. This moves the molecule across the membrane releasing it on the other side. Energy is used from ATP to move the solute against its concentration gradient.
Types of inheritance/genetic crosses
1. Monohybrid inheritance 2. Dihybrid inheritance 3. Test crosses 4. Codominance 5. Multiple alleles 6. Sex linkage 7. Interactions between loci 8. Autosomal linkage
Problems with control of malaria
1. Mosquitos will still breed in the tiniest bodies of water. 2. Using insecticides may harm human health and cause resistance. 3. Many areas have dense populations 4. Tropical area/climate = ideal conditions for mosquitoes
Normal blood glucose concentration
80-120 mg per 100ml
Sickle cell anaemia cause
1. Mutation causes change in the gene that codes for the B-polypeptide in haemoglobin. 2. Gene has T in place of A = difference in triplet = so different amino acid used during construction of the polypeptide chain. 3. Abnormal B-polypeptide has the amino acid valine (GTG = DNA) in place of glutamic acid (GAG). 4. The amino acids glutamic acid and valine are on the outside of the haemoglobin molecule when it takes up its tertiary and quaternary shape. 5. Glutamic acid is hydrophilic making the haemoglobin molecule soluble. 6. Valine is hydrophobic (does not interact with water) making haemoglobin less soluble.
Sliding filament theory
1. Myosin and actin filaments slide over one another to make the sarcomeres contract - the myofilaments themselves don't contract. 2. The simultaneous contraction oflots of sarcomeres means myofibrils and muscle fibres contract. 3. Sarcomeres return to their original lengths as the muscle relaxes.
Structure of myosin filaments
1. Myosin filaments have globular heads that are hinged so can move back and forth. 2. Each myosin head has a binding site for actin and binding site for ATP. 3. Actin filaments have binding sites for myosin heads = actin-myosin binding sites 4. Two other proteins, tropomyosin and troponin found between actin filaments. -These proteins are attached to each other and help myofilaments move past each other.
Tissue fluid formation process
1. Near the arterial end of a capillary, there is a relatively higher pressure inside the capillary than in fluid between cells. 2. The difference in pressure forces the plasma (water and other smaller molecules) out through the capillary wall, through the gaps between the cells in the wall. 3. This plasma fills the spaces between the body cells and is now called tissue fluid. 4. The tissue fluid bathes the body cells, substances such as oxygen, urea etc can move between the blood plasma and the body cells by diffusing through the tissue fluid. 5. The plasma proteins remaining in the blood plasma exert an osmotic effect, drawing some water back into the capillary, but not enough to counteract the net movement by difference in pressure. 6. At the venous end of the capillary there is a relatively lower pressure than in the tissue fluid (OR difference in water potential), producing a pressure gradient for the fluid to flow down. 7. So some water/fluid moves back into the capillaries.
Two types of information transfer to control body's activities
1. Nerves that transmit information in the form electrical impulses. 2. Chemical messengers called hormones that travel in the blood.
Difference between nervous and hormonal system communication
1. Nervous system is faster: -Electrical impulses are transmitted very fast so response is rapid allowing rapid reaction to stimuli. -Hormones aren't directly released onto target cells, but must travel through blood. 2. Nervous response is short lived: -Neurotransmitters are quickly removed once job is done. -Hormones aren't broken down as quickly as neurotransmitters, so effects of hormones last longer. 3. Nervous response is localized: -When electrical impulse reaches end of neurone, neurotransmitters are secreted directly onto cells (e.g. muscle cells) -Hormones are transported all over the body, so response may be widespread if target cells are widespread.
Resting potential
1. Neurone's resting state (when not bein stimulated) outside of membrane more positive compared to inside = POLARISED (more positive ions outside) 2. Difference in voltage across the membrane of neurone at rest = RESTING POTENTIAL (-70mV)
Processes by which antibodies inactivate pathogens
1. Neutralisation 2. Agglutination
Effect of nicotine on the cardivasculour system
1. Nicotine is absorbed readily by blood, and travels to the brain within few seconds. 2. This stimulates: - nervous system causing smooth muscles to contract to reduce diameter of arterioles - increases release of adrenaline from adrenal glands 3. Therefore the heart rate and blood pressure is increased. 4. There is a decrease in blood supply to the extremities of the body e.g. hands and feet, reducing their supply of O2. 5. Nicotine also increases the risk of blood clots forming.
Components of smallest bronchioles
1. No cartilage 2. No smooth muscle 3. Elastic fibres 4. No goblet cells 5. No cilia
Components of larger bronchioles (terminal bronchiole)
1. No cartilage 2. Smooth muscle 3. Elastic fibres 4. Goblet cells 5. Ciliated epithelium
Components of smaller bronchioles (respiratory bronchiole)
1. No cartilage 2. Smooth muscle 3. Elastic fibres 4. No goblet cells 5. Ciliated epithelium
Components of alveoli
1. No cartilage (has surfactant in fluid lining to prevent collapse) 2. No smooth muscle 3. Elastic fibres (around) 4. No goblet cells 5. No cilia
Appearance of lymphocyte
1. No granules in cytoplasm 2. Circular nucleus 3. Huge nucleus taking up almost entire space of cell
Appearance of monocyte
1. No granules in cytoplasm 2. Kidney (horse shoe shaped nucleus) 3. Largest white blood cell
Non-competitive inhibition
1. Non-competitive inhibitor molecules bind to the enzyme away from its active site. 2. This causes the active site to change shape so the substrate can no longer bid to it. 3. They don't compete with the substrate molecules to bind to the active site because they have a different shape.
Formation of lymph
1. Not all the tissue fluid returns to the capillaries. The remaining tissue fluid collects in lymphatic vessels. 2. It is then called lymph. 3. This eventually gets returned to the blood via the lymphatic system.
Hormones involved in the menstrual cycle
1. Oestrogen 2. Progesterone 3. FSH - follicle-stimulating hormone 4. LH - luteinising hormone
Proteins involved in facilitated diffusion (transport proteins)
Carrier proteins Channel proteins
All or nothing nature of action potentials
1. Once threshold is reached, action potential will always fire with same change in voltage, no matter how big the stimulus. 2. If threshold isn't reached, action potential won't fire. 3. Bigger stimulus won't cause bigger action potential, but will cause them to fire more frequently.
Cell signalling process
1. One cell releases a messenger molecule (e.g. hormone) 2. This molecule travels to another target cell (e.g. in the blood) 3. The messenger molecule is detected by the cell because it binds to a receptor on the target cell's cell membrane. 4. The cell then responds to the messenger molecule by a change in activity.
Treatment for cholera
1. Oral rehydration salts - controls the symptoms as it helps rehydrate, diarrhoea reduced. 2. Antibiotics
Problems with treatment of cholera
1. Oral rehydration salts only help with they symptoms 2. Antibiotic resistance 3. Too late to receive treatment
What is homeostasis used to control? (homeostatic mechanisms)
1. Osmoregulation 2. Thermoregulation 3. Blood glucose control 4. pH control 5. Water potential of blood 6. Metabolic wastes e.g. CO2 and urea
How is the diffusion gradient between the alveoli and the capillaries maintained
1. Oxygen concentration gradient: i) Ventilation - air drawn into alveoli = high O2 concentration in alveoli ii) Blood flow - oxygenated blood carried away = low O2 concentration in capillaries. 2. Carbon dioxide concentration gradient: i) Ventilation - air drawn out of alveoli = low CO2 concentration in alveoli. ii) Blood flow - deoxygenated blood brought in capillaries = high CO2 concentration in capillaries.
What is the light energy absorbed by the photosystems used for uin the light dependent reaction?
1. PHOTOPHOSPHORYLATION - making ATP from ADP + Pi 2. Making reduced NADP from NADP 3. PHOTOLYSIS - Splitting water into protons, electrons and oxygen.
Secondary response features
1. Pathogen enters for 2nd time 2. Fast and stronger 3. Cells activated = Memory cells 4. No symptoms exhibited (secondary response fast so gets rid of pathogen before symptoms shown)
Primary response features
1. Pathogen enters for first time 2. Slow 3. Cells activated = B- and T-cells 4. Symptoms exhibited
Neutrophils
1. Patrol body tissues. 2. Develop and mature in the bone marrow. 3. Leave the blood at sites of infection Engulf and digest bacteria in a similar way to macrophages. (phagocytosis) 4. Only engulf few pathogens before they die, lives only for few days. 5. dead neutrophils form pus.
Macrophages
1. Patrol tissues, but are much larger than neutrophils. 2. They have a longer lifespan than neutrophils (monocytes + macrophages = several months) 3. They are formed from the maturation of monocytes. 4. They engulf bacteria by endocytosis and digest them. (phagocytosis) 5. When they break down pathogens they can display the antigen on their surface to show the T cells.
Amongst which people is TB most common
1. People living in poor accommodation. 2. Poor immune system because of malnutrition or infection with HIV.
Components of cell surface membrane
1. Phopsholipid molecules 2. Integral proteins 3. Peripheral proteins 4. Glycoproteins (proteins with polysaccharide chain attached) 5. Glycolipids (lipids with polysaccharide chain attached) 6. Cholestrol
Components of a nucleotide
1. Phosphate group 2. Pentose sugar (deoxyribose/ribose) 3. Nitrogen containing base
Fluid mosaic structure of cell surface membranes
1. Phospholipid molecules form a continuous double layer. Fluid bilayer: Phospholipid and protein molecules move around within the layer. 2. Mosaic = composed of different parts: Plasma membrane is composed of different kinds of macromolecules/ Protein molecules are scattered through the bilayer. As the bilayer is fluid the proteins can move around within it.
What is the light energy absorbed in the light dependent reaction used for? [3]
1. Photophosphorylation: Making ATP from ADP and inorganic phosphate 2. Making reduced NADP from NADP 3. Photolysis: Splitting water into protons, electrons and oxygen
Uses of water in plants
1. Photosynthesis 2. To keep cells turgid providing mechanical support 3. Transpiration
Transmission of malaria
1. Plasmodium is transmitted in the saliva of female Anopheles mosquitoes, which injects saliva to prevent blood clotting when they feed on the blood of a person. 2. When a mosquito bites an infected person, Plasmodium is taken up into the mosquito's body and eventually reaches the salivary glands. 3. Mosquitoes are the vector for malaria.
Synaptic transmission (general process)
1. Presynaptic neurone (one before neurone) has swelling = presynaptic knob. Contains vesicles filled with chemicals called neurotransmitters. 2. when an action potetnial reaches the end of a neurone it causes the neurotransmitters to be released into the synaptic cleft. They diffuse across to the postsynaptic membrane and bind to specific receptors. 3. When neurotransmitters bind to receptors they might -trigger an action potential (in neurone) -cause muscle contraction (in muscle cell) -cause hormone secretion (gland cell) 4. Recepotrs only on postynapic membrane, making sure impulse can only travel in one direction. 5. Neurotransmitters are removed from cleft so response doesn't keep happening e.g. they're taken back into presynaptic neuron or broken down by enzymes (products taken back into presynaptic neurone)
Stages of mitosis
1. Prophase 2. Metaphase 3. Anaphase 4. Telophase (Cytokinesis)
Difference between haemoglobin and collagen
1. Protein type: C- Fibrous H- Globular 2. Shape: C- Long polypeptide chains with cross links H- Tightly folded into spherical shape 3. Solubility: C- Insoluble H- Soluble 4. Composition: C- 3 polypeptide chains coiled around each other H- 2 alpha and 2 beta polypeptide chains + inorganic prosthetic haem group 5. Amino acid constituents: C- 35% glycine H- wide range 6. Function: C- Forms supportive tissue in animals (structural protein) H- Carries oxygen around the body in the blood
The 4 kingdoms
1. Protoctista 2. Fungi 3. Plantae 4. Animalia
What is continuous variation and why does this type of variation occur in a population?
1. Range of phenotypes with normal distribution. 2. Genes and environment have an effect on the phenotypes e.g. light intensity.
What indicates rate of respiration?
1. Rate of oxygen being used up. 2. Rate of carbon dioxide produced.
Effect of temperature on enzyme activity
1. Rate of reaction increases: -More kinetic energy, so increased speed of molecules, so increased collision frequency. -Energy of collisions also increases, so each collision more likely to result in a reaction. 2. Rise in temperature = enzyme vibrates more. If temperature goes above certain level, this vibration breaks some of the bonds that hold the enzyme in shape. 3. The active site changes shape and the enzyme and substrate no longer fit together = enzyme is denatured = no longer functions.
Description of how homeostatic systems detect a change and respond by negative feedback
1. Receptors detect when parameter level too high/low (i.e. a stimuli) and information communicated to effectors via endocrine or nervous system. 2. Effectors respond to counteract change bringing level back to normal 3. This is called the NEGATIVE FEEDBACK MECHANISM -Mechanism which restores levels back to normal and maintains levels around set point 4. Negative feedback only works within certain limits -if change is too big, effectors won't be able to counteract change
Oxidative phosphorylation steps
1. Reduced NAD/FAD oxidised to NAD/FAD, releasing hydrogen atoms which splits into protons and electrons. 2. The electrons move along the ETC, losing energy as they pass each electron carrier. 3. This energy is used by the electron carriers to pump protons from the mitochondrial matrix into the intermembrane space. 4. The concentration of protons is now higher in the intermembrane space than in the mitochondrial matrix - forming a electrochemical gradient. 5. Protons move down the electrochemical gradient, back into the mitochondrial matrix, via ATP synthase. This movement (electric potential energy used) drives the synthesis of ATP from ADP and Pi. 6. At the end of the ETC, protons, electrons and oxygen combine to form water. Oxygen = final electron acceptor.
Prevention and control of malaria
1. Reducing population of mosquitoes: - removing sources of water in which they can breed e.g. water drainage - releasing large numbers of sterile males - use insecticides to kill them reduction in transmission of malaria 2. Preventing mosquitoes from biting people: - sleeping under a mosquito net - wear long sleeves, or insect repellent reduces the chances of mosquitoes picking up Plasmodium from an infected person or passing it on to an uninfected person. 3. Prophylactic drugs can be taken (prevent pathogens infecting and breeding inside a person) 4. Vaccination
Function of membranes at surface of cells
1. Regulate the movement of substances in and out of the cells. 2. Isolate the cytoplasm from the external environment. 3. Allows cell communication 4. Allows cell recognition
Cell surface membrane
1. Regulates the movement of substance into and out of the cell. 2. Has receptor molecules on it, allowing response to chemicals e.g. hormones
Things that blood transports
1. Respiratory gases 2. Products of digestion 3. Metabolic wastes 4. Hormones
Components that work together to help breathe in and out
1. Rib cage 2. Intercostal muscles 3. Diaphragm
Adaptations of rice for wet environements
1. Rice plant stems contain loosely packed cells forming tissue called AERENCHYMA. So gas can easily diffuse through even underwater. 2. Still respire anaerobically and produce ethanol. Rice plants have higher tolerance to ethanol. 3. Produce more alcohol dehydrogenase to break down ethanol.
Cell wall
1. Rigid structure surrounding plant cells. 2. Made of mainly cellulose 3. Provides mechanical support and protection. 4. Prevents osmotic bursting of cell
Function of xylem and phloem related to part of plant they are found in
1. Roots: Xylem + phloem found in centre to provide support for the root as it pushes through soil 2. Stem: Xylem + phloem found near outside to provide sort of scaffolding/mechanical support to reduce bending. 3. Leaf: Xylem + phloem form network of veins to provide support for thin leaves.
Electrochemical cell
An electrical circuit made from two metal electrodes dipped in salt solutions and connected by a wire.
Globular proteins
1. Round, compact proteins made up of multiple polypeptide chains. 2. The chains are coiled up so that: -hydrophobic parts of the chain face inwards -hydrophilic parts of the chain are on the outside of the molecule. 3. This makes the proteins soluble, so they're easily transported in fluids.
Primary defences
1. SKIN: - Has harmless bacteria which prevents colonisation of other bacteria. - Sebaceous and sweat glands secret sebum and sweat, causing the surface to have an acidic pH (3-5). This acidity prevents colonisation of other bacteria. 2. RESPIRATORY SYSTEM: - The cilia of the ciliated epithelium and goblet cells secreting mucus work together to trap and move pathogens away from the alveoli. 3. DIGESTIVE SYSTEM: - Stomach = acidic conditions kills the ingested pathogens. - Harmless bacteria in the intestines competitively exclude pathogenic bacteria.
Types of gene-gene interactions
1. SUPPLEMENTARY GENES: ->When dominant allele must be present at one gene locus for the expression of another gene. (3 phenotypes) e.g. Mice that are homozygous recessive (cc) for the colour gene cannot produce melanin. A second gene influences the colour dispersal. -B = black fur -b = brown fur i.e. one gene determines if there is colour and the other determines the type of colour 2. COMPLEMENTARY GENES: -> When the phenotype requires that there is one dominant allele at each of gene loci. (2 phenotypes) Two enzymes involved in the pigment formation. 3. DUPLICATE GENES: ->Phenotypes is expressed if either of the dominant alleles at two loci are present. Here there are two chemical pathways, either would produce the phenotype.
Large permanent vacuole
1. Sac bound by single membrane = tonoplast. 2. Contains cell sap, a concentrated solution of various substances e.g. mineral salts, sugars, enzymes etc 3. Storage of various substances, including waste. 4. Contributes to osmotic properties of cell.
Structure of muscle fibres
1. Sarcolemma: Cell surface membrane of muscle fibre 2. Sacroplasm: Cytoplasm of muscle fibre 3. T-tubules (transverse tubules): -Bits of sarcolemma fold inwards across muscle fibre and stick into sarcoplasm. -Help to spread electrical impulses throughout the sarcoplasm so they reach all parts of muscle fibre. 4. Sarcoplasmic reticulum: -Network of internal membranes that run through sarcoplasm. -Stores and release calcium ions needed for muscle contraction. 5. Multinucleated 6. Myofibrils: -Long cylindrical organelles made up of proteins (actin and myosin) - highly specialised for contraction.
Functions of the different types of neurons
1. Sensory neurones: Transmit impulses form receptors to the CNS 2. Relay neurones: Transmit impulses from sensory neurones to motor neurones (transmit action potentials through the CNS) 3. Motor neurones: Transmit impulses from CNS to effectors
Cardiac cycle
1. Sequence of contraction and relaxation of the atria and ventricles keeping blood continuously circulating around the body. 2. Volume of atria and ventricles changes as they contract and relax. 3. Pressure changes also occur, being caused by changes in the volume of the chambers.
Symptoms of lung cancer
1. Shortness of breath 2. Chronic cough which may bring up blood 3. Chest pain 4. Fatigue 5. Weight loss (tumour uses lots of nutrients and energy to grow)
Symptoms of emphysema
1. Shortness of breath (struggle to breathe deeply, especially during exercise) 2. Wheezing 3. Increased breathing rate, in order to increase amount of air containing oxygen reaching their lungs.
Dissociation curves
1. Shows how saturated the haemoglobin is with oxygen at any given partial pressure = shows how affinity for oxygen vaires 2. y-axis = % saturation of haemoglobin with oxygen x-axis = % partial pressure of O2 / kPa 3.
Adaptation of phloem tissue (explained)
1. Sieve plates - perforated end walls allowing mass flow of assimilates/phloem sap through pores. 2. No nucleus + few organelles + thin layer of cytoplasm - leaving space for movement of phloem sap. 3. Cell wall with many plasmodesmata - forming direct links between cytoplasms of sieve tube elements and companion cells. 4. Comapnion cells - containing may organelles including nucleus and mitochondria, so can carry out functions for sieve tube elements.
Function of companion cells
1. Sieve tube elements don't contain nucleus and other organelles, so they can't survive on their own. Therefore each sieve tube element is associated with a companion cell. 2. Companion cells carry out the living functions for themselves and the sieve tube elements. E.g. They provide the energy for the active transport of solutes.
Lysosome
1. Simple, round organelle surrounded by a membrane. 2. Contains digestive enzymes which digest invading cells, or break down worn out components of cell.
Types of muscle
1. Skeletal muscles 2. Smooth muscles 3. Cardiac muscle
Description of movement involving muscles, tendons, ligaments and joints
1. Skeletal muscles are attached to bones by tendons. 2. Ligaments attach bones to other bones, to hold them together. 3. Structure of joints between bones determines kind of movement possible: -Ball and socket (e.g. shoulder) = movement in all directions -Gliding joints (e.g. wrist) = allows wide range of movement as bones slide over each other -Hinge joints (e.g. elbow) = allows movement in one plane only.
Why is ATP most suitable for storing energy
1. Small and soluble - easy and fast transport to areas where energy is needed 2. Easily hydrolysed - entire molecule is very unstable 3. High energy released - high for size of molecule 4. Rapid turnover - broken fast, reformed fast 5. Used by most types of cells
Features of prokaryotes (9)
1. Smaller and simpler than eukaryotic cells (1-5 um) 2. Much less organelles than eukaryotic cells (no double-membrane bound organelles) 3. 70s ribosomes 4. Cell wall made of peptidoglycan (polysaccharide + amino acids) 5. No nucleus = DNA floats free in cytoplasm 6. Naked circular DNA (not associated with any proteins to form chromosomes) 7. Plasmids = small loops of DNA (not always present) 8. Flagellum (only some) 9. Unicellular
Components of bronchi
1. Smaller irregular cartilage pieces 2. Smooth muscle 3. Elastic fibres 4. Goblet cells 5. Ciliated epithelium
When is evolution by genetic drift greatest?
1. Smaller populations 2. Genetic bottleneck 3. Smaller number of individuals separated from rest of large population
What causes water to get from soil to air
1. Soil around the roots have a high water potential. 2. Leaves have a low water potential as transpiration occurs. 3. This creates a water potential gradient. 4. As water moves down a water potential gradient, water is kept moving in the right direction, from the roots to the leaves.
Bacterial resistance to antibiotics by natural selection
1. Some bacteria in a population have alleles that give them resistance to antibiotics. 2. The population is exposed to the antibiotic, killing the bacteria without the antibiotic resistance allele. 3. The antibiotic resistant bacteria survive and reproduce, passing on the allele that gives them antibiotic resistance to their offspring. 4. After some time, more of the bacteria in the population will possess the antibiotic resistance allele.
Why doesn't aerobic respiration release as much energy as possible?
1. Some of the reduced NAd formed during the first three stages of aerobic respiration is used in other reduction reactions in the cell instead of oxidative phosphorylation. 2. Some ATP used up by actively transporting substances into the mitochondria during respiration, e.g. pyruvate, ADP, phosphate.
What can be determined by random sampling using quadrat
1. Species frequency 2. Species density
Spermatogenesis process
1. Sperm production takes place in tubules in testes. 2. Here diploid cells divide by mitosis to produce numerous spermatogonia. 3. Spermatogonia grow to form diploid primary spermatocytes. 4. First division of meiosis takes place forming two haploid secondary spermatocytes. 5. Second division of meiosis the produces haploid spermatids. Spermatids mature into spermatozoa.
What helps limit the diffusion pathway distance of gas exchange in the alveoli
1. Squamous cells = flattened 2. Alveolar and capillary epithelium = one cell thick 3. Capillaries are very narrow so RBCs are squeezed close to the walls.
Factors affecting rate of diffusion
1. Steepness of concentration gradient 2. Thickness of gas exchange surface 3. Temperature 4. Surface area
Why does transpiration occur as a result of gas exchange
1. Stomata opens to let in carbon dioxide so that photosynthesis can occur to produce glucose. 2. But this also lets water out - there is a higher concentration of water inside the leaf than the air outside, so water moves out of the leaf down a water potential gradient when the stomata open.
Collagen
1. Strong, fibrous protein that forms supportive tissue in animals. 2. Made up of three polypeptide chains that are tightly coiled into a triple helix. 3. Hydrogen bonds are formed between the chains, giving the structure strength = needed for role as structural protein. 3. Covalent cross links (covalent bonds) formed between collagen molecules = collagen molecules arrange parallel -> collagen fibrils 4. Collagen fibrils form further bonds between each other -> collagen fibres
Induced fit model process
1. Substrate fits into active site, but active site is not initially an exact fit for substrate molecule. 2. Enzyme-substrate complex formed (as substrate binds into active site, forces between the two molecules distorts enzyme and active site so it tightly envelopes the substrate. 3. Catabolic/anabolic reaction 4. Enzyme-product is formed 5. Product leaves active site, enzyme changes back to original shape, free to take part in next reaction.
Lock and key model process
1. Substrate molecule fits exactly into the active site like a key fitting into a lock, where it is held in place by temporary bonds. 2. Enzyme-substrate complex formed (activation energy lowered) 3. Catabolic reaction (one substrate molecule splits into two or more) / anabolic reaction (two substrate molecules join) 4. Enzyme-product complex formed 5. Product(s) leaves the active site, enzyme left unchanged and free to take part in another reaction.
Function of membranes within cells
1. The membranes around different organelles isolates organelles from rest of cytoplasm, allowing cellular processes to occur separately. 2. Regulate movement of substances enter and leave the organelles (e.g. RNA) 3. Provide attachment for ribosomes (RER) 4. Site for biochemical reactions.
Active loading of sucrose process
1. Sucrose move from the mesophyll cells via the symplast/apoplast pathway. Once it gets to the companion cells it is loaded into the phloem by active transport. 2. Hydrogen ions are pumped (proton pump) out of the companion cell into the cell wall, using energy derived from ATP. 3. This creates a concentration gradient, as there is an excess of hydrogen ions in the apoplastic pathway outside the companion cell. 4. The hydrogen ions can move back into the cell down their concentration gradient, through a protein (co-transporter) which acts as a carrier for both hydrogen ions and sucrose at the same time. 5. The sucrose molecules are carried through this co-transporter molecule into the companion cell, against their concentration gradient, using the concentration gradient of the hydrogen ions. 6. The sucrose molecules then move from companion cell into sieve tube through the plasmodesmata.
Chloroplasts
1. Surrounded by double membrane. 2. Contains gel like fluid = stroma in which there are thylakoid membranes that stack up in some places to form grana (s granum). 3. Grana are linked together by lamellae (thin, flat pieces of thylakoid membranes) 4. Stroma also contains starch grains, ribosomes, circular DNA. 5. Site of photosynthesis (grana or stroma) sugars produced from CO2 and water using light energy trapped in chlorophyll.
Mitochondria
1. Surrounded by envelope. 2. Inner membrane folded to form cristae. 3. Inside = matrix, contains enzymes involved in respiration. 4. Contains ribosomes and circular DNA 5. Site of aerobic respiration. 6. Found in large numbers in cells that are very active.
Neuromuscular junctions description
1. Synapse between motor neuron and a muscle cell. 2. Neurotransmitter: Acetylcholine Receptors: Nicotinic cholinergic receptors
Smooth endoplasmic reticulum
1. Synthesises and processes lipids and steroids 2. No ribosomes attached
Factors affecting rate of transpiration
1. Temperature 2. Humidity 3. Light intensity 4. Wind
Problems with treatment of TB
1. The M. tuberculosis bacterium has evolved resistance to most antibiotics. 2. The bacteria reproduce inside body cells, so it is difficult for drugs to reach them. 3. The drugs need to be taken over a long period of time, often requiring a health worker checking that a person takes their drugs everyday.
Endocytosis
1. The cell surface membrane grows out putting out extensions around the substance to be engulfed. 2. The substance is surrounded. 3. The membrane fuses together around the substance, enclosing it and forming a vesicle. 4. The vesicle moves inwards and its contents is absorbed into the cytoplasm.
Metaphase
1. The centriole pairs are at the poles. 2. Spindles are completely formed. 3. The spindle fibres attach to the centromeres of the chromosomes. 4. The spindle fibres pull on the centromeres, arranging the chromsomes along the equator.
Cytokinesis process
1. The cytoplasm divides (cell divides into two), either by infolding of the plasma membrane in animals, or the formation of a new cell wall and plasma membrane in plants. 2. Two daughter cells are formed that are genetically identical to the original parent cell and to each other.
Adaptations of the heart
1. The left ventricle of the heart has thicker and more muscular walls than the right ventricle: left ventricle need to contract powerfully to pump blood all around body, but right ventricle only needs to get blood to lungs close by. 2. The ventricles have thicker walls than the atria: ventricles need to push blood out of heart, but atria just need to push blood a short distance into the ventricles. 3. Atrioventricular valves link the atria and ventricles, and prevent the blood flowing back into the atria during ventricular systole. 4. Semilunar valves link the ventricles to the aorta and pulmonary artery, preventing blood flowing back into the ventricles after ventricular systole. 5. The tendinous cords attach the atrioventricular valves to the ventricles, preventing them from being forced up into the atria when the ventricles contract.
Lymphatic vessels process
1. The lymphatic vessels have valves that allow fluid to flow into them and along them, but preventing it from flowing backwards. 2. They carry the lymph to the subclavian veins (near the collarbone) where it is returned to the blood.
Heart beat process
1. The sino-atrial node found in the right atrium sets the rhythm of the heartbeat by sending out regular electrical impulses to the muscle of the atrial walls. 2. This causes the right and left atria to contract at the same time = Atrial systole. 3. A band of non-conducting collagen tissue prevent the electrical impulses from being passed directly from the atria to the ventricles. 4. Instead the waves of electrical activity are transferred from the SAN to the atrio-ventricular nodes (AVN) in the septum. 5. There is a slight delay before the AVN reacts, to make sure the ventricles contract after the atria are emptied. 6. The AVN then passes the electrical impulses along the bundle of His down the septum to fine muscle fibres in the the walls of the ventricles called purkyne tissue. 7. The purkyne tissue carry the electrical impulse into the muscular walls of the right and left ventricles, causing them to contract simultaneously from the bottom up. 8. There is then a short delay before the next wave of electrical activity is generated by the SAN, during which the cardiac muscle relax = DIASTOLE
Telophase
1. The sister chromatids (now effectively chromsomes) reach opposite poles. 2. The chromosomes de-condense, uncoil = long and thin 3. Nuclear envelopes begin to form around the group of chromosomes at each pole = 2 nuclei 4. Nucleolus reappears 5. The spindles disappear
Anaphase
1. The spindles contract, pulling on the centromeres, therefore the centromeres divide, separating each pair of sister chromatids. 2. The spindles pull the chromatids opposite poles of the cell, centromere first.
Process of stem cells forming specialised cells
1. The stem cells divide by mitosis to become new cells. 2. Differentiation occurs and these new cells become specialised.
Tissue repair by stem cells
1. The stem cells divide by mitosis. 2. The stem cells differentiate and develop into the specialised cells that need to be replaced. 3. Damaged cells are replaced.
How is the structure of a chloroplast adapted for photosynthesis?
1. The thylakoids have a large surface area to allow as much light energy to be absorbed as possible. 2. Lots of ATP synthase molecules are present in the thylakoid membranes to produce ATP in the light-dependent reaction. 3. The stroma contains all the enzymes, sugars and organic acids for the light-dependent reaction to take place. 4. The chloroplast envelope keeps the reactants for photosynthesis close to their reaction sites.
Ventricles relax, atria relax (Diastole)
1. The ventricles and the atria both relax. 2. There is a higher pressure in the aorta and the pulmonary artery than in the ventricles, so the semilunar valves are closed, preventing back-flow into the ventricles. 3. Blood returns to the heart by the veins, and flows into the atria due to the higher pressure in the vena cava and pulmonary vein than in the atria. 4. As the atria fill up the pressure starts to increase. 5. As the ventricles continue to relax, the ventricular pressure falls below the atrial pressure, so the AV valves open. 6. This allows blood to flow passively (without being pushed by atrial contraction) into the ventricles from the atria. 7. The atria contracts and the cardiac cycle starts.
Explain the 'S' shape of the dissociation curve (2)
1. There is initially a shallow bit = hard for first oxygen molecule to join the Hb molecule. 2. Becomes steeper, as after the first O2 molecule joins it changes the shape in a way that makes it easier for the other molecules to join. 3. Becomes shallower again to the end, because as the the Hb molecule gets more saturated, it's harder for the O2 molecules to combine with the Hb molecule.
Describe hand withdrawal response to heat (reflex action)
1. Thermoreceptors in the skin detect heat stimulus. 2. The sensory neurone carries impulses to the relay neurone. 3. The relay neurone connects to the mother neurone. 4. The motor neurone sends impulses to the effector. 5. your muscle contracts to stop your hand being damaged.
Capillary adaptations
1. Thin walls (one cell thick) minimise diffusion distance = rapid exchange between blood and body cells. 2. Large numbers of capillaries, to increase surface area for exchange. 3. Found very near cells in exchange tissue = short diffusion pathway. 4. Very small, red blood cell barely fits, so flows through slowly = all the substances diffuse into body cells.
Bronchus
1. Trachea branches into bronchi. 2. One bronchus leads to each lung. 3. Bronchi supported by cartilage (irregular + regular shaped rings)
Problems with control of HIV
1. Tracking can be expensive and difficult 2. Long incubation period. 3. Uneducated people. 4. Reluctance in use of condoms. 5. Community practices open culture.
Prevention and control of cholera
1. Transmission most likely in crowded and impoverished areas. 3. Use clean and safe water 4. Treat sewage effectively 5. Maintain good hygiene in food preparation 6. Use vaccines
Red blood cell features
1. Transport oxygen from lungs to respiring tissue. 2. Biconcave disc shape: increases surface area to volume ratio, allowing rapid diffusion of oxygen into and out of the cell. 3. Contain haemoglobin, which binds with the oxygen to form oxyhaemoglobin in areas of high concentration (lungs), and release the oxygen in areas of low concentration (respiring tissue). 4. No nucleus or mitochondria
Horizontal gene transmission
1. Two bacteria join together in a process called conjugation and a copy of a plasmid is passed from one cell to another (transferred through a stalk called a pilus). 2. Plasmids can be passed on to a member of the same species or a totally different species. a) Bacterial cell with antibiotic resistance gene in plasmid + bacteria without plasmid join together, pilus formed. b) Bacterial conjugation occurs where a copy of the plasmid containing the antibiotic resistance gene is made and is transferred through the stalk called a pilus. c) Both bacterial cells have a copy of the plasmid containing the antibiotic resistance gene.
Transmission of cholera
1. V.cholerae can enter the body in contaminated food or water. 2. The bacteria breeds in the intestine. 3. The bacteria secretes toxins which reduces the ability of the epithelium of the intestine to absorb salts and water into the blood. 4. These are lost in the faeces, causing diarrhoea. 5. If not treated the loss of fluid can be fatal. 6. Cholera is most likely to occur in places where people use water or food that has been in contact with untreated sewage, as the bacteria are present in the faeces of an infected person.
Valves in the heart
1. Valves only open one way - whether they are closed or open depends on the relative pressures of the champers. 2. Higher pressure behind a valve = forced open. 3. Higher pressure in front of valve = forced shut.
Features of veins
1. Veins carry blood back to the heart. 2. Blood is carried under low pressure. 2. Walls have little elastic or muscle tissue. 3. Wider lumen = reduced friction which would otherwise slow down blood flow. 4. Have valves to stop back flow of blood. 5. Blood flow through the veins is helped by contraction of the body muscles surrounding them. 6. All veins carry deoxygenated (oxygen used up by cells), except the pulmonary veins, which carry oxygenated blood to the heart form the lungs.
Ventricles relax, atria contract (Atrial systole)
1. Ventricles are relaxed. 2. Muscles in walls of atria contract, decreasing the volume of the chamber and increasing the pressure inside the chamber. 3. Pressure in the atria become higher than in the ventricles so the atrioventricular valves are forced open. 4. The blood is forced into the ventricles through the open atrioventricular valves. 5. There is a slight increase in the ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria.
Adaptations of xylem vessels (explained)
1. Vessel elements have no end walls = uninterrupted tube = easy, continuous movement of column of water by mass flow. 2. Dead cells = no contents (cytoplasm) = continuous movement of column of water by mass flow. 3. Lignified cell walls (also cellulose) provide strength, preventing the xylem vessels collapsing inwards when there is negative pressure inside it. 4. Pits in cell wall allows movement of water and ions out of vessel elements to other vessel elements, or surrounding tissue. 5. Narrow lumen = increased area of water in contact with wall = water molecules adhere to walls helping to prevent breakage of the column of water
Skeletal muscle description
1. Voluntary muscle contraction that is controlled consciously. 2. Made up of many long muscle fibres (multi nucleated)
How water moves from soil to xylem (1)
1. Water from the soil enters the root hair cells by osmosis. 2. Water then (travels through the roots via the root cortex into the xylem) moves to neighbouring cells by osmosis down a water potential gradient, the symplast pathway and the apoplast pathway. 3. Nearing the centre, when water in the apoplast pathway reaches the endodermis cells in the roots, its path is blocked by a waxy strip in the cell walls = CASPARIAN STRIP. 4. The water then moves into the cytoplasm by osmosis, and continues in the symplast pathway. 5. The water then moves into the xylem vessels form the endodermis.
How does water move from the soil to the air (water potential gradient)
1. Water moves from the soil to the air through a plant down a water potential gradient. 2. Water potential in soil is higher than in air. 3. Water potential in leaves is lower than in soil due to loss of water vapour by transpiration.
How water moves from xylem to air (2)
1. Water moves up the xylem vessels by mass flow: i) Hydrogen bonds = cohesion of water molecules = water column unbroken ii) Movement of water caused by pressure gradient formed from base to top of xylem vessel due to transpiration (low hydrostatic pressure at top of xylem) 2. At the leaves water leaves the xylem vessels through the pits and into the cells (across the leaf) by apoplast and symplast pathways (mainly apoplast) 3. Water evaporates from the cell walls into the air spaces. 4. When stomata opens, water diffuses out of leaf down a water potential gradient through the stomata into the surrounding air.
Haemoglobin
1. Water-soluble globular protein. 2. Composed of: -two alpha and two beta polypeptide chains -inorganic prosthetic haem group 3. Function is to carry oxygen around in the blood, and is facilitated in doing so by the presence of the haem group which contains Fe2+ ion, onto which the oxygen molecules can bind.
The primary response is slow
1. When an antigen enters the body for the first time it activates the immune system. 2. The primary response is SLOW as there aren't many B cells to make the antibodies that bind to it. 3. Eventually the body will produce enough of the right antibody to overcome the infection. Infected person shows symptoms of the disease. 4. After being exposed to the antigen, both T and B cells produce memory cells, which remain in the body for a long time. 5. Memory T-cells: -Remember the specific antigen and will recognise it a second time round. Memory B-cells: - Record the specific antibodies needed to bind to the antigen. 6. The person is now immune - their immune system has the ability to respond quickly to a second infection.
How do hormones bind to receptors and cause a response via second messengers?
1. When endocrine gland is stimulated it secretes hormones = start of hormonal communication. 2. Hormone = first messenger - as it carries the chemical message the first part of the way, from endocrine gland to receptor on target cells. 3. When hormone binds to receptor, it activates enzyme in cell membrane. 4. Enzyme catalyses production of a molecule inside cell called signalling molecule - this molecule signals to other parts of the cell to change how the cell works. 5. The signalling molecule is called a second messenger as it carries the chemical message the second part of the way, from receptor to other parts of the cell. 6. Second messenger activate a cascade (chain of reactions) inside the cell.
Translation process
1. mRNA attaches to ribosome. Two codons fit into a groove in the ribosome. 2. tRNA molecules carry amino acids to ribosome (each amino acid specific to one tRNA) 3. Using specific base pairing, tRNA molecule with the complementary anticodon to the first codon on the mRNA attaches itself to the mRNA by formation of hydrogen bonds between the complementary bases. 4. A second tRNA molecule attaches itself to the next codon on the mRNA in the same way. 5. Amino acids carried by the two adjacent tRNA molecules are linked by a peptide bond. 6. The mRNA is the moved along one place in the ribosome and the first tRNA molecule moves away, leaving its amino acid behind. 7. A third tRNA molecule binds to the next codon on the mRNA and a third amino acid is added to the chain. 8. This process continues, producing a polypeptide chain, until a stop codon is reached on the mRNA. 9. The polypeptide chain then breaks away.
ATP produced form reduced FAD
1.5
What features allows arteries to withstand the high pressure produced by the heartbeat
1.Arteries have thick, muscular walls with elastic tissue = expansion + recoil 2. Folded endothelium allows expansion
Xerophyte adaptations (7)
1.Stomata sunken in pits - sheltered from wind, slows down transpiration rate. 2.Spines instead of leaves (small leaf surface area) - reduces surface area for transpiration. 3.Fewer stomata - Less openings through which water can be lost through transpiration. 4.Thick, waxy cuticle - reduces water loss by evaporation (waxy layer is water proof) 5.Layer of hairs on the epidermis - Traps moist air around the stomata, which reduces the water potential gradient between the leaf and the air, slowing down transpiration rate. 6.Curled leaves - Traps moist air, slowing down transpiration. Lowers exposed surface area for losing water. Protects the stomata from wind. 7. Stomata on lower surface of leaf only - more humid air on lower surface.
How much is 1 Atmosphere:
100kPa
How much ATP and reduced NADP molecules are needed for six turns of the calvin cycle?
18 ATP 12 reduced NADP
What are four rules for electronic arrangement notation?
1: Each principle and subsidiary level fills up before the next one 2: When the 3p energy level is full, the 4s level fills before the 3d 3: When an atom or ion has 3d electrons, the 4s is written after the 3d 4: Atoms that have 3d electrons always lose the 4s electrons first while forming ions
How are electron subshells occupied?
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p
How many triose phosphate molecules are made for each CO2 molecule?
2
Number of hydrogen bonds formed between adenine and thymine/uracil
2
How much ATP is produced per molecule of glucose in anaerobic respiration
2 (net gain)
Standard conditions
298K 100kPa All ion solutions at concentration 1 moldm
Products when [Cr(OH)6]3- reacts with hydrogen peroxide.
2CrO4^2- +2OH- + 8H2O
Number of hydrogen bonds formed between cytosine and guanine
3
What is the lac operon made up of
3 structural genes: -Lac Z = codes forB-galactidose -Lac Y = codes for Permease (allows for passsage of lactose into cell) -Lac A = codes for transacetylase
Advantages of using Carbon for extraction
Cheap and effective, Readily available
pH of Cr3+ metal aqua ion soln
3/4
pH of Fe3+ metal aqua ion in soln
3/4
How many ATP molecules can be made from one glucose molecule
32
How long is the action potential?
3ms Depolarisation + repolarisation + hyperpolarisation -> resting potential
How many times does the calvin cycle need to turn to make one hexose sugar?
6
Diameter of cell surface membrane
7 nm
Species
A group of organisms with similar morphology and physiology (appear similar to each other) and can breed together to produce fertile offspring and are reproductively isolated from other species.
Xylem tissue composition
Contains dead, empty cells, with no end walls called vessel elements.
Species definition
A group of organisms with similar morphology and physiology that can breed together to produce fertile offspring and are reproductively isolated from other species.
What is Cracking?
A process whereby larger hydrocarbons, which have a supply exceeding the demand, can be broken into smaller fractions (which have a demand exceeding supply).
Non-self
A substance or cell that is recognised as foreign and will stimulate an immune response.
Standard hydrogen electrode
An electrode where hydrogen gas is bubbled through a solution of aqueous H ions under standard conditions
Stop codon
A codon that does not code for an amino acid e.g. UGA
pKa
= -log Ka
Equilibrium constant (Kc)
= [C]^c [D]^d / [A]^a [B]^b (where A and B are reactants and C and D are products)
Ionic product of water (Kw)
= [H^+] [OH^-]
Rate equation
= k [A]^m [B]^n
Glucose RQ (anaerobic respiration)
>1
What does the homeostatic system involve?
>Receptors (detect changes in levels) >Coordination system: -endocrine system -nervous system >Effectors (respond to counteract change)
What is a successful collision?
A collision that has the minimum amount of energy for the reacting particles to react.
What is each triplet on the DNA represented by on the mRNA
A complementary group of three bases on the mRNA called a codon.
What is volatility?
A substance's tendency to turn into a Gas. The smallest molecules are the most volatile, e.g. Fluorine (meaning it can be easily evaporated).
Why is energy form glucose used to make ATP?
A Cell can't get its energy directly from glucose
What is a Covalent Bond?
A Shared pair of electrons.
What prevents the electrical impulses from passing directly from the atria to the ventricles
A band of non-conduction collagen tissue
Ecosystem definition
A biological community of interacting organisms and the physical environment in which they live and interact with.
What are the conditions for Catalytic cracking?
A catalyst of Aluminium Oxide (Porous pot/Porcelain) or a Zeolite crystal. A slight pressure - 1 atmosphere. A temperature of 700k (relatively low).
Heterogeneous catalyst
A catalyst which is in a different physical state to the reactants.
Homogeneos catalyst
A catalyst which is in the same physical state as the reactants.
Haploid cells
A cell containing only one set of chromosomes (n).
Diploid cells
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
Target cell
A cell that responds to a particular messenger molecule
Haploid
A cell which only possesses one complete set of chromosomes (n) i.e. one of each chromosome Gametes
Diploid
A cell which possesses two complete sets of chromosomes (2n) i.e. two of each chromosome; one paternal and one maternal Normal body cells
What is Termination one of Methane?
A chlorine and methyl radical can react to form Chloromethane.
What is a Primary, Secondary and Tertiary Halogenoalkane?
A classification identifying the number of carbon atoms the carbon, to which the halogen belongs, is attached. For example, a Tertiary can contain a Methyl group from a central carbon.
Disease
A condition in which the body does not function properly, and which produces unpleasant symptoms such as pain, distress or feeling weak. (Condition lasts for several days) 1. Weakness 2. Unpleasant symptoms 3. Loss of function
Salt bridge
A connection between two half cells that ions can flow through , used to complete the circuit.
Coordinate bond(Dative covalent bond)
A covalent bond in which both electrons in the shared pair come from the same atom.
What are Catalytic converters?
A device fitted in the exhausts of modern cars, designed to convert some of the more harmful gas, such as Sulphur dioxide, unburned hydrocarbons and Nitrogen oxides, into less harmful gases.
Fuel cell
A device that converts the energy of a fuel into electricity through oxidation reaction.
What is the displayed formula?
A displayed formula shows how all the atoms are arranged and all the bonds between them
Why can't Hydrochloric acid be used instead of Nitric acid?
A false positive result would be obtained, due to the Chlorine.
Test cross
A genetic cross in which an organism with unknown genotype showing a characteristic caused by a dominant allele is crossed with an organism that is homozygous recessive to determine the unknown genotype.
Antibody
A glycoprotein made by plasma cells derived from B-lymphocytes. They are secreted in response to a particular antigen. (antigen specific)
What is a Functional Group?
A group of atoms which confer specific physical and chemical characteristic properties to a compound.
Bundle of His
A group of muscle fibres responsible for conduction the waves of electrical activity to the finer muscle fibres in the ventricle walls called the purkyne tissue.
Population
A group of organisms of the same species living in a particular area
Population
A group of organisms of the same species living in a particular area.
What are the Advantages of Catalytic cracking?
A higher proportion of branched alkanes are produced, which burn more easily than straight chains. A lower pressure and temperature. A Higher proportion of Arenes, which are valuable feedstock chemicals.
What is a homologous series?
A homologous series is a bunch of organic compounds that have the same general formula and similar chemical properties.
What are hydrogen bonds?
A hydrogen bond is a strong intermolecular force that forms between a d-positive Hydrogen atom (covalently bonded to an O, N or F) in one molecule and the O, N or F in another molecule. It is formed because of the attraction between a lone pair of electrons on the d-positive hydrogen and the d-negative atom.
How are glycosidic bonds formed
A hydrogen on one monosaccharide bonds to a hydroxyl group on the other, releasing a molecule of water, leaving behind a glycosidic bond
Polysaccharide
A large molecule consisting of many monosaccharides joined together by gylcosidic bond./A polymer with the subunit of a monosaccharide.
What are giant ionic lattices?
A lattice is just a regular structure. Ionic crystals are giant lattices of ions. Different ionic compounds have different shaped structures but they're all still giant lattices.
Amylopectin
A long, branched chain of alpha-glucose molecules. Gylocosidic bonds can be hydrolysed by carbohydrase enzymes to form monosaccharides to be used in respiration. The side branches allow the carbohydrase to get at the gylocisidc bonds easily = increased rate at which carbohydrases can hydrolyse the carboyhydrate = glucose released more quickly.
Amylopectin (simple)
A long, branched chain of alpha-glucose. the side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily = glucose can be released more quickly.
Amylose
A long, unbranched chain of alpha-glucose molecules linked by 1-4 glycosidic bonds. The angles of the glycosidic bonds give it a coiled structure, making it compact.
Magnification
A measure of how much times bigger the image size is compared to the actual size of a specimen.
Partial pressure of oxgyen
A measure of oxygen concentration -The greater the concentration of dissolved oxygen in cells, the higher the partial pressure.
Entropy
A measure of the amount of disorder in a system (e.g. the number of ways that particles can be arranged and the number of of ways that the energy can be shared out between particles).
Free energy change ΔG
A measure which links enthalpy and entropy change to predict whether a reaction is feasible. ΔG = ΔH-TΔSsystem
Complex ion
A metal ion surrounded by coordinately bonded ligands.
Purely ionic model of a lattice
A model which assumes that all ions in a lattice are spherical and have their charges evenly distributed around them.
What is a molecular formula?
A molecular formula is the actual number of atoms of each element in a molecule,
Homologous chromosomes
A pair of chromosomes in a diploid cell with the same structure, same genes (not necessarily the same alleles) at the same loci, and that pair together to form a bivalent during the first division of meiosis.
Antigen
A protein that, when introduced in the blood, triggers the production of an antibody
Equilibrium constant
A ratio worked out from the concentration of the products and reactants once a reversible reaction has reached equilibrium.
What is a substitution reaction?
A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.
Endothermic reaction
A reaction that absorbs energy. ΔH is positive.
Ligand substitution reaction
A reaction where one or more ligands are changed for one or more other ligands in a metal complex ion.
Feasible reaction
A reaction which has a a free energy change that is less than or equal to zero and will happen spontaneously.
Spontaneous reaction
A reaction which occurs by itself.
Monomer
A relatively simple molecule that is used as the sub unit in the synthesis of a polymer.
What is an Homologous Series?
A series of organic compounds where they have the same functional group and each successive member differs from the previous by CH2.
Base triplet
A series of three bases in a DNA molecule, that codes for a particular amino acid.
Monosaccharide
A simple sugar molecule that is the basic sub unit of a carbohydrate.
Isotonic solution
A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution
Hypertonic solution
A solution in which the concentration of solutes is greater than that of the cell that resides in the solution
Hypotonic solution
A solution in which the concentration of solutes is less than that of the cell that resides in the solution
Buffer
A solution which maintains pH despite the addition of acid or base
Metal-aqua complex ion
A species formed when transition metal ions dissolve in water.The water molecules form coordinate bonds with the metal ions.
What is a (free) radical?
A species with a single unpaired electron.
Allosteric site
A specific receptor site on some part of an enzyme molecule remote from the active site.
What is the structural formula?
A structural formula shows the atoms carbon by carbon, with the attached hydrogens and functional groups.
What is Sublimation?
A substance converts between solid and gaseous states without being a liquid. E.g. Iodine or Carbon dioxide.
What was Rutherford's new nuclear model for the atom?
A tiny positively charged nucleus at the centre, surrounded by a cloud of negative electrons. Most of the atom is empty space.
How do we carry out a titration?
A titration is carried out using a pipette and a burette and two solutions are mixed to determine the exact volume of one required to react with an exact volume of the other. Acid-base titrations are common, where one solution is a base (alkali) and the other is an acid.
Mitosis
A type of cell division in which a parent cell divides to produce two genetically identical daughter cells (They contain an exact copy of the DNA of the parent cell).
Macromolecule
A very large organic molecule composed of many smaller molecules. eg. proteins, nucleic acids, polysaccharides
Casparian strip
A waxy strip in the cell walls of the endodermis of the roots
Cause of HIV/AIDS
AIDS is caused by HIV (Human immunodeficiency virus) 1. This is a retrovirus, which contains RNA. 2. The virus enters T-lymphocytes, where its RNA is used to make viral DNA, which is incorporated in the T-lymphocytes' chromosomes. (HIV can only reproduce inside the cells of the organism it has infected as it doesn't have the equipment to replicate on its own) 3. Nothing happens for several years, but eventually multiple copies of the virus are made inside the T-lymphocyte, which are destroyed as the virus breaks out and infects more cells. 4. Eventually there are so few functioning T-lymphocytes that the person is no longer able to resist infection by other pathogens and develop other diseases e.g. TB. The illness alters the immune system, making people much more vulnerable to infections and diseases.
Major products of Krebs cycle
ATP CO2 Reduced NAD/FAD
How is ATP used up?
ATP diffuses to part of the cell which needs energy. Here it's broken down into ADP + Pi. Chemical energy is released from the phosphate bond and used by the cell.
How is energy released from ATP
ATP molecule is broken down to ADP by hydrolysis reaction (Covalent bond between 2nd and 3rd phosphate group is broken)
Alternative source of ATP in muscles
ATP produced from creatine phosphate (stores of this in sarcoplasm) Acts as immediate source of energy once ATP in sarcoplasm is used up. Phosphate group easily removed from each creatine phosphate molecule and combined with ADP to form ATP. [creatine phosphate + ADP -> Creatine + ATP] Later when demand for energy slowed down, ATP molecules produced by respiration used to recharge creatine [creatine + ATP -> creatine phosphate + ADP]
Enzyme catalysing ATP synthesis
ATP synthase
Enzyme catalysing breakdown of ATP
ATPase
What can be determined from the investigation of a population
Abundance and distribution Results used to calculate species frequency and density
Why is Titanium a useful metal?
Abundant, low density, corrosion resistant, strong, light alloys
What is the chemical signal that causes muscular contractions
Acetylcholine
AIDS
Acquired Immunodeficiency Syndrome
What happens to the First Ionisation Energy across a period?
Across a period, the first ionisation energy increases because there is an increase in nuclear charge, but shielding is similar as the electron is being removed from the same shell. As a result, there is a smaller atomic radius, as the outermost electron is held closer to the nucleus by the greater nuclear charge.
Amphoteric
Act as acids and bases
Cholinergic synapse process
Action potential arrives at the synaptic know of the presynaptic neurone. The action potential stimulates voltage-gated calcium ion channels in the presynaptic neurone to open. Calcium ions diffuse into the synaptic knob down a concentration gradient. Influx of calcium ions into synaptic knob causes synaptic vesicles to fuse with presynaptic membrane. Vesicles release the neurotransmitter acetylcholine (ACh) into the synaptic cleft via exocytosis. ACh diffuses across the synaptic cleft and bind to specific cholinergic receptors on the postsynaptic membrane. This causes sodium ion channels in the postsynaptic membrane causes an action potential on the postsynaptic membrane (if the threshold is reached). ACh is removed from the synaptic cleft so response doesn't keep happening. It's broken down by an enzyme called acetylcholinesterase (AChE) and the products are re-absorbed by the presynaptic neurone and used to make more ACh.
Why does active immunity last longer than passive immunity
Active immunity involves production of memory cells which last for a long time. But passive immunity only involves antibodies, which don't last very long.
What is the test for Alcohols?
Add ethanoic acid to the sample, followed by Sulphuric acid and heat. If the mixture starts to smell sweet, an alcohol was present. [Alcohols react with carboxylic acids in the presence of sulphuric acid to make esters].
How do we distinguish between Primary, Secondary and Tertiary alcohols?
Add potassium dichromate and dilute sulphuric acid and warm gently. If the mixture goes green, a primary or secondary alcohol is present. Add Fehling's solution to the green and heat. If a brick-red precipitate is formed, then a primary alcohol is present. If not, a secondary alcohol is present. If it does not go green, a Tertiary alcohol is present.
What is the test for Carboxylic acids?
Add sodium carbonate solution. If effervescence is seen and the gas produced will turn limewater milky, a Carboxylic acid was present. [Carboxylic acids can liberate carbon dioxide from carbonates].
How many molecules of ATP are produced during aerobic and anaerobic respiration?
Aerobic - 32 Anaerobic - 2
Identification of halide ions
AgNO3 and HNO3 - HNO3 removes any CO3 2- impurities which would precipitate and mask results - observe colour of ppt - dissolve in dil/conc. NH3
Coenzyme function
Aids the function of an enzyme.
Enzyme involved in the conversion of alcohol to ehtanal and back
Alcohol dehydrogenase
Alcohol + dehydrating agent
Alkenes are produced, conc. H2SO4/ H3PO4 is used, warm under reflux, acid catalysed elimination
What are the Advantages of Thermal cracking?
Alkenes are very reactive. Alkenes are a chemical feedstock for plastics.
Community
All of the organisms, of all species living in a particular ecosystem at a particular time
What are the properties of an Homologous Series?
All share the same general formula. Formulae differ from their neighbours by CH2. Contain the same functional groups. Have similar chemical properties (such as reactivity). Show a gradual change in physical properties as molar mass increases (such as boiling point). Can usually be prepared by similar methods.
Species diversity
All the species in an ecosystem. Takes species richness into account but also includes a measure of the evenness of the abundance of the different species. Greater species diversity = greater number of species + the more evenly the number of organisms is distributed amongst the different species.
Dominant
Allele that has the same effect on the phenotype of a heterozygote and homozygote
Change in temperature
Alters value of Kc
Adaptations of alveoli
Alveoli have features that speed up the rate of diffusion allowing faster rates of gaseous exchange: 1. Thin exchange surface - short diffusion pathway: i) Alveolar epithelium is only one cell thick (flattened cell) ii) Alveolar epithelial cells are squamous cells = flattened 2. Large surface area: The large number of alveoli = large surface area for gas exchange. 3. Concentration gradients of O2 and CO2 are maintained by ventilation and blood transport. 4. Capillaries very narrow so RBCs are squeezed close to the walls: -short diffusion pathway -slower flow = more time for full diffusion 5. Surfactant = speeds up transport of CO2 and O2 between the air and liquid lining the alveolus. + helps to kill any bacteria reaching the alveoli. 6. Contains elastic fibres which stretch when inhaling, and recoil to help push air out when exhaling.
What happens to excess amino acids?
Amino acids contain nitrogen in their amino groups. Body can't store nitrogenous substances, so excess amino acids are damaging. So excess amino acids must be: -used by body (e.g. protein synthesis) OR -broken down and excreted
Starch is a mixture of which two polysaccharides of alpha-glucose
Amylose Amylopectin
Transition Metal
An Element that has an incomplete d sub-shell in either its atoms or one or more of its ions
What is Carbon Neutrality?
An activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere.
Bacterial populations evolve antibiotic resistance by natural selection
An adaptation such as antibiotic resistance can become more common in a population due to natural selection.
Recessive
An allele that is only expressed when no dominant allele is present (present in homozygous)
Inert atmosphere
An atmosphere made out of a non-reactive gas like nitrogen or helium.
What happens during the ionisation stage of mass spectrometry?
An electron gun fires a beam of high energy electrons which bombards the gaseous particles, knocking off electrons leaving a positive ion
Lewis acid
An electron pair acceptor.
What is a Nucleophile?
An electron pair donor, which is negatively charged. They are attracted to an electron deficient area of another molecule (slightly positive). A curly arrow will usually come from a nucleophile.
What is an Electrophile?
An electron seeker , which is positively charged. They are attracted to an area of negativity. A curly arrow moves to an electrophile (representing the electron pair moving).
What is a P-Block element?
An element with P-electrons in its outer shell.
What is a D-Block element?
An element with S and D-electrons but no P-electrons in its outer shell.
What is an S-Block element?
An element with S-Electrons only in its outer shell.
What is the empirical formula?
An empirical formula is the simplest ratio of whole number atoms of each element in a compound.
Born-Haber cycle
An enthalpy cycle that allows you to calculate the lattice enthalpy change of formation for system.
Homozygote
An organism that carries two copies of the same allele
Heterozygote
An organism that carries two different alleles
What is mutation?
An unpredictable change in the structure of DNA, or structure and number of chromosomes of an organism.
What is a lone pair?
An unshared electron pair in a covalent bond.
Difference between plantae and animalia?
Animalia: -Motile male gametes -Heterotrophic vs autotrophic -Locomotive -Don't have cell walls
Why does glycogen have more branches than amylopectin
Animals have greater metabolic requirements. More branches = greater rate of energy release
Type of mosquito involved in transmission of Plasmodium
Anopheles mosquitoes (female) Transmitted in the saliva
Capillaries
Arterioles branch into capillaries, which are the smallest blood vessels. (Just enough space for red blood cells) Substances are exchanged between the body cells and the capillaries, so they are adapted for efficient diffusion. -Capillaries have tiny gaps between cells in their walls. Capillaries deliver nutrients, hormones and other requirements to the body cells, and take away their waste products.
Which bonds in a protein does the change in pH affect
Ionic bonds Hydrogen bonds
What is Scope?
As organic chemistry is a vast subject, it is split into small sections for study, done by studying compounds which behave in similarly because they have a particular atom, or functional group (group of atoms) in their structure.
c) explain how selection, the founder effect and genetic drift may affect allele frequencies in populations
Check ONE NOTE
Gametogenesis in flowering plants (Male gametes)
Anthers 1. Diploid pollen mother cells divide by meiosis to form four haploid cells. 2. The nuclei of each of these haploid cells then divide by mitosis, but cell itself doesn't divide (cytokinesis does not take place). 3. Results in cells that each contain two haploid nuclei. 4. These cells mature into pollen grains, each surrounded by a protective wall made up of a otugh exine and thinner intine. 5. One of the haploid nuclei is called the tube nucelus 6. Other is called generative nucleus These are the male gametes
The strands in DNA run in opposite directions, so they are....
Anti-parallel
Monoclonal antibodies
Antibodies derived from a single B-cell clone.
Passive immunity
Antibodies from elsewhere are introduced into the body
Which pathway in plants carries more water
Apoplast pathway
How can aqueous Calcium Hydroxide test for Carbon dioxide?
Aqueous Calcium Hydroxide (Limewater) turns cloudy as white Calcium Carbonate is produced.
What conditions are needed for (water solvent) nucleophilic substitution by OH?
Aqueous NaOH. The OH behaves as a nucleophile, producing an Alcohol.
How do you calculate Relative atomic mass?
Ar = Sum of(Mass of Isotopes x Relative abundance) / Sum of( Relative abundance)
Explain the Melting and Boiling point of Ar (Noble Gases):
Ar is monoatomic so has weak van der Waals forces between the atoms.
Facts about Maxwell-Boltzmann Distribution
Area = total no. of particles Y axis = no. of molecuels X axis = Kinetic energy starts at (0,0) as no molecules have no energy mean isn't at the peak of the curve Emp is at the peak (most probable energy) Energy distribution never reaches the x axis and there is no maximum energy for molecules some particles slow down after collision others speed up, allowing the reaction to reach completion
Pseudopods
Arm like structures formed by the cell surface membrane during endocytosis (phagocytosis)
How does shielding affect ionisation energy?
As the number of electrons between the outer electrons and the nucleus increases, the outer electrons feel less attraction towards the nuclear charge. This lessening pull of the nucleus by inner shells of electrons is called shielding.
How does metallic bonding explain metals ability to be shaped?
As there are no bonds holding specific ions together, the metal ions can slide over one another when the structure is pulled, so metals are malleable and ductile (can be pulled into a wire)
Action potential generation
As well as the channels that are open all the time, there are also voltage gated channels which allow the passage of Na+ and K+. P.d. across membrane determines whether they're open or closed. Membrane at resting potential = channels closed 1. STIMULUS This stimulates axon, causing voltage gated sodium ion channels in membrane to open and sodium ions diffuse into neurone down sodium ion electrochemical gradient. -This makes inside of neurone less negative (depolarisation) 2. DEPOLARISATION At first only few channels open. But with this depolarisation more channels triggered to open so more sodium ions enter (much more depolarisation) If potential difference reaches threshold (-55mV) many more sodium ion channels open and an action potential is generated with inside reaching +30mV compared with outside. 3. REPOLARISATION After about 1ms (p.d. at +30mV) sodium ion voltage gated channels close and potassium ion voltage gated channels open. Potassium ions diffuse out of the neurone down the potassium ion concentration gradient. Movement of K+ ions out removes postivie charge from inside to outside of axon, returning the p.d. to resting potentia (+70mV). 4. HYPERPOLARISATION Potassium ion channels are slow to close, so slight overshoot where too many potassium ions diffuse out of neurone. Potential difference becomes more negative than resting potential. 5. RESTING POTENTIAL The ion channels are reset. The sodium-potassium pump returns the membrane to its resting potential (pumps K+ and Na+ to maintain distribution) and maintains it until the membrane's excited by another stimulus.
What is the trend in ionisation energy across periods?
As you move across a period the general trend is for the ionisation energy to increase, it gets harder to remove an electron. This is because the number of protons is increasing which means a stronger nuclear attraction. There are small drops between groups 2 and 3 due to sub-shell structure, the electron is in a new sub-shell so further away from nucleus, more electron shielding There is a drop between groups 5 and 6 due to electron repulsion. the repulsion between two electrons in an orbital means that the electrons are easier to remove from shared orbitals.
Why is there the need for a reduction division (meiosis) prior to fertilisation in sexual reproduction?
At fertilisation, a haploid sperm fuses with a haploid egg, making a cell with the normal diploid number of chromosomes (2n). If there wasn't a reduction division, and the gametes were diploid cells, the diploid gametes would fuse and the number of chromosomes would double each generation.
What is the Effect of Increasing Concentration/Pressure?
At higher concentrations/pressures there are more particles per unit volume and so the particles collide with a greater frequency and there will be a higher frequency of effective collisions.
What is Atom economy?
Atom economy is a measure of the proportion of reactant atoms that become part of the desired product (rather than by-products) in the balanced chemical equation.
Ligand
Atom/Ion with a lone pair that forms co-ordinate bonds to metal.
What is the trend in atomic radius across a period?
Atomic radius decreases across a period. As the number of protons increases , the positive charge of the nucleus increases. This means electrons are pulled closer to the nucleus, making the atomic radius smaller. The extra electrons are added to the outer energy level so don't really provide any extra shielding.
What are Isotopes?
Atoms with the same number of protons but different numbers of Neutrons.
How does distance from the nucleus affect ionisation energy?
Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away.
Enzyme that breaks down galactose
B-galactosidase
White blood cell count
Bacterial and viral infections cause an increase in the white blood cells. -Bacterial infections = increase in neutrophils -Viral infections + TB = increase in lymphocytes -HIV = decrease in T cells (HIV invades T cells and causes their destruction) The specific white blood cell numbers provide useful information on progress of disease and success of treatment.
How do you test for the presence of Sulphate ions?
Barium Chloride solution acidified with Hydrochloric acid is used as a reagent to test for sulphate ions, where a white precipitate is formed. Other anions should give a negative result, where no precipitate is formed.
Which ones contain proteins(blood, tissue fluid, lymph)
Blood Very few in tissue fluid Only antibodies in lymph
Which ones contain white blood cells (blood, tissue fluid, lymph)
Blood Very few in tissue fluid (only enter during infection) Lots in lymph
Disulfide bonds
Bond formed between cysteine amino acid molecules. (Sulfur atom on one cysteine molecule bonds to sulfur atom on another cysteine molecule when it gets close)
What is a charge cloud?
Bonding pairs and lone pairs of electrons exist as charge clouds. A charge cloud is an area where you have a really big chance of finding an electron pair.
What is a Dynamic Equilibrium?
Both the forward and backward reactions are occuring at equal rates. The concentrations of reactants and products stays constant.
What does Dynamic mean?
Both the forward and backward reactions are occurring simultaneously.
Colour of Bromine and Bromide
Br2 → Red liquid, brown dense poisonous fumes Br- → ions Yellow solution
Digestive enzyme function
Break down large food molecules into smaller ones e.g. starch -> maltose (Other enzymes help to synthesise large molecules)
Control of gene expression in prokaryotes
Breakdown of glucose to galactose in E.coli is the most common example.
What is the chemical test for an Alkene?
Bromine (or Iodine) water will decolourise, as Bromine is an electrophile that adds onto the double bond.
How can genetic diversity be assessed?
By finding out what proportion of genes have different alleles and how many alleles there are per gene.
How are monosaccharides joined together
By glycosidic bonds in condensation reactions
How can the brain determine the strength of the stimulus detected?
By interpreting -the frequency of action potentials arriving along the axon of sensory neurone AND -number of neurones carrying action potentials
How are hexose sugars e.g. glucose made?
By joining two triose phosphate molecules togehter.
How is gene expression regulated
By turning transcription on/off
Why do plants have a low RQ at times?
CO2 released in respiration is used up in photosynthesis
Continuous variation
CONTINUOUS VARIATION(quantitative variation) - when the individuals in a population vary within a range i.e. there are no distinct categories. e.g. humans have range of heights. • Inherited characteristics that show continuous variation are usually influenced by many genes - these characteristics = polygenic. E.g. human colour skin = polygenic as it comes in different shades of colour.
Differences between continuous and discontinuous variation
CONTINUOUS VARIATION: -Different alleles of the same gene locus have small effects on the phenotype. -Different genes have the same, often additive effect on one phenotype trait. -Large number of genes have a combined (additive) effect on a particular phenotypic trait; known as polygenes. DISCONTINUOUS VARIATION: -Different alleles of the same gene locus have large effects on the phenotype. -Different genes have quite different effects on the phenotype.
Solubility + Use of Ca(OH)2
Ca(OH)2 is quite soluble in water used to neutralise acidic salts Ca(OH)2 = limewater - test for CO2 - Ca(OH)2 + CO2 → CaCO3 + H2O - limewater turns cloudy
Why are greenhouse gases a problem for the environment?
Carbon dioxide, Water vapour and Methane from livestock and deforestation are mostly responsible for the greenhouse effect; which explains the rise in the average temperature as heat energy from the Sun is trapped in the Earth's atmosphere.
Why is the calvin cycle also called carbon fixation?
Carbon from CO2 is fixed into an organic molecule
How do sarcomeres return to their original relaxed states (longer) after stimulation of muscle?
Calcium ions leave binding site on troponin, and moved by active transport back into sarcoplasmic reticulum. Troponin shape changed, so pulls attached tropomyosin which once again block the actin-myosin binding sites. So muscles aren't contracted as myosin heads can't attach to actin. Actin filaments slide back to relaxed position, so sarcomere is lengthened.
What happens when muscle cells stop being excited?
Calcium ions leave their binding sites on the troponin molecules and are moved by active transport back into the sarcoplasmic reticulum. Troponin molecues return to their original shape, pulling the attached tropomyosin molecules with tem so tropomyosin molecules block the actin-myosin sites again. Muscles aren't contracted becasue no myosin heads are attached to actin filaments. The actin filaments slide back to their relaxed positions, which lengthens the sarcomere
Why is it important to know how much energy is involved during a reaction?
Can measure fuel energy values, can calculate energy requirements for industry, can find theoretical energy amounts for bond making and bond breaking, can predict if a reaction will take place or not
Leukaemia
Cancers of the stem cells in the bone marrow 1. The stem cell divide uncontrollably to give many immature white blood cells that do not differentiate properly. 2. This disrupts the production of normal blood cells, including blood cells. 3. These malignant cells fill up the bone marrow and then flow into the blood and into the lymphatic system. Leukaemia causes an increase in the white blood cell count, but these cells are abnormal as they are immature as they haven't differentiated properly.
Mean energy values of respiratory substrates
Carbohydrates - 15.8 Proteins - 17.0 Lipids - 39.4
Chiral Carbon
Carbon atom with four different groups attached
Facilitated diffusion by carrier proteins
Carrier proteins move large molecules into or out of the cell, down their concentration gradient. Different carrier proteins facilitate diffusion for different molecules: 1. Large molecule attaches to carrier protein in membrane. 2. Carrier protein changes shape. 3. This releases the molecule on the opposite side of the membrane.
What are Catalysts and how do they work?
Catalysts increase reaction rates without getting used up, by providing an alternative route or mechanism with a lower activation energy.
What is a catalytic converter?
Catalytic converters can help remove the three main pollutants from vehicle exhausts (nitrogen oxides, unburnt hydrocarbons and carbon monoxide) using transition metals such as rhodium and platinum which convert them into less harmful chemicals.
What is catalytic cracking?
Catalytic cracking makes mostly motor fuels and aromatic hydrocarbons. It uses a zeolite catalyst at a slight pressure and a high temperature of 450'C. Using a catalyst cuts costs because a lower temperature and pressure can be used. It also speeds up the rate of reaction.
Receptors
Cells or proteins on cell surface membranes that detect changes in stimuli. Many different types of receptors that detect different stimuli.
Benefit cellulose in cell walls
Cellulose has strong fibres (microfibrils) so it provides structural support for cells.
What are chain isomers?
Chain isomers are a type of structural isomer. They have different arrangements of the carbon skeleton. Some are straight chains and others are branched in different ways.
How does evolution occur?
Change in allele frequencies caused by: -Natural selection -Genetic drift -Founder effect
Genetic drift
Change in allele frequency that occurs by chance, because only some of the organisms of each generation reproduce.
Rate of reaction
Change in concentration of a substance with unit time.
Gene mutation
Change in the structure of DNA, producing a different allele of a gene
Chromosome mutation
Change in the structure or number of whole chromosomes in a cell
Evolution
Changes in a population that may lead to speciation or extinction OR Changes in the alle frequency within a population
How can the tertiary structure of an enzyme be changed
Changes in pH or temperature Mutation
Mutation
Changes in the base sequence of an organism's DNA.
Facilitated diffusion by channel proteins
Channel proteins provide hydrophilic passages through which the charged particles can diffuse through down their concentration gradient. Different channel proteins facilitate the diffusion of different molecules.
Meiosis process
Check one note Meiosis I: Reduction division, resulting in two daughter nuclei with half the number of chromosomes of the parent nucleus. Meiosis II: Chromosomes behave as in mitosis so that each of the two haploid daughter nuclei divides again. Therefore meiosis results in total of 4 haploid nuclei Human body cells are diploid, containing two complete sets of chromosomes, but meiosis produces gametes that are haploid, containing one complete set of chromosomes. Before meiosis begins, DNA replication takes place as it does before mitosis, so there are two copies of each chromosome.
b) explain, with examples, how environmental factors can act as stabilising, disruptive and directional forces of natural selection
Check text book
What are neurotransmitters?
Chemical messengers which transmit nerve impulses across synapses
Carcinogen
Chemical that can cause a cell to become cancerous
Carcinogens
Chemicals that can cause a cell to become cancerous
Antibiotics
Chemicals that can either kill or inhibit the growth of bacteria without harming the cells of the infected organism.
What is Propogation one of Methane?
Chlorine free radicals react with methane molecules, removing a hydrogen to create a methyl radical and hydrogen chloride.
Why do shallow pools need frequent addition of Chlorine?
Chlorine is rapidly lost due to the UV, so it frequently needs replacing.
Uses of haloalkanes
Chloro alkanes and chloro fluoro alkanes can be used as solvents, refrigerants and aerosol propellants
Different types of photosynthetic pigments
Chlorophyll (primary pigments): Chlorophyll a (yellow-green) Chlorophyll b (blue-green) Carotenoids (accessory pigments): B carotene (orange) Xanthophyll (yellow)
Photosynthetic pigments examples
Chlorophyll A Chlorophyll B Carotenoids
Why do most plants appear green?
Chlorophyll absorb mainly in the red and blue-violet regions. They reflect green light, making the plant look green.
Between chloroplasts and mitochondria, which is bigger?
Chloroplast
Which two components contribute to the fluidity of the plasma membrane?
Cholestrol Fatty acid chains of phospholipid molecule
What are synapses using acetylcholine called?
Cholinergic synapses
What receptor does the neurotransmitter acetylcholine (ACh) bind to?
Cholingernic receptors
Form of DNA during interphase
Chromatin
Colour of Chlorine and Chloride
Cl2 → Greenish gas Cl- → very pale green solution, almost colourless
Co-transporter process
Co-transporters are a type of carrier protein 1. They bind two molecules at a time. 2. The concentration gradient of one molecule is used to move the other molecule against its own concentration gradient.
Cohesion and tension
Cohesion and tension helps moves water up the plants, from roots to leaves against gravity: 1. Water evaporates from the leaves at the top of the xylem by transpiration. 2. This creates tension/transpiration pull (hydrostatic pressure gradient causing mass flow), which pulls water into the leaf. 3. Water molecules are cohesive, so when some pulled into leaf, others follow. 4. In this way the whole (continuous) column of water in xylem, from leaves down to roots is pulled up. (MASS FLOW OF WATER) 5. Water enters stem from roots.
Alternative for gas syringe
Collect gas in inverted measuring cylinder over water
Disdvantages of Recycling Metals
Collecting, Sorting and Transporting costs
What are photosynthetic pigments
Coloured substances found in the chloroplast that absorb light energy needed for photosynthesis.
Photosynthetic pigments
Coloured substances that absorb the light energy needed for photosynthesis
Colour of Al3+ metal aqua ion in soln
Colourless
Respiratory substrate
Complex organic molecules: Glucose Amino acids Fatty acids
Pulmonary system
Composed of the blood vessels taking blood away from from the heart to the lungs, and back.
Systemic system
Composed of the blood vessels taking blood away from the heart to the rest of the body, and back.
Carbohydrates
Compounds consisting of carbon, oxygen and hydrogen
What are Petrochemicals?
Compounds that can be converted into other chemicals, for use as solvents, paints and various other things.
Electrochemical gradient
Concentration gradient of ions
What is an electrochemical gradient?
Concentration gradient of ions
What calculations can be carried out based on the average titre?
Concentration. Number of Moles. Mass. Mr. Percentage Purity. Degree of hydration. Identity of unknown elements.
Peptide bond formation
Condensation reaction whereby H (NH2) atom of one amino acid bonds with OH (COOH) group of another, releasing a molecule of water. Bond formed between carboxyly group and amino groups of adjacent amino acids.
First Ionisation Energy down Group 2 Alkali Metals
Decreases down the group, Outer electrons are held successively further from the nucleus outer electrons are more shielded from the positive nucleus
Melting points of Group 2 Alkali Metals
Decreases down the group, due to increased atomic radius (more e- shells), weaker metallic bonding (electrostatic forces between positive ions and delocalised electrons weakens) lower charge density
Oxidising Strength of Group 7
Decreases down the group, due to reduced nuclear pull, weaker oxidising agent is displaced from solution by a stronger halide
Electronegativity down Group 7
Decreases, as atomic radii increases down the group, increasing number of shells, so reduced nuclear pull
How is the nature of a stimulus determined?
Deduced from position of the sensory neurone bringing the information
Biodiversity description
Degree of variation of life forms in an ecosystem. Includes diversity at three levels: 1. The variation in ecosystem or habitats 2. The number of different species in an ecosystem and their relative abundances. 3. The genetic variation within each species
How do we calculate Density?
Density = Mass/Volume
What are the properties of Diamond?
Diamonds carbon atoms are boned to four other carbon atoms. These are arranged in a tetrahedral shape. Diamond has a very high melting point and is very hard, it cannot conduct electricity due to all of its electrons being held in localised bonds. it can also not dissolve in a solvent.
What causes water to move up the xylem when transpiration occurs in the leaves
Difference in hydrostatic pressure at top and bottom of xylem
What keeps water in plants moving in the right direction from roots up to leaves
Difference in water potential between soil/roots and leaves. Water potential in roots is higher than in leaves, so water moves down the water potential gradient in this direction.
Genetic variation
Differences that exist between individuals' genetic material.
Variation in phenotype
Different species have different genes, but same species have same genes but different versions of them (alleles). Genes and alleles make up genotype - difference in genotype = variation in phenotype.
Types of passive transport
Diffusion Facilitated diffusion Osmosis
Diffusion
Diffusion is the net movement of particles (molecules and ions) from an area of higher concentration to an area of lower concentration/ down a concentration gradient.
What type of diseases are vaccines not effective against
Diseases that are not caused by pathogens e.g. Sickle cell anaemia
Strong acids and bases
Dissociate fully in water
Weak acids and bases
Dissociate partially in water
What is the solubility of Barium Hydroxide?
Dissolves easily in water. The Hydroxide ions present would make the solution strongly alkaline.
Genetic diversity
Diversity of alleles within the genes in the genome of a single species OR The range of genetic material present in a gene pool or population of a species.
Unidentate
Donates one electron pair
What happens to the First Ionisation Energy down a group?
Down a group, the first ionisation energy decreases because there is an increase in atomic radius and increased shielding and hence less nuclear attraction of the outer electron.
What is the trend of Melting points down a group 2?
Down the group the melting points decrease. The metallic bonding weakens as the atomic size increases. The distance between the positive ions and delocalised electrons increases, therefore weakening the electrostatic forces between positive ions and delocalised electrons.
What happens to excess tissue fluid
Drained into lymph vessels
Examples of substances that are transported by bulk transport
Droplets of liquid Bacteria
Prophylactic drugs
Drugs that prevent pathogens infecting and breeding inside a person
When are mutations most likely to occur
During DNA replication e.g. when wrong base slots into position in the new strand being built
Where are the radicals during a Free Radical Substitution Mechanism?
During Inititation, Free radicals are formed from no radicals. In Propagation (chain reaction), Free radicals are on both sides of the equation. In Termination, a combination of free radical molecules are formed.
How is an infra-red spectrum formed?
Each covalent bond absorbs a specific frequency of infrared, so when a range of infrared passes through an organic compound, some frequencies are absorbed. The resultant radiation is detected and converted into an infra-red spectrum.
How is the Skeletal Formula drawn?
Each covalent bond is shown by a line. A carbon atom is at the join of lines. Functional groups are shown. The number of hydrogen atoms on each carbon atom is the difference between the number of lines and 4. It is generally used for larger organic molecules.
What does a mass spectrum chart show?
Each line represents a different isotope of an element. the height of each peak gives the relative isotopic abundance (the amount of it). For a molecular substance the peak with the greatest m/z ratio corresponds to the Mr.
Why is it called semi-conservative DNA replication
Each new DNA molecule formed has one strand from the original DNA molecule and one new strand.
How would you distinguish between each of the Halides?
Each of the silver Halides have different solubilities in Ammonia.
Why is the interaction between antigens and antibodies specific?
Each type of antibody recognises a unique fragment of the antigen
Transport protein specificity
Each type of transport protein only allows one type molecule or ion to pass through it
Why is species diversity important?
Ecosystems with high species diversity are more stable and are more able to resist change
What coordinates the rhythmic contractions of the cardiac muscle in different parts of the heart
Electrical impulses passing through the cardiac muscle tissue.
What is the elctron transport chain made up of?
Electron carriers
What are photosystems in the thylakoid membrane linked by?
Electron carriers - proteins that transfer electrons
What are the 5 processes of Time-of flight mass spectrometry?
Electron impact or Electrospray ionisation; to form gaseous positive ions. Acceleration to constant kinetic energy. Ion drift. Ion detection. Data analysis.
Electrophile
Electron pair acceptor
What are the two main processes involved in oxidative phosphorylation?
Electron transport chain Chemiosmosis
What is the combination of the photosystems and electron carriers called?
Electron transport chain - a chain of proteins through which excited electrons flow
What is electron pair repulsion theory?
Electrons are all negatively charged, so the charge clouds will repel each other as much as they can. The shape of the cloud charge affects how much it repels other charges. Lone pair charge clouds repel more than bonding-pair charge clouds.
Why are Transition metal complexes coloured?
Electrons in d orbital absorb UV light. The more UV light absorbed the bigger the gap in energy of the electrons. Some gain enough energy to move up to the next energy level. I.E the electrons have different amounts of energy. They absorb different wavelengths of light.
What did Bohr's atom model show?
Electrons only exist in fixed orbits and not anywhere in between. Each Shell has a fixed energy. When an electron moves between shells, electromagnetic radiation is emitted or absorbed. Because the energy of the shells is fixed, the radiation will have a fixed energy.
What is electrostatic attraction?
Electrostatic attraction holds positive and negative ions together - it is very strong.
Types of bulk transport
Endocytosis Exocytosis
Endothermic Reactions
Energy is taken up from the surroundings to the system, energy is needed to break bonds more than is released when the bonds are formed, so energy input is required to proceed. Products have more energy than reactants ∆H = positive (as energy is added to the system)
Why does only glycolysis occur in anaerobic respiration?
Energy releasing reactions of the Krebs cycle and oxidative phosphorylation need oxygen.
Exothermic Reactions
Energy's transferred from the system to the surroundings. The energy needed to break bonds is less than the energy released when bonds are formed. Products have less energy than reactants ∆H = negative (as energy is lost from the system)
Lattice Dissociation Enthalpy
Enthalpy change to separate 1 mol of an ionic substance into its gaseous ions
Lattice Formation Enthalpy
Enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions.
Electron Affinity
Enthalpy change when 1 mole of gaseous atoms Form 1 mole of gaseous negative ions
Enthalpy of Solution
Enthalpy change when 1 mole of solid dissolves in water to form aqueous ions
Catabolic reaction
Enzyme catalyses a breakdown reaction: when the substrate fits into the active site, it puts a strain on the bonds in the substrate, so the substrate molecule breaks up more easily
Substrates combine with enzymes to form
Enzyme substrate complex
Carbonic anhydrase
Enzyme that converts carbon dioxide into carbonic acid in red blood cells.
Restriction endonuclease
Enzyme.. -originally derived from bacteria -which cuts DNA at a specific site (recognition site) -leaving sticky ends. Destroys viral DNA in bacteria.
What does the stroma contain
Enzymes Sugars Organic acids
Le Chatelier's Principle
Equilibrium will shift to oppose any change imposed on it by the external environment
Prevention and control of smallpox
Eradicated by 1979, through vaccination campaign.
Difference in DNA of eukaryotic and prokaryotic cells
Eukaryotes: Longer linear DNA, found in nucleus, exists as chromosomes. Prokaryotes: Shorter circular DNA, free-floating in cytoplasm, naked DNA (not associated with any histones)
Transpiration
Evaporation of water from the leaves of a plant.
What does changes in allele frequency lead to?
Evolution
Structure of Haemoglobin
Fe2+ with Porphyrin (4x N bonds), One globin protein and one bond to either O2 or H2O.
Huntington's disease description
Example of mutation that is inherited as a dominant allele. Neurological disorder resulting in: -Involuntary movements -Mental deterioration (brain cells lost and ventricles in brain enlarge) Age of onset varies - most common for middle aged people. Mutation is an unstable segment in a gene on chromosome 4 coding for protein HUNTINGTIN. NO HD: Segment made up of small number of repeats of triplet of bases CAG. HD: Segment made up of large number of repeats of triplet bases CAG. These are called stutters The more the number of repeats of CAG triplet i.e. more stutters = earlier age of onset
What mechanism is used when glucose enters the cell?
Facilitated diffusion
Limiting factor
Factor with greatest effect in reducing the rate
Difference between fibrous and globular proteins
Fibrous protein: 1. Long strands 2. Insoluble in water 3. Long polypeptide chains with cross links Globular proteins: 1. Spherical shape 2. Soluble in water 3. Tightly folded into spherical shape
What would be observed if Carbonate was present?
Fizzing due to the Carbon Dioxide.
What are flexors and extensors?
Flexor: Muscle that bend joints when it contract Extensor: Muscle that straightens joints when it contracts
Thylakoids
Fluid filled sacs found in the chloroplast Stacked up to form Grana Grana linked together by bits of thylakoid membranes called lamellae
Tissue fluid
Fluid that surrounds cells in tissue
Tissue fluid
Fluid that surrounds cells in tissues. It's made of substances that leave the blood e.g. oxygen, water and nutrients.
What is percentage yield and what is its formula?
For any reaction the actual mass of the product (actual yield) will be less than the theoretical yield. percentage yield = actual yield / theoretical yield x 100
Why is ATP produced during interphase
For the energy needed for cell division
What are functional group isomers?
Functional group isomers area type of structural isomer. They have the same atoms arranged into different functional groups.
Function of phospholipids
Form the bilayer of cell membranes
How are the mesophyll cells arranged in C4 plants to exclude air from bundle sheath cells>
Form tight ring around bundle sheath cells
How do nucleotides link together
Formation of covalent bonds between the phosphate group of one nucleotide and the sugar of another by a condensation reaction. (Sugar phosphate back bone formed)
Oogenesis
Formation of femal gametes
Spermatogenesis
Formation of male gametes
Collagen functions
Forms supportive tissue in animals: 1. structure of bones 2. makes up cartilage and connective tissue 3. main component of tendons, which connect skeletal muscles to bones
Multidentate
Forms two or more co-ordinate bonds
Plasmodesmata
Found in cell walls, allowing exchange of substances between adjacent cells by linking cytoplasm of adjacent cells
Goblet cells function
Found in ciliated epithelium: They secrete mucus which traps microorganisms/pathogens and dust particles in inhaled air, stopping them from reaching the alveoli.
Mucous glands
Found in the goblet cells. They secrete the mucous.
Elastic fibres
Found in the walls of all tubes and between the alveoli. They help with the process of breathing out: - When breathing in, the fibres stretch, allowing the airways and alveoli to expand. - When breathing out, they recoil, helping to push the air out.
Cartilage function
Found in the walls of the trachea and bronchi: 1. Provides support 2. Prevents the tube collapsing when the air pressure inside them is low when breathing in. 3. Keep the airway open
Smooth muscle
Found in the walls of the trachea, bronchi and bronchioles: - Contracts and relaxes to control the diameter of the tubes/airways to be controlled. - It can contract for long periods of time without tiring. - During exercise the smooth muscle relaxes, widening the tubes, so there is less resistance to air, so more air can reach the lungs.
Ciliated epithelium function
Found lining the trachea, bronchi and some bronchioles: Single layer of cells whose outer surfaces are covered in cilia which beat the mucus, moving it along with the trapped dust particles and microorganisms upwards towards the mouth, helping to prevent dust particles and microorganisms/pathogens from reaching the lungs.
What is the Mechanism of Chlorination?
Free-radical substitution.
Synapctic cleft
Gap between two neurones about 20 nm wide
Vertical gene transmission
Genes are passed on during reproduction: 1. Bacteria reproduce asexually, so each daughter cell is an exact copy of the parent. 2. This means that each daughter cell has an exact copy of the parent cell's genes, including any that give it antibiotic resistance. 3. Genes for antibiotic resistance can be found in the bacterial chromosomes or in plasmids (rings of DNA). 4. The chromosome and any plasmids are passed on to the daughter cells during reproduction.
Sex linked genes
Genes that are carried on an X chromosome but not a Y chromosome
How does the environment affect the phenotype of plants and animals?
Genetic factors determine the genotype and the characteristics an organism is born with, but environmental factors affect the way in which these characteristics develop. Most phenotypic variation is caused by combination of genotype and environmental factors = CONTINUOUS VARIATION E.g. HEIGHT OF PEA PLANTS: -Due to genotype can be either tall or dwarf form (discontinuous variation) -Exact height of tall or dwarf form varies (continuous variation) due to environmental factors such as light intensity. HUMAN BODY MASS: Partly genetic, but strongly influenced by diet and exercise. Human body bass varies within a range = continuous variation. Despite same genotype, one individual might have more food available causing greater body mass.
What is variation in phenotype caused by?
Genetic variation Environment
Apoplast pathway
Goes through non-living parts of cells. Water seeps into cell wall, and moves into and along cell walls of neighbouring cells. OR diffuses through the cell walls and passes through the spaces between them.
Action spectra
Graph showing rate of photosynthesis at different wavelengths of light.
Absorption spectra
Graph showing the absorption of different wavelengths of light by the various pigments found in chloroplasts.
Heterozygous
Genotype having different alleles of a gene
What are giant covalent structures
Giant covalent structures have huge networks of covalently bonded atoms. Carbon often forms this type of structure because they can each form four strong covalent bonds.
Vaccination
Giving a vaccine containing antigens for a disease, either by injection or by mouth; vaccination provides artificial active immunity.
What are glands and hormones?
Glands: Group of cells specialised to secrete a useful substance, such as a hormone (e.g. pancreas secretes insulin) Hormone: Substance secreted by glad which acts as chemical messenger
What type of proteins are enzymes
Globular proteins
How does glucagon raise the blood concentration when it's too low?
Glucagon binds to specific receptors on cell surface membranes of liver cells: 1. GLYCOGENOLYSIS - glucagon activates an enzyme that breaks down glycogen into glucose. 2. GLUCONEOGENESIS - promotes formation of glucose from noncarbohydrates (amino acids/fatty acids) 3. Decreases rate of respiration in cells.
Examples of useful organic substances produced using triose phosphate?
Glucose Proteins Lipids Nucleic acids
Aerobic respiration equation
Glucose + Water -> Carbon Dioxide + Water + Energy
What is glycogenesis, glycogenolysis and gluconeogenesis?
Glycogenesis: Formation of glycogen from glucose Glycogenolysis: Breakdown of glycogen to glucose Gluconeogenesis: Formation of glucose from noncarbohydrates (i.e. fatty acids/amino acids -> glucose)
Symplast pathway
Goes through living parts of cells. Water moves down a water potential gradient through plasmodesmata which connect the cytoplasms of neighbouring cells.
What are the properties in Graphite?
Graphite has carbon atoms arranged in sheets of flat hexagons bonded with three bonds each. The fourth outer electron of each carbon is delocalised. The sheets of hexagons are bonded together by Van der Waals forces. Graphites weak bonds means that the layers can easily slide over one another, used in pencils and lubricants. It can also conduct electricity due to its delocalised electrons that are free to move along the sheets. It has a very high melting point due to the strong covalent bonds in the hexagon sheets. It is also insoluble.
Effect of wind on transpiration rate
Greater wind speed = increased rate. Lots of air movement carries away the water vapour from around the stomata/leaf surface. This increases the water potential gradient between air spaces in the leaf and the air outside, therefore increasing the rate of transpiration as water vapour diffuses out of the leaf more rapidly.
Colour of Fe2+ metal aqua ion in soln
Green
What flame colour is Barium?
Green
What is a gland?
Group of cells which are specialised to produce and release one or more substances. e.g. hormones
Codon
Group of three nucleotide bases in mRNA that codes for a particular amino acid.
Mechanisms used by mammals to change body temperature
HEAT LOSS 1. Sweating 2. Lowering body hairs 3. Vasodilation HEAT PRODUCTION 1. Shivering 2. Hormones (adrenaline secretion) HEAT CONSERVATION 1. Decreased sweat production 2. Raising body haris 3. Vasoconstriction
Mechanisms used by mammals to change body temperature description
HEAT LOSS 1. Sweating: Sweat glands increase production of sweat which evaporates on surface of skin so removing heat from body. 2. Lowering body hairs: Mammals have layer of hair providing insulation by trapping air (air = poor conductor of heat) Muscles attached to hairs (pili erector muscle) relax, so lie flat, so less air trapped = reduction of layer of insulation. Skin less insulated and heat can be lost more easily. 3. Vasodilation: Muscles in walls of arterioles that supply blood to capillaries near surface of skin relax, so arterioles dilate (lumen widened), allowing more blood to flow through capillaries so heat is lost from skin to surrounding by radiation. HEAT PRODUCTION 1. Shivering: Involuntary contractions of skeletal muscles, increases respiration = heat produced. Heat absorbed by blood and carried around rest of the body. 2. Hormone (adrenaline secretion): Increase metabolism = increased rate of heat production in liver. HEAT CONSERVATION 1. Decreased sweat production: Less sweat secreted from sweat glands, so reducing loss of heat by evaporation from skin surface. 2. Raising of body hairs: Pili erector muscle contracts, making haris stand up - more air trapped = greater layer of insulation = prevents heat loss. 3. Vasoconstriction: Muscles in walls of arterioles that supply blood to capillaries near surface of skin contract, so arterioles constrict , allowing less blood to flow through capillaries so less heat is lost from skin to surrounding by radiation.
Negative feedback control of blood glucose concentration
HIGH GLUCOSE CONCENTRATION 1. Receptors: a + B cells in islets of langerhans detect rise in blood glucose. 2. Less glucagon and more insulin secreted. 3. Effectors: -Liver cells respond to less glucagon = no glycogen breakdown -Muscle, liver and fat cells respond to more insulin = increased uptake of glucose and conversion to glycogen LOW GLUCOSE CONCENTRATION 1. Receptors: a + B cells in islets of langerhans detect fall in blood glucose. 2. More glucagon and less insulin secreted. 3. Effectors: -Liver cells respond to more glucagon = glycogen breakdown -Muscle, liver and fat cells respond to less insulin = decreased uptake of glucose and conversion to glycogen
Identification of Halide + H2SO4 products
HX → white steamy fumes Br2 → red fumes SO2 → colourless acidic gas H2S → bad eggy smell S → yellow solid I2 → purple fumes/black solid
Feature of haemoglobin belonging to organisms living in environments with a low concentration of oxygen
Haemoglobin has higher affinity for oxygen than humans. Curve is to the left of humans'q
Feature of haemoglobin belonging to active organisms with a high oxygen demand
Haemoglobin has lower affinity for oxygen than humans. Curve is to the right of humans'
0% saturation of haemoglobin with oxygen
Haemoglobin is carrying 0 oxygen molecules
100% saturation of haemoglobin with oxygen
Haemoglobin is carrying 4 oxygen molecules
Homozygous
Having two identical alleles of a gene
Normal form of haemoglobin
HbA
What is Hb^S and Hb^A?
Hb^S= Allele for normal B-globin polypeptide Hb^A= Allele for sickle cell B-globin polypeptide
Why can't a boy inherit a sex linked gene from his father?
He only gets a Y chromosome from his father. X chromosome carrying the sex-linked gene comes from the mother.
Calorimeter: Errors in method
Heat loss, Incomplete fuel combustion, incomplete heat transfer, evapouration of fuel after weighing, measurements are sometimes not under standard conditions, heat capacity of calorimeter isn't included
How do we calculate the degree of hydration?
Heating a hydrated compound to constant mass produces an anhydrous compound. The simplest ratio of the number of moles of the anhydrous compound to the number of moles of water determines the degree of hydration.
Reflux
Heatly reaction mixture for long periods, organic vapours are condensed to liquids so they don't escape, condenser isn't sealed to prevent pressure build up and explosion - used for oxidation of aldehydes and secondary alcohols
Shape of amylose
Helical
Benefits of reflex actions
Help organisms avoid damage to the body as they're rapid.
Root pressure
Helps to move water up the xylem. When water transported into xylem in the roots, it creates a pressure and shoves water already in the xylem further upwards. OR 1. Caused by active transport of ions into root cells. 2. This causes water to get into root tissue via osmosis from soil. 3. This will cause root cortex to get very turgid. 4. Creates pressure that pushes water up the xylem vessels.
Ester bond formation
Hydrogen atom on the glycerol molecule bonds to a hydroxyl group on the fatty acid, releasing a molecule of water (condensation reaction)
What is hydrogen bonding?
Hydrogen bonding is the strongest intermolecular force. it only happens when hydrogen is covalently bonded to fluorine, nitrogen or oxygen because they're very electronegative and can pull the bonding electrons away from the hydrogen. Substances with hydrogen bonding have higher melting and boiling points because of the extra energy needed to break the hydrogen bonds.
Complementary base pairing
Hydrogen bonding only occurs between particular pyrimidines and purines. Adenine & Thymine/Uracil. Cytosine & Guanine. (Each base can only join with a particular base)
Temperature affects ________ _______ hence if the temperature gets too high, the enzymes are denatured
Hydrogen bonds
What bonds in enzymes are affected by extreme pH values?
Hydrogen bonds Ionic bonds
How is the DNA double-helix formed
Hydrogen bonds are formed between the bases of the two DNA strands and they wind up around each other.
A DNA molecule is made up of two strands held together by....
Hydrogen bonds between the bases on the two strands.
Why are water molecules cohesive
Hydrogen bonds exist between water molecules
How is the Relative rate of reaction of the Halogens tested?
Hydrolyse a sample of each. The appearance of a precipitate indicates a reaction has occured. Prepare a water bath using a large beaker and Bunsen. Add Anti bumping granules. Add silver nitrate. Add 5/6 drops of each halogenoalkane to the silver nitrate. Heat the test tube to 60'C.
Breaking of peptide bond
Hydrolysis reaction: Molecule of water added, breaks peptide bond
How do you test for Halide Ions using Silver Nitrate?
If Silver Ions are added to solutions of Halide Ions (except Fluorine), a precipitate of the Silver Halide is produced.
What is Le Chatelier's principle?
If an external condition is changed, the equilibrium will shift to oppose the change and therefore try to reverse it.
How do pathogens get into the body through the skin
If you damage your skin, pathogens on the surface can enter your bloodstream.
Why is Nitric Acid added before the Silver Nitrate?
In order to remove the Carbonate or Hydroxide ions which are insoluble and would give a false-positive result.
Purine bases
Made of two carbon-nitrogen rings: 1. Adenine 2. Guanine
Stimulating muscles to contract process
Impulse moves along axon of motor neurone and action potential arrives at the presynaptic membrane. Action potential causes diffsuion of calcium ions into neurone. The calcium ions cause vesicles containing acetylcholine to fuse with presynaptic membrane. Acetylcholine released and diffuses across synaptic cleft. Acetylcholine molecules bind with receptors in sarcolemma, causing them to open channel proteins for sodium ions. Sodium ions diffuses through open channels in sarcolemma - depolarsises membrane and initiates action potential which spreads along the membrane. Action potential passes along sarcolemma and along T-tubulses to sarcoplasmic reticulum. Channel proteins for calcium ions on sarcoplasmic reticulum open and calcium ions diffuse out into sarcoplasm. Caclium ions bind with troponin, causing it to change shape, moving the attached tropomyosin molecules to expose myosin-binding sites on actin filament. Myosin heads attach to binding sites on actin and from cross-bridges. When no longer any stimulation from motor neurone, there are no impulses conducted along T-tubules. Calcium ion channels in SR close and calcium pumps move calcium ions back into stores in SR. As calcium ions leave binding sites on troponin, tropomyosin move back to cover myosin-binding sites on actin. No cross-bridges between thick and thin filaments = muscle in relaxed state Nothing holding the two filaments togeter so any pulling force applied to muscle will lengthen sarcomeres so ready to contract again.
Albinism description
In albinism the dark pigment melanin is totally or partially missing from the skin, hair and eyes leading to: -very pale skin and hair -pale blue or pink irises -red pupils -poor vision -rapid jerky movements of eyes The mutation is autosomal recessive so individuals homozygous for the recessive allele show albinism. Mutation in gene coding for the enzyme tyrosinase results in: -absence in tyrosinase -presence of inactive tyrosinase in melanocytes (cells responsible for melanin production) Tyrosine (+tyrosinase)-> DOPA (+tyrosinase) -> Dopaquinone -> Melanin Due to absence of tyrosinase the first two steps of conversion of the amino acid tyrosine to melanin can't occur i.e. tyrosine can't be converted into DOPA and dopaquinone THEREFORE melanin cannot be produced.
What is a covalent bond?
In covalent bonding, two atoms share electrons, so they've both got full outer shells of electrons. Both the positive nuclei are attracted electrostatically to the shared electrons.
How are the hydrogen bonds in ice held together?
In ice, there are 2 ordinary covalent bonds and the 2 hydrogen bonds are more ordered and hold the molecules in fixed positions in a three dimensional tetrahedral lattice, so the water molecules are held closer together than in a liquid. The more open arrangement means that ice has a lower density than water.
Where are the photosynthetic pigments found?
In thylakoid membranes attached to proteins
How does lactate fermentation and alcoholic fermentation differ?
In which organisms they occur and what happens to the pyruvate produced in glycolysis
Passive natural immunity
In young babies, acquires antibodies form it's mother's breast milk.
What is the effect of Temperature on Equilibrium?
Increase - The equilibrium will shift to oppose this and move in the endothermic direction to try and reduce the temperature by absorbing heat. Decrease - The equilibrium will shift to oppose this and move in the exothermic direction to try and increase the temperature by giving out heat.
Effect of substrate concentration on rate of reaction when all active sites are full
Increase in substrate concentration has no further effect on rate of reaction.
Effect of light intensity on transpiration rate
Increase light intensity = increased rate High light intensity causes plant to photosynthesise rapidly, so requires a rapid supply of CO2. So more stomata likely to be open, through which water vapour can diffuse out of the leaf.
Why is the bit of the root that absorbs water covered in root hairs
Increase surface area of the root in order to increase the rate of water uptake.
Respirometer
Instrument which measures the rate of oxygen being taken up.
Hormones involved in blood glucose concentration regulation
Insulin and glucagon secreted by clusters of cells in pancreas called Islets of Langerhans: -Glucagon secreted by alpha cells -Insulin secreted by beta cells Insulin and glucagon act on effectors, which respond to restore the blood glucose concentration to normal level.
How does insulin lower blood concentration when it's too high?
Insulin binds to specific receptors on cell surface membranes of liver, muscle and fat cells: 1. Increases permeability of cell surface membrane to glucose so cells take up more glucose. 2. GLYCOGENESIS - insulin activates an enzyme that converts glucose to glycogen. Glycogen stored in cytoplasm as an energy source. 3. Increases rate of respiration of glucose, especially in muscle cells.
Which cells respond to insulin and glucagon?
Insulin: Liver, muscle and fat cells Glucagon: Liver cells
What is ionic bonding?
Ionic bonding is bonds that have electrostatic attraction. When oppositely charged ions form an ionic bond you get an ionic compound.
Bonds in tertiary and quaternary structures
Ionic bonds Disulfide bonds Hydrophobic and hydrophilic interactions Hydrogen bonds
What is the electrical conductivity of an ionic compound?
Ionic compounds conduct electricity when they're molten or dissolved - but not when they're solid. The ions in a liquid are free to move and carry a charge. In a solid they're in a fixed position by the strong ionic bonds.
What is the melting point for ionic compounds?
Ionic compounds have high melting points. The giant ionic lattices are held together by strong electrostatic forces. It takes lots of energy to overcome these forces, so melting points are very high.
What is the solubility of ionic compounds?
Ionic compounds tend to dissolve in water. Water molecules are polar - part of the molecule has a small negative charge and the other bits have small positive charges. The water molecules pull the ions away from the lattice and cause it to dissolve.
Perfect Ionic Model
Ions can be regarded as perfect spheres
What metals can be extracted using Carbon
Iron (Fe2O3), Manganese (MnO2) and Copper (CuCO3)
What are isotopes?
Isotopes of an element are atoms with the same number of protons but different numbers of neutrons
Why does carotenoid appear orange?
It absorbs mostly violet, blue and green light in sunlight so, yellow orange and yellow is reflected.
How do you calculate the Relative molecular mass of a compound?
It can be determined by looking for the peak with the largest m/z value (the molecular ion peak).
What is meant by "Acting as an Acid?"
It donates a Hydrogen.
How problematic is Methane compared to Carbon dioxide?
It has 20 times the effect.
What is the arrangement of Macromolecular substances, such as Graphite?
It has a Planar arrangement of carbon atoms in layers. There are 3 covalent bonds per carbon in each layer. The 4th electron is delocalised between the layers.
What is the arrangement of Macromolecular substances, such as Diamond?
It has a Tetrahedral arrangement of carbon atoms, with 4 covalent bonds per carbon.
Why does Mg deviate from the general trend?
It has a different crystalline structure.
What is the effect of a Catalyst on equilibrium?
It has no effect on the position of equilibrium, but it will speed up the rate at which the equilibrium is achieved; by speeding up the rates of the forward and backward reactions by the same amount.
Why does the apoplast pathway carry the most water
It has the lease resistance
What is the importance of Fractional distillation?
It increases the quantity of economically important or demanded fractions. Alkenes are produced, which are important feedstock chemicals. When unseparated, crude oil has limited uses.
What is the arrangement of Ionic substances, such as Sodium Chloride?
It is a Giant Ionic lattice, showing alternate Na+ and Cl- ions.
What is Crude Oil?
It is a mixture composed mainly of straight and branched chain alkanes, including lesser amounts of cycloalkanes and arenes (carbon rings).
What is a Chemical equation?
It is a symbolic representation of a chemical reaction, informing us of the reactants used and products formed.
Why is Titanium useful?
It is abundant, has a low density and is corrosion resistant.
What are the uses of Sodium Chlorate (NaClO)?
It is an oxidising agent and an Active ingredient in household bleach.
What happens in cyclic photophosphorylation?
It is called cyclic as electrons from the chlorophyll molecule aren't passed onto NAD, buta are passed back to PSI via electron carriers. So electrons are recycled and repeatedly flow through PSI. No reduced NADP or O2 produced - just small amounts of ATP
Why is TiO2 converted to TiCl4?
It is converted so that it can be purified by fractional distillation. The TiCl4 is Molecular, so is a liquid at room temperature rather than Ionic (solid).
Why is the light dependent reaction not affected too greatly by temperature?
It is driven by light energy not heat energy
What is a Dative Covalent (Coordinate) Bond?
It is formed when the shared pair of electrons come from only one bonding atom. (A lone pair of electrons becomes a bonding pair of electrons which is represented by an arrow).
Why is the ammonia produced from deamination immediately converted to urea?
It is highly toxic and soluble - so could rapidly build up in the blood and cause immense damage.
What is the solubility of Magnesium Hydroxide?
It is insoluble in water. A suspension of Magnesium Hydroxide in water will appear slightly alkaline (pH 9) so some Hydroxide ions must therefore have been produced by a very slight dissolving.
What makes up a double bond?
It is made of a Sigma bond (2 overlapping S-orbitals) and a Pi bond (2 overlapping P-orbitals). Sigma bonds are shorter and therefore stronger. Pi bonds are longer and weaker, making them easier to break - which explains the high reactivity. The double bond has restricted rotation, resulting in Alkenes exhibiting stereoisomerism.
What is an Ionic bond?
It is the Electrostatic attraction between oppositely charged ions, caused by electron transfer.
What is the oxidation state of a simple ion?
It is the same as the charge on the ion.
What is Titanium used for?
It is used for making strong yet light alloys for use in aircraft. Despite being abundant and useful, the extraction process is expensive and therefore it is used to a limited amount.
What are the uses of Chlorine Water?
It is used in drinking water and swimming pools as Chloric (I) Acid is an oxidising agent that kills bacteria by oxidiation.
What are the uses of Magnesium Hydroxide?
It is used in medicine (in suspension as Milk of Magnesia) to neutralise excess stomach acid and treat constipation. It is safe to use because it is so weakly alkaline and is preferable to using Calcium Carbonate as it will not produce Carbon Dioxide gas.
What are the uses of Barium Sulphate?
It is used in medicine as a "Barium Meal," given to patients who need x-rays of their intestines. The Barium is a Radiocontrast agent so absorbs the x-rays and shows the gut on the x-ray image. Despite Barium compounds being toxic, it is safe to use due to its low solubility.
During a titration, why do we use an indicator?
It is used to determine the exact point when the acid has neutralised the base, or vise versa. Two common indicators and phenolphthalein and methyl orange.
Why does lymph have the highest density of white blood cells compared to blood plasma and tissue fluid
It passes through the lymphatic glands where white blood cells accumulate.
What are the main products of Thermal cracking?
It produces a larger proportion of alkenes (usually Ethene) in addition to shorter straight chain alkanes.
What are the main products of Catalytic cracking?
It produces more branched chain alkanes and (aromatic) arenes (cyclic alkenes). Fewer alkenes are produced.
Why does the apoplast pathway carry the most water?
It provides the least resistance
Why is light still required in order for the light independent reaction to occur?
It relies on products (reduced NADP and ATP) from the light dependent reaction
What is meant by "acting as a Base?"
It removes a hydrogen.
What does an ionic equation show?
It shows both the oxidation and reduction with no electrons. The half-equations are balanced by multiplying the equations to give each the same number of electrons in each half-equation.
What is the Molecular Formula?
It shows the actual numbers of atoms of each element in a molecule.
What is the Molecular Formula?
It shows the exact number of atoms of each element in a compound.
What is the Empirical Formulae?
It shows the relative numbers of atoms of each element, essentially being the smallest whole number ratio.
What is the Displayed Formula?
It shows the relative positioning of atoms and the number of bonds between them.
What is the Empirical Formula?
It shows the simplest whole number ratio of atoms of each element in compound.
What is the Skeletal Formula?
It shows the simplified organic molecule's formula; removing hydrogen atoms, leaving just a carbon skeleton and associated functional groups.
What determines the properties and functions of a protein
It's three dimensional shape
Conditions for Nucleophillic Substitution to produce nitriles
KCN dissolved in ethanol or water heat under reflux
Conditions for Nucleophillic Substitution to produce alcohols
KOH or NaOH in aqueous solution, heat under reflux
Conditions for Elimination to produce alkenes
KOH or NaOH in ethanol, heated
Ionic Product of Water
Kw = [H+][OH−]
Types of systematic sampling
LINE TRANSECT: -Tape measure placed along transect. -Sample organisms that are present along the transect by recording identity of organism at set distances Transects used to detect changes in the community composition along a line across one or more habitats. BELT TRANSECT: -Quadrat is placed along the transect line at regular intervals.
Enzyme involved in the conversion of lactate to pyruvate and back
Lactate dehydrogenase
Types of anaerobic respiration
Lactate fermentation Alcoholic fermentation
What are skeletal muscles made up of?
Large bundles of long cells = muscle fibres
Examples of particles that can't diffuse through the plasma membrane
Larger molecules (e.g. amino acids, glucose) Charged atoms (e.g. chloride ions)
How can transect line be represented?
Lay out measuring tape
Squamous epithelium
Layer of thin, flat cells forming alveolar walls.
How is incomplete combustion a problem?
Less energy is released by incomplete combustion than by complete combustion. Carbon monoxide is a pollutant - it is absorbed by the blood in place of oxygen and hence reduces the ability of the blood to carry oxygen, causing suffocation or death. Carbon particles can cause breathing difficulties and cancer.
In C4 plants, where do the light dependent/independent reactions occur?
Light dependent: Mesophyll cells Light independent (Calvin cycle): Bundle sheath cells
What happens in the light dependent reaction?
Light energy is absorbed by photosynthetic pigments and converted to chemical energy -Light energy used to add a phosphate group to ADP to form ATP and to reduce NADP to form reduced NADP.
Factors that can limit photosynthesis
Light intensity Temperature CO2
Photorecepors
Light receptors in eyes
Substance made when [Co(H2O)6]2+ reacts with sodium carbonate
Lilac ppt CoCO3
Transect
Lines along which samples are taken by either: -noting species at equal distances (line transect) -placing quadrats at regular intervals (belt transect)
Relative energy content of lipids and carbohydrates
Lipids contain about twice as much energy per gram due to their hydrocarbon tails
Phospholipid adaptation
Lipids found in cell membranes: Fatty acid chains = hydrophobic Phosphate group = hydrophilic So in water, a group of phospholipid molecules arrange themselves into a bilayer with the hydrophilic heads facing outwards into the water and the hydrophobic tails facing inwards, avoiding contact with water
Plasma
Liquid component of blood
What is the mechanism of Catalytic cracking?
Long chain alkanes fit into the pores of the zeolite and are temporarily held in place before cracking.
Chromosomes
Long thread like structures composed of DNA associated with histone proteins that carry the genetic information of an organism
Glycogen structure
Long, branched chain of alpha-glucose. Similar structure to amylopectin, but has much more side branches.
Xylem vessels
Long, hollow tubes through which water moves by mass flow from the roots to the other parts of the plant.
Reducing Agent
Loses electrons
Oxidation
Loss of electrons
Effect of low pO2 (respiring tissue) on saturation of haemoglobin with oxygen
Low partial pressure =haemoglobin has low affinity for O2 =releases O2 rather than combining with it =Hb has low saturation of O2
How can a low water supply affect the rate of
Low water leads to closing of stomata to reduce water loss. So preventing CO2 from entering the leaf.
Effect of humidity on transpiration rate
Lower humidity = increased rate. Lower humidity means steepness of water potential gradient between air spaces inside the leaf and the air outside is greater, so water diffuses out of the leaf more rapidly.
What does the enzyme substrate do
Lowers the activation energy
Examples of non-infectious diseases
Lung cancer Sickle cell anaemia
Tissue fluid in the lymph vessels
Lymph
Lymphoblastic leukaemia
Lymphoid stem cells = cancerous 1. Immature white blood cells (haven't differentiated properly) = disrupts normal balance of components in the blood. - Body does not have enough red blood cells and platelets - Anaemia + excessive bleeding. 2. Number of neutrophils and lymphocytes decreases as many immature cells that do not differentiate properly are produced. So people with these cancers are more susceptible to infections (IMMUNO SUPRESSED)
Present in animal cells but not plant cells
Lysosomes Centrioles
Random sampling description
METHOD: -Divide area into grid using measuring tapes. -Use random number generator to select coordinates of sampling point in relation to grid marked out. -Coordinate = sampling point -Take sample of population (e.g. using quadrat) and repeat process to get more reliable estimate for whole area. Results can be used to calculate species frequency and density. For species such as grass, percentage cover of the species within the quadrat is measured.
Structure of myelin sheath
Made up of Schwann cells which wrap themselves around the axon of a neurone. 1/3 of motor and sensory neurones are myelinated. The myelin sheath provides electrical insulation around the axon, which greatly increases speed of transmission of action potentials.
Adaptation of structure of glucose
Main energy source in animals and plants: -soluble = easily transported -chemical bonds contain lots of energy
Starch
Main energy storage material in plants: Cells get energy from glucose, excess glucose is stored as starch. When in need of more glucose for energy, it breaks down the starch to release glucose.
Cellulose
Major component of cell walls in plants
Global pattern of malaria
Malaria is found in parts of the world where the Anopheles mosquito species that can act as a vector are found. -This is mostly in tropical and subtropical regions where humidity is high, providing ideal conditions for breeding of mosquitoes.
Where are male and female gametes produced in plants?
Male = Anthers Female = Ovules
Antigen presentation
Many cells, including macrophages place antigens of the pathogens they have encountered on the their cell surface membranes, where there is a good chance that a T or B-lymphocytes may encounter them stimulating an immune response.
What are Scrubbers?
Many factory chimneys contain alkaline materials such as Calcium Hydroxide, which absorbs the acidic gas such as NO2 and SO2, preventing it escaping.
Z-lines
Mark the ends of each sarcomere
Method of estimating population size of mobile organisms
Mark-release-recapture technique
What is the relative mass and charge on a neutron?
Mass 1 Charge 0
What is the relative mass and charge on a proton?
Mass 1 charge +1
What is the relative mass and charge on an electron?
Mass 1/2000 Charge -1
How do we calculate Enthalpy change?
Mass of solution x heat capacity (4.18) x temperature change
Systolic blood pressure
Maximum blood pressure in the arteries
Causes of mutation
May occur completely randomly but there are several environmental factors that increase chances of mutation: -ionizing radiation (alpha, beta and gamma) -ultraviolet radiation -mustard gas These cause damage to DNA molecules by altering the structure of the bases within them.
Species density
Measure of how many individuals there are per unit area.
Species frequency
Measure of the chance of a particular species being found within any one quadrat (record whether species was present in each quadrat analysed) E.g. quadrat placed 50 times and daisy plants found in 22 samples. Species frequency = 22/50 *100 = 44%
Species frequency
Measure of the chance of a particular species being found within any one quadrat. i.e. number of samples a species is recorded in (record whether species was present in each quadrat analysed) E.g. quadrat placed 50 times and daisy plants found in 22 samples.Species frequency = 22/50 *100 = 44%
Solubility of Mg(OH)2
Mg(OH)2 is insoluble in water Mg2+ + 2OH- → Mg(OH)2 (simplest ionic equation) Mg(OH)2 suspension in water, will be slightly alkaline, pH9 so some hydroxide ions have been produced by dissociation
Rate of disappearance of substrate example
Measure rate of disappearance of starch in breakdown of starch by amylase to form maltose. 1. Add amylase solution to starch suspension in a test tube. 2. Take samples of the reacting mixture at regular time intervals and test for the presence of starch using iodine in potassium iodide solution.
Rate of formation of product example
Measure rate of formation of oxygen in the decomposition of hydrogen peroxide by catalase. 1. All biological material contains catalase. Mash up potato tuber, mix with water and filter mixture to obtain catalase containing solution. 2. Add this to hydrogen peroxide in a test tube. 3. Measure rate of formation of oxygen by collecting gas in gas syringe and record volume every minute until reaction stops.
Explain how crossing over and random assortment of homologous chromosomes during meiosis and random fusion of gametes at fertilisation lead to genetic variation including the expression of rare, recessive alleles.
Meiosis creates genetic variation so making gametes genetically different. CROSSING OVER: • During prophase I, homologous chromosomes come together and pair up. • (crossing over occurs between non-sister chromatids) The non-sister chromatids twist around each other and bits of the chromatids swap over (they break off their chromatid and join onto the other chromatid) - EXCHANGE OF GENETIC MATERIAL • The chromatids still contain the same genes but now have a different combination of alleles. The crossing-over of chromatids during prophase I means that each of the four daughter cells formed from meiosis contain chromatids with different combinations of alleles. RANDOM ASSORTMENT: • Each of your cells contain 23 pairs of chromosomes. In each pair, one chromosome is maternal and one is paternal. • During metaphase I and II there are different ways in which the chromosomes can line up along the equator. This affects the type of chromosomes that finally go into each cell, so each cell ends up with a different combination of alleles So crossing over, plus the independent assortment of chromosomes and chromatids during meiosis, means that gametes end up with a unique assortment of alleles (i.e. all the cells are genetically different) RANDOM FUSION OF GAMETES: During fertilisation, any egg can fuse with any sperm, which also creates variation. Therefore new individuals have a new mixture of alleles, making them genetically unique.
Cells communicate with each other using....
Messenger molecules
What is metallic bonding?
Metal elements exist as giant metallic lattice structures. The outermost shell of electrons of a metal atom is delocalised, leaving a positive metal ion. The positive metal ions are attracted to the delocalised negative electrons.
Complex
Metal ion with ligands co-ordinately bonded to it.
Explain the Melting and Boiling points for Na, Mg and Al:
Metallic bonding is strong; and becomes stronger as there are more electrons in the outer shell, which are released into the sea of delocalised electrons. A smaller positive centre also makes the bonding stronger, meaning higher energy is needed to break the bonds.
What is Propogation two of Methane?
Methyl radical reacts with a chlorine molecule, creating another chlorine radical and Chloromethane. The free-radical number stays the same.
Explain the small drop between Mg and Al:
Mg has its outer electrons in the 3s subshell, whereas Al is starting to fill the 3p subshell. Al's electron is slightly easier to remove because the 3p electrons are higher in energy.
Why is Titanium expensive?
Mg is expensive. It is a batch process - making it expensive as the process is slower (filling/emptying reactors requires time) and more labour and energy is therefore required. The energy is lost when the reactor is cooled after stopping. The Ar atmosphere is expensive. The need to remove moisture due to TiCl4 being susceptible to hydrolysis. High temperatures are required in both steps.
How would you prepare Group 2 metals for reaction? What are the results?
Mg will burn in oxygen with a bright white flame, but can also burn slowly without a flame. Mg will often have a MgO layer, which needs to be cleaned with Emery paper before any reactions with Mg ribbon can occur. If testing for reaction rates with Mg and an acid, an uncleaned Mg ribbon would give a false positive result because both the Mg and MgO would react at different rates.
Organelles that produce ATP
Mitochondria Chloroplasts
Location of Krebs cycle
Mitochondrial matrix
Location of link reaction
Mitochondrial matrix
What are Fractions?
Mixtures of Hydrocarbons with similar boiling points, which are removed from the same level of the fractionating column.
Difference between diffusion and facilitated diffusion
Molecule passes through protein channel or carrier instead of passing between phospholipid molecules
Coenzyme
Molecule required for an enzyme to be able to catalyze a reaction
What is the arrangement of Molecular substances, such as Iodine?
Molecules are held in a regular arangement of I2 molecules, by weak intermolecular (van der Waals) forces.
Enantiomer
Molecules with a chiral carbon atom that exist as two non-superimposable mirror images
How do we calculate Moles - give 2 equations.
Moles = Mass/Ar or Mr Moles = Concentration x Volume
How do you calculate Moles, in terms of Avogadro's Law?
Moles = Number of Particles / Avogadro's Number (6.022 x 10^23)
How do we calculate Moles at Equilibrium?
Moles of reactant at equilibrium = initial moles - moles reacted Moles of product at equilibrium = Initial moles - moles formed
Hexose sugar
Monosaccharide with six carbon atoms in each molecule
Increasing Surface Area causes:
More frequent collisions so increased rate of reaction
What causes mutations?
Mutations occur randomly, but have environmental factors that significantly increase the chances of mutation: 1. All ionising radiation (alpha, beta, gamma) - damage DNA molecules, altering structures of the bases within them. 2. Ultraviolet radiation - similar effect
What causes variation?
Mutations which cause new forms of genes to be formed called alleles
Transmission of Tuberculosis
Mycobacterium tuberculosis enters the lungs through airborne droplets of liquids that are breathed in. 1. When infected person coughs or sneezes droplets containing the pathogen and inhaled by uninfected. 2. Infected by drinking unpasteurized milk as well. 3. Affects the lung tissue first as it is rich in O2. 4. But remians dormant until the immune system is weakened.
Myeloid leukaemia
Myeloid stem cells = cancerous Stem cells responsible for producing neutrophils divide uncontrollably and number of immature cells increases.
Coenzymes in respiration
NAD, FAD
Advantages of using Hydrogen for extraction
No pollution, readily available, better purity than C (no carbides are formed)
Differences between cyclic and non-cyclic photophosphorylation
Non-cyclic: Involves both photosystem I and II ATP, reduced NADP and O2 produced Cyclic: Involves only photosystem I Only ATP produced
Sickle cell anaemia description
Normal form of haemoglobin = HbA Sickle cell haemoglobin = HbS (causes sickle cell anaemia) Results in substitution mutation of the base T in place of A on the gene that codes for Beta-globin polypeptide in the haemoglobin molecule. One triplet is different so different amino acid used when forming polypeptide on ribosome. DNA base sequences Normal allele - codes for HbA : CAG = glutamic acid Abnormal allele - codes for HbS: CTG = Valine These amino acids are found on outside of haemoglobin molecules when it takes up tertiary and quaternary structures. -> Glutamic acid is hydrophilic = makes haemoglobin more soluble. -> Valine is hydrophobic = makes haemoglobin less soluble. When HbS is in areas of low oxygen concentration they stick to one another forming big chains of insoluble molecules -> forming long fibres. This pulls the red blood cells out of shape, making them sickle shaped instead of round. So no longer able to move easily through blood system and may get stuck in capillaries = painful/fatal
Co-Ordination Number
Number of co-ordinate bonds from ligands to metal ions
Glycolysis
Occurs in cytoplasm. One molecule of glucose split into two smaller molecules of pyruvate. First stage of both aerobic and anaerobic respiration.
Lactate fermentation
Occurs in mammals and produces lactate *Reduced NAD from glycolysis transfers hydrogen to pyruvate to form lactate and NAD. *NAD can be reused in glycolysis. Production of lactate regenerates NAD so glycolysis can continue even when there isn't much oxygen, so small amount of ATP can still be produced to keep biological processes going.
Krebs cycle features
Occurs in matrix Series of redox reactions Happens once for every pyruvate molecule, so goes round twice per glucose molecule.
Alcoholic fermentation
Occurs in yeast cells and produces ethanol 1. CO2 is removed from pyruvate to form ethanal. 2. Reduced NAD transfers hydrogen to ethanal to form ethanol and NAD. 3. NAD reused in glycolysis.
Optical Isomerism
Occurs where there are three bidentate ligands in an octahedral complex. They basically look like mirror images of each other.
Geometric Isomerism
Occurs where there are two ligands of one type different to the other ligands.
Why can oestrogen and progesterone pass through cell membranes but not FSH and LH?
Oestrogen and Progesterone are steroid based
F2
Offspring resulting from the cross between two F1 heterozygous organisms.
If you want to compare two reactions with/without a catalyst, why is it better to measure the initial rate of reaction?
Over time, the amount of product being formed decreases. Rate of reaction decreases. This is because the substrate is being used up to make products hence an increasingly lower conc of substrate so less frequent successful collisions
Gametogenesis in flowering plants (Female gametes)
Ovules 1. Large diploid spore mother cell develops in ovule. 2. This cell divides by meiosis to produce four haploid cells. 3. All but one of these degenerates, and the one surviving haploid cell develops into an embryo sac. 4. The embryo sac grows larger and its haploid nucleus divides by mitosis three times, forming eight haploid nucleus. One of these become the female gamete.
What is Ozone depletion by CFCs?
Ozone found mainly in the stratosphere (upper atmosphere) limits the access of UV radiation. Chlorine radicals are formed from Chlorofluorocarbon accumulation (Aerosols, Fridges, Solvents) and UV.
What is the Ideal Gas Equation?
PV = nRT Pressure in Pascals. Volume in metres. R = 8.31 Temperature in Kelvin (+273)
Uses of Poly(Chloroethene):
PVC is hard and brittle, so plasticisers such as phthalates (a small group of compounds). This makes the polymer softer, more flexible and less brittle. This means it can be used in industry, such as construction, automotive, textiles and for wires.
Codominant
Pair of alleles that both have an effect on the phenotype of a heterozygous organism
Bivalent
Pair of homologous chromosomes
Stages of glycolysis
Phosphorylation: *Glucose is phosphorylated by adding 2 phosphates from 2 ATP molecules. *Forming hexose bisphosphate and 2 ADP. *Hexose bisphosphate split into 2 molecules of triose phosphate. Oxidation: *Triose phosphate is oxidised (loses hydrogen) forming 2 pyruvate molecules. *NAD collects the hydrogen ions, forming 2 reduced NAD. *4 ATP produced. Net gain of 2 ATP.
Electron micrograph
Photograph taken with electron microscope
Photo/light micrograph
Photograph taken with light microscope
Why do plants need energy? x5
Photosynthesis Active transport DNA replication Cell division Protein synthesis
What do they photosynthetic pigment and protein make up?
Photosystem
Photosystems involved in non-cyclic photophosphorylation
Photosystem I and II
Photosystem involved in cyclic photophosphorylation
Photosystem I only
How are the photosynthetic pigments arranged?
Pigments arranged in light harvesting clusters called photosystems. In a photosystem, several hundred accessory pigment molecules surround a primary pigment molecule, and the energy of the light absorbed by the different pigments is passed to the primary pigments. Primary pigments = REACTION CENTRES
Muscles involved in raising and lowering of body hairs
Pili erector muscles
Colour of Co2+ metal aqua ion in soln
Pink
How is a frame quadrat used?
Placed on ground and number of individuals of each species is recorded in each quadrat. OR Percentage cover of a plant species can be measured by counting how many out of the 100 squares are covered by the species
Where is transmission of tuberculosis more likely to occur
Places where many people are living in crowded conditions
h
Planck's constant
Gibberellin
Plant hormone which controls seed germination in plants such as wheat and barley by stimulating the synthesis of amylase
C4 plants
Plant in which first product of photosynthesis is a four-carbon compound; most tropical grasses (but not rice)
C3 plants
Plant in which the first product of photosynthesis is a three-carbon compound
Xerophytes
Plants that are adapted to live in an environment where water is in a short supply. They are adapted to reduce water loss by transpiration.
Which cells produce antigens?
Plasma cells (derived from B-lymphocytes)
Use of poly(ethene)
Plastic Bags, buckets, bottles, its flexible, easily moulded, low density, water and chemical proof
Which Transition metals are used as Catalysts in a Catalytic converter.
Platinum, Rhodium or Palladium.
End point
Point at which the indicator changes colour
Equivalence point
Point in a titration where sufficient base has been added to just neutralise the acid (or vice versa)
Saturation point
Point where a factor is no longer limiting the reaction - something else has become the limiting factor
Water-soluble molecules
Polar molecules
Alkali
Produces hydroxide ions in aqueous solution
Chromosomes in prokaryotes
Prokaryotes carry DNA as chromosomes, which is supercoiled to fit in cell
What causes the difference in the mean energy values of the respiratory substrates
Proportional to amount of hydrogen atoms. More hydrogen atoms available to reduce coenzymes = more energy generated in ETC
Effect on protein if even one wrong amino acid is added to sequence
Protein becomes non-funcitoning
Histone
Protein molecule around which DNA is tightly coiled around to form chromatin
Bronsted Lowry acid
Proton donor
Benefit of branching in amylopectin and glycogen
Provides a greater surface area for the enzyme reaction allowing glucose to be released more quickly.
How does a Catalyst work?
Provides an alternative route with a lower Ea, so more particles have E>Ea, so the fraction of successful collisions increases
Function of collenchyma in leaf
Provides strengthening
Name of covalent bond between phosphate groups in ATP
Pyrophosphate bonds
Major products of gylcolysis
Pyruvate ATP Reduced NAD
Mark-release recapture
Quadrats not suitable for finding or counting mobile animals. Good method of estimating population size of mobile organisms - mark-release-recapture technique. 1. As many individuals as possible are caught. 2. Each individual is marked in a way that won't affect future chance of survival. 3. The marked individuals are counted, returned to their habitat and left to mix randomly with rest of the population. 4. When enough time has elapsed for the mixing to take place, another large sample is captured. 5. Number of marked and unmarked individuals counted. 6. Proportion of marked to unmarked individuals is then used to calculate an estimate of the total number in the population. Example: if one-tenth of second sample was marked, then you presume that you originally caught one-tenth of the population in first sample. So estimation is that number in population is ten times the number caught and marked in first sample.
What RQ value indicates anaerobic respiration is occuring on top of aerobic respiration?
RQ value above 1
Hydrolysis reaction
Reaction in which a complex molecule is broken down into simpler ones, involving the addition of water
Condensation reaction
Reaction involving the joining of two molecules by removal of a water molecule
Explain collision Theory
Reactions only take place between particles that collide with sufficient energy energy is used to break the bonds in one or either of the reactant molecules
Lymphocytes
Recognise specific pathogens through interaction with receptors in their cell surface membranes, and respond in one of several ways, for example by secreting antibodies. 1. B-lymphocytes: - Plasma cells - Memory cells 2. T-lymphocytes: - T killer cells - T helper cells - Memory cells 3. Natural killer cells
What flame colour is Calcium?
Red
Erythrocytes
Red blood cells
Species diversity
Refers to all the species in an ecosystem. Takes into account the number of species (species richness) and also includes a measure of the evenness of the abundance the different species. Greater species diversity = greater number of species + the more evenly the number of organisms is distributed amongst the different species.
Resolution limit
Refers to that any object can be resolved if it is larger than half the wavelength of the rays (light/electron beam) being used
In the body why are new action potentials only generated ahead and not behind?
Region behind still recovering from action potential it just had, and sodium ion voltage-gated channels are shut tight and cannot be stimulated to open, however great the stimulus.
Temperature
Related to average Kinetic Energy of particles in a system, particles move faster and Kinetic Energy increases so temperature goes up. Temperature is independent of amount of substance.
What is relative isotopic mass?
Relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of Carbon-12 is exactly 12.
Decarboxylation
Removal of carbon dioxide from a molecule
Structure of kidney (check pg 305 text book)
Renal artery/vein: Kidney receives blood from RENAL ARTERY and returns blood through RENAL VEIN. Ureter: Narrow tube carrying urine from kidney to bladder. Urethra: Carries urine from bladder to out of body. Capsule Cortex Medulla Pelvis: Where ureter joins with kidney Kidney made up of many nephrons (tube structures) and blood vessels
Menstrual cycle description
Repeating process of change in ovaries, oviducts and uterus, which takes place approximately every 28 days from puberty to menopause. Controlled by: -Steroid hormones secreted by ovaries: i. Oestrogen ii. Proesterone -Gonadotropic peptide hormones secreted by anterior pituitary gland: i. FSH (follicle stimulating hormone) ii. LH (luteinising hormone)
Telomeres
Repetitive sequences of DNA at the end of chromosomes that protect genes from chromosome shortening that happens at each cell division.
What type of protein is produced by regulatory genes?
Repressor proteins
Cells release energy from glucose by....
Respiration
When are the voltage gated potassium/sodium channels closed or open?
Resting potential: Bot closed Depolarisation: K - closed, Na - open Polarisation: K - open, Na - closed
Sickle cell trait
Result of being heterozygous between normal haemoglobin and sickle cell haemoglobin The two alleles are codominant .
Active natural immunity
Result of person previously having had the disease and forming B or T memory cells. - So next time, body rapidly manufactures antibodies.
What is used to make nucleic acids (using products of calvin cycle)
Ribose sugar in RNA made using TP
Sizes of cells structures in ascending order
Ribosomes Centrioles Lysosomes Mitochondria Nucleolus Nucleus
When do blood glucose concentration rise and fall?
Rises after eating food containing carbohydrate Falls after exercise, as more glucose is used in respiration to release energy
What are Ores?
Rocks that contain enough of a metal that is economically viable to quarry and extract.
Ore
Rocks with a high enough percentage of a metal to be extracted commercially
Problem of photo respiration
RuBP wasted, so less available to combine with CO2
How many electrons does each subshell hold?
S - holds up to 2 electrons. P - holds up to 6 electrons. D - holds up to 10 electrons.
Similarities and differences between artificial selection and natural selection?
SIMILARITIES: -Both change the allele frequencies in the next generation - alleles coding for desirable characteristics become more common in next generation. -Both may make use of random mutations when they occur - if a random mutation produces an allele that vies beneficial characteristic it's selected for in next generation. DIFFERENCES: -Organisms that reproduced are selected for by humans in artificial selection and the environment in natural selection. -Artificial selection aims for predetermined result whilst natural selection result is unpredictable. -Natural selection makes species more adapted to environment, artificial selection makes species more useful for humans.
Example of source and sink
SUCROSE Source: leaves Sink: other parts of the plant
Describe apparatus and method used to investigate how temperature affects photosynthesis in pond weed
Sample of pond weed placed in test tube of water. Test tube would be placed in a beaker containing water at a known temperature. The test tube would be connected to a capillary tube of water and the capillary tube connected to a syringe. The pond weed would be allowed to photosynthesize for a set period of time. Afterwards, the syringe would be used to draw the bubble of oxygen produced up the capillary tube where its length would be measured using a ruler. The experiment is repeated and the mean length of gas bubble is calculated. then the whole experiment is repeated at several different temperatures.
What are the chemical properties of addition polymers?
Saturated. Generally unreactive (although they can combust to release toxic gases). Held together by weak van der Waals forces, meaning layers can slide over eachother.
Advantages of Recycling Metals
Saves Resources, Less waste, less landfill, less air pollution, saves energy,
What difference is found between the original Bohr atom model and the refined Bohr model?
Scientists discovered that not all electrons in a shell have the same energy, so it was refined to include sub shell's.
Bonds in secondary structure
Secondary structure is held together by hydrogen bonds forming between electronegative oxygen atoms on CO groups and electropositive hydrogen atoms on NH groups
Primary structure
Sequence of amino acids in poly peptide chain
Metabolic pathway
Series of small reactions controlled by enzymes e.g. respiration
Haemophilia descripition
Sex-linked disease Sex linked gene codes for factor VIII protein - needed for blood clotting. Two alleles for this gene: -Dominant allele H = produces normal factor VIII protein -Recessive allele h = results in lack of factor VIII protein -> causing haemophilia where blood fails to clot properly. Gene only found on X chromosome: Women have 2 copies of gene and males have only 1
What happens if tertiary structure of an enzyme is altered
Shape of active site is changed
What are sharp and broad peak?
Sharp peaks are peaks which occur at very precise frequencies. Broad peaks occur over a range of frequencies.
Increasing temperature
Shifts the equilibrium in the endothermic direction
Explain the Melting and Boiling point for Si:
Si is Macromolecular, meaning there are many strong covalent bonds between atoms resulting in high energy being needed and therefore it has a high melting and boiling point.
Example of recessive genetic disorder
Sickle cell anaemia
What does sickle cell haemoglobin (HbS) cause
Sickle cell anaemia
Cells in phloem tissue
Sieve tube elements
What are the Reagents used for testing Halides?
Silver Nitrate and Nitric Acid.
What is the melting point of a covalent bond?
Simple covalent bonds have low melting points because the weak forces between molecules are easily broken.
What is the electrical conductivity like in a covalent bond?
Simple covalent compounds don't conduct electricity because there are no free ions to carry the charge.
Thymus
Site where imamture T-cells mature
Weak Acid
Slightly Dissociate
Weak Base
Slightly Dissociate
Disadvantages of fermentation of Glucose to produce ethanol
Slow batch process, stopping and starting high production costs ethanol needs to be purified using fractional distillation depletes land used for growing food crops
Rate determining step
Slowest step in the overall equation that governs the rate of the chemical reaction
Benefit of capillaries being so narrow that blood cells have to squeeze through
Slows blood flow and minimises the distance of the diffusion pathway.
Viruses
Small infectious agents that can only replicate inside other living cells
Plasmids
Small loops of DNA found in bacteria, that contain genes for antibiotic resistance. Can be passed between bacteria.
Features of hormones
Small proteins - water soluble So can't cross the phospholipid bilayer of cell surface membranes
Nodes of Ranvier
Small, uncovered areas of axon between Schwann cells
How do arterioles control the blood flow to different parts of the body
Smooth muscles in their walls contract and relax to control the blood flow. Contraction = restriction of blood flow Relax = full blood flow
Why does DNA replication occur before mitosis
So that each new daughter cell has a full set of DNA
Why is it important for the coiling of DNA before cell division
So the chromatids do not tangle up during cell division, allowing easy separation of chromatids.
Why might a neurone have lots of mitochondria?
Sodium-potassium pump works by active transport.
What happens if plants get too much water
Soil becomes waterlogged reducing the uptake of magnesium for chlorophyll a
Quaternary structure
Some proteins are made of several different polypeptide chains held together by bonds. (Quaternary structure is the way in which these polypeptide chains are assembled together)
Oxidising agent
Something that accepts electrons and gets reduced.
What are the steps in calculating relative atomic mass?
Step 1: For each peak multiply the relative isotopic abundance by the relative isotopic mass. Step 2: Add up these totals. Step 3: Divide by 100
Where does the light independent reaction take place?
Stroma
What makes cellulose strong
Strong fibres = MICROFIBRILS
Microfibrils
Strong fibres formed as a result of hydrogen bonds forming between different cellulose chains leading to the chains associating into bundles.
Irreversible inhibition
Strong, covalent bonds are formed between the inhibitor and the enzyme so they can't be easily removed
In which veins is the lymph returned to the blood
Subclavian veins
Antigen
Substance that is foreign to the body and stimulates an immune response.
Pigment
Substance which absorbs light of a particular wavelength, but not others. Wavelengths of light not absorbed are reflected.
Enzyme inhibitors
Substances that decrease the activity of enzymes
Mutagen
Substances that increase the chances of mutation occurring
Polynucleotides
Substances whose molecules are made of long chains of nucleotides linked together. (Nucleotides join to form polynucleotide strands)
Chelate Effect
Substitution of a unidentate ligand by a multidentate ligand giving a more stable complex and an increase in entropy
What is the reaction of Chlorination?
Substitution.
What are the main substances moved by phloem tissue
Sucrose and amino acid which are in solution in water.
Advantages of fermentation of Glucose to produce ethanol
Sugar is renewable, low technology level = cheap equipment
How are Sulphur impurities dangerous?
Sulphur impurities react with oxygen to produce Sulphur dioxide; which may be oxidised to Sulphur trioxide. Both gases dissolve in rainwater forming acid rain, which causes the erosion of buildings and statues, kills plants and trees and kills fish through the contamination of lakes.
Explain the small drop between Phosphorus and Sulphur:
Sulphur's outer electron is being paired up with another electron in the same 3p orbital. When the second electron is added to an orbital, there is a slight repulsion between the two negatively charged electrons which makes the second electron easier to remove.
Pathways of movement of water through the root into the xylem
Symplast pathway Apoplast pathway
What are neuromuscular junctions?
Synapses between neurones and muscles
Role of magnesium ions in plants
Synthesis of chlorophyll
Function of ribosomes
Synthesis of rRNA
Endoplasmic reticulum
System of membranes enclosing fluid-filled space (cisternae)
Cells that mature away from the bone marrow
T-cells Monocytes
Global pattern of TB
TB is found in all countries of the world including developed countries such as the USA and the UK. -However it is most common in areas where living conditions are poor and crowded, or where large numbres of people have HIV/AIDS.
Why is it important to maintain the blood glucose concentration?
TOO HIGH = water potential o blood reduced to point where water molecules diffuse out of cells into blood by osmosis - causing cells to shrivel up and die. TOO LOW = cells unable to carry out normal activities because there isn't enough glucose for respiration to provide energy.
Thermoregulation mechanisms when temperature is too high/low
TOO LOW 1. Vasoconstriction 2. Lower sweat secretion 3. Body hairs raised 4. Adrenaline secreted 5. Shivering TOO HIGH 1. Vasodilation 2. Increased sweat secretion 3. Body hairs lowered 4. No adrenaline secreted 5. No shivering
Link reaction
Takes place in mitochondrial matrix. 1) Pyruvate is decarboxylated - one carbon atom removed from pyruvate in form of CO2. 2) NAD reduced - collects hydrogen from pyruvate, changing pyruvate into acetate. 3) Acetate combined with coenzyme A to form acetyl coenzyme A. 4) NO ATP PRODUCED
What is Avogadro's Law?
That equal volumes of different gases at a Constant pressure and temperature will contain equal numbers of particles.
Explain the increasing stability from Primary carbocations to Tertiary carbocations:
The Alkyl group in the Tertiary carbocations contains a greater electron density than hydrogen atoms. This density is attracted towards and reduces the positive charge on the carbon atom, which has a stabilising effect.
What is the trend of the Atomic Radius across a period?
The Atomic Radii decrease as you move across a period from left to right, as more protons are being added, the effective nuclear charge increases, creating a more positive charge attraction for the electrons in the same shell with similar shielding.
What is the trend of the Atomic Radius down Group 2?
The Atomic radius increases down the group, as the atoms have more shells of electrons making them bigger within the same effective nuclear charge.
Which bonds are more likely to break?
The C-C bonds are weaker than the C-H bonds, so break more easily when heated.
Why are Halogenoalkanes likely to be attacked by Nucleophiles?
The C-X bond is polar, as all Halogens are more electronegative than Carbon.
Bond Dissociation Enthalpy
The Enthalpy Change needed to break 1 mole of a covalent bond with all species in the gaseous state The energy given out is the same as the amount taken in when the bond is formed always endothermic, ∆H is positive ∆H = ∑(Bonds Broken) - ∑(Bonds Formed)
Mean Bond Enthalpy
The Enthalpy Change needed to break a bond, averaged over different molecules
Standard Molar Enthalpy of Combustion
The Enthalpy Change when 1 mole of a substance is completely burned in excess oxygen under standard conditions with all reactants and products in their standard states. ∆Hc = ∑∆Hc(Reactants) - ∑∆Hc(Products)
Standard Molar Enthalpy of Formation
The Enthalpy Change when 1 mole of a substance is formed from it's constituent elements under standard conditions. With all reactants and products in their standard states ∆Hc = ∑∆Hf(Products) - ∑∆Hf(Reactants)
Why is Hydrochloric acid needed when testing for ions, such as Barium Sulphate?
The Hydrochloric acid is needed to react with the Carbonate impurities that are often found in salts, which would form a white Barium Carbonate precipitate and give a false result. Sulphuric acid cannot be used as it contains Sulphate ions, and would give a false positive result.
What is Initiation?
The UV light is absorbed by chlorine molecules, providing energy to break the bond. One electron goes to each chlorine, creating two free radicals during Homolytic Fission.
What is electronegativity?
The ability to attract the bonding electrons in a covalent bond. It is meausred on the Pauling scale. The higher the number the better the ability to attract the bonding electrons.
What is Catenation?
The ability to form bonds between atoms of the same element. For example, Carbon catenates to form chains and rings with single, double or triple bonds.
Resolution
The ability/ how well a microscope distinguishes between two objects very close together. (The greater the resolution, the greater the detail that can be seen.
Primary response
The activation of the immune system by an antigen that has entered the body for the first time.
Secondary response
The activation of the immune system by an antigen that has previously been exposed to the body, therefore producing a quicker immune response.
Induced fit theory
The active site is flexible. It only assumes it's catalytic conformation after the substrate molecules bind to the site. When the product leaves, the active site reverts back to its inactive shape.
Molecular Formula
The actual number of atoms of each element in a molecule
Nicotine
The addictive drug found in cigarettes (tobacco). - Affects nervous system by binding to the receptors on the neurones in the brain and other parts of the body. - It increases the release of the neurotransmitter dopamine in the brain, giving feelings of pleasure.
Oxygen debt
The additional oxygen involved in conversion of lactate to glucose.
What does the percentage saturation of haemoglobin with oxygen represent on a dissociation curve
The affinity of haemoglobin for oxygen. 1. Shifted to right =low affinity =O2 released (so for active animals) 2. Shifted to left =high affinity =Hb combines with O2 more readily
Genotype
The allele's possessed by an organism
Energy gap ΔE
The amount of energy needed for an electron to transfer to a higher orbital.
What is an Enthalpy Change?
The amount of heat energy taken in or given out during any change in a system, provided the pressure is constant.
What is the Relative Molecular Mass?
The average mass of a molecule compared to 1/12th the mass of a Carbon-12 atom.
What is relative atomic mass?
The average mass of an atom of an element compared to one twelfth of the mass of an atom of carbon 12.
What is the Relative Atomic Mass?
The average mass of an element compared to 1/12th the mass of a Carbon-12 atom.
What is relative molecular mass?
The average mass of an entity compared to one twelfth of the mass of an atom of carbon 12.
What determines the amino acid that can be loaded onto the tRNA molecule
The base sequence of the anticodon
Metabolism
The biochemical modification of chemical compounds in living organisms and cells. Includes anabolism (synthesis of organic molecules) and catabolism (breakdown).
Why is the blood pressure in veins less than in arteries
The blood is further away from the pumping effect of the heart in the veins than in the arteries.
Why is the blood system called a closed system
The blood travels inside the blood vessels
What are Mechanisms?
The breaking down of a reaction into a series of smaller steps, using curly arrows to represent the movement of electrons and the breaking/formation of bonds.
What is fragmentation?
The breaking of a molecular ion into two smaller, more stable species (a charged ion and a free radical).
Lysis
The bursting of a cell due to movement of water into the cell by osmosis after exposure to a hypotonic solution.
Autocatalyst / Autocatalysed
The catalyst is a reaction product
Effect of mutation in a gene that controls cell division
The cells grow out of control and divide uncontrollably to form a tumour.
Why is 'resting stage' not an appropriate description for cells in interphase
The cells still carry out many functions such as: -protein synthesis -DNA replication -organelle replication -respiration
What is the Rate of Reaction?
The change in concentration of a substance in unit time, usually in mol dm-3s-1.
Rate of Reaction
The change in concentration of either reactants or products per unit time
What does voltage gated mean?
The channels open or close at certain potential difference values.
What is a Dipole?
The charge difference due to electronegativity differences.
What is Photochemical Smog?
The chemical reaction of sunlight, Nitrogen oxides, and volatile organic compounds in the atmosphere, leaving airborne particles and ground-level Ozone. It is present in cities with a lot of vehicles, where it is sunny, warm and dry.
Zygote formation
The chromosomes of the spermatozoan and the ovum join together to form a single diploid nucleus, and the cell that is made by this process is called a zygote. The zygote can now divide repeatedly by mitosis to form first an embryo, then a fetus.
What determines the direction of phloem transport
The concentration gradient of the solutes
What is Fractional Distillation?
The continual evaporation and condensation of a mixture forming gases at different boiling points, where fractions (with similar boiling points) are removed at the same level.
What happens to the blood when the walls of a chamber in the heart contracts
The contraction causes the walls of the chamber to squeeze inwards on the blood
How does fractional distillation work?
The crude oil is vaporised at about 350 degrees Celsius and it rises up through the trays. The largest hydrocarbons don't vapourise at all, because their boiling points are too high. As the crude oil vapour goes up the fractional column, it gets cooler creating a temperature gradient. As the alkanes get bigger their boiling point increases so each fraction condenses at a different temperature. The hydrocarbons with the lowest boiling points don't condense, they're drawn off as gases at the top of the column.
How does metallic bonding explain metals ability to conduct electricity?
The delocalised electrons can pass kinetic energy to each other, making them good thermal conductors. Metals are good electrical conductors because the delocalised electrons can carry a current.
Variation
The differences that exist between individuals. It occurs between or within species.
What are Formulae?
The different ways of representing the atoms present in a compound or molecule.
Facilitated diffusion
The diffusion of ions and polar molecules through cell membranes using specific protein channels or carriers, down a concentration gradient.
Osmosis
The diffusion of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane.
What is the Atomic Radius?
The distance from the Nucleus to the outermost occupied electron energy level.
Why does E/Z (geometrical) isomerism occur?
The double bonds in Alkenes are unable to rotate.
What makes DNA stable
The double-helix structure with hydrogen bonds formed between the two strands
What is the Standard Enthalpy Change of Combustion?
The enthalpy change that occurs when 1 mole of a substance is combusted completely in excess oxygen under standard conditions (298k and 100kPa), with all reactants and products being in their standard states.
Enthalpy of Combustion
The enthalpy change when 1 mol of a compound Is completely burned in oxygen Under standard conditions, all substances in standard states
What is the Standard Enthalpy Change of Formation?
The enthalpy change when 1 mole of the compound is formed from its elements under standard conditions (298k and 100kPa), with all reactants and products being in their standard states.
What is a synapse
The junction between a neurone and another neurone, or between a neurone and an effector cell e.g. muscle or gland cell.
What is the Standard Enthalpy of Reaction?
The enthalpy change when substances react under standard conditions (298k and 100kPa) in quantities given by the equation for the reaction. Q=mc/\T
Multplie alleles
The existence of three or more alleles of a gene E.g. in the determination of A,B,O blood groups Gene that determines the antigen on red blood cells, and therefore your blood group has three alleles - Io, IA, IB IA and IB = codominant IO = recessive
What happens during the deflection stage of mass spectrometry?
The fast moving ions pas into a string magnetic field, deflecting the ions into a curved path. The degree of deflection depends on the Mass/charge ratio (m/z). Ions with with a high m/z ratio are deflected the least (they're heavier). The strength of the magnet is gradually increased so that ions with different m/z ratios are deflected towards the detector.
What is the first ionisation energy?
The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
What is reduction?
The gain of electrons. The loss of Oxygen. The gain of Hydrogen. Decrease in oxidation state.
What is the trend of the First Ionisation Energy across a period?
The general trend is to increase, due to increasing numbers of protons as the electrons are being added to the same shell.
Cardiac muscle is myogenic
The heart muscle can contract and relax automatically without the stimulation from nerves
How is blood kept moving in the blood vessels by mass flow
The heart pumps the blood by producing a high pressure
What is the Second Ionisation Energy?
The heat energy required to remove 1 mole of electrons from each free gaseous unipositive ion of an element.
Describe the layout of an Infra-red spectrum:
The horizontal axis is the wave number ( ), which is closely related to frequency. The vertical axis shows the transmittance, expressed as a percentage. A transmittance below 50% shows that a significant quantity of the radiation has been absorbed at a specific frequency. This is a peak.
What happens when enough mRNA has been produced
The hydrogen bonds between the uncoiled strands of DNA re-form, and the strands coil back into a double helix.
What is a Carbocation?
The intermediates which are produced during electrophilic addition; which are carbon atoms with a positive charge. They can be attracted by anything with a negative charge or lone pair of electrons.
Osmosis
The net movement of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential/(down a water potential gradient).
What is an Effective Nuclear charge?
The net positive charge experienced by an electron with consideration of the electron shell shielding, which reduces the charge.
Co-ordination number
The number of co-ordinate bonds formed to a central metal ion
How does metallic bonding explain the melting points of metals?
The number of delocalised electrons per atom affects the melting point. The more there are, the stronger the bonding will be and the higher the melting point. The size of the metal ion and the lattice structure also affect the melting point.
What is a Coordination number?
The number of ions immediately surrounding a central atom in a complex or crystal. It is usually 4, 6 (such as NaCl) or 8.
What is the Atomic number?
The number of protons in the nucleus.
Species richness
The number of species in a community
Phenotype
The observable characteristics of an organism Characteristics of an organism often resulting from an interaction between its gentype and its environment
F1
The offspring resulting from a cross between an organism with a homozygous dominant genotype, and one with a homozygous recessive genotype.
Why are flame colours different?
The outer electrons are in a higher energy level so electrons are excited differently, releasing different light.
Respiration
The oxidation of respiratory substrate i.e. Glucose
What happens during the acceleration stage of mass spectrometry?
The positive ions are attracted by negatively charged plates in an electric field which accelerates the ions and focuses the beam.
What happens during the detection stage of mass spectrometry?
The positive ions hit an electrically charged plate/ the current produced is then amplified and recorded as a 'peak'. Each peak is a measure of the relative abundance of each ion.
How do the photosynthetic pigments allow maximum absorption of light energy?
The primary pigments absorb wavelengths of light corresponding to blue and red colors. Accessory pigments absorb wavelengths of light corresponding to blue, violet and green and transfer this energy to the primary pigments.
How does the primary structure affect its properties and functions (example)
The primary structure of an enzyme determines the tertiary structure, so affects the shape of the active site, so determines the substrate that binds to it.
Differentiation
The process by which stem cells become specialised cells.
Cell cycle
The process that all body cells from multicellular organisms use to grow and divide
What is Cracking?
The process that splits long chained alkanes into shorter chain alkanes, alkenes or hydrogen.
What problem occurs during Nucleophilic substitution by Ammonia? How is it prevented?
The product formed is a primary Amine, which has a lone pair so acts as a Nucleophile. The reaction is carried out with a large excess of Ammonia.
Respiratory rate
The rate at which an organism converts glucose to carbon dioxide and water (Measured by finding organism's oxygen consumption)
What are the expected results of testing the Relative rate of reaction of the Halogens?
The rate of reaction is determined by Bond strength (enthalpy) rather than bond polarity. C-F is the most polar and has the strongest bonding, so is the slowest to break.
What is the Relative Isotopic Mass?
The ratio of the mass of one atom and that isotope to 1/12th of the mass of a Carbon-12 atom.
What is the reactivity trend of group 2 metals down the group?
The reactivity increases down the group.
How can glycolysis occur in anaerobic respiration in the absence of oxygen?
The reduced NAD is oxidized to NAD is produced in the process after glycolysis which can be reused in glycolysis again
What is the trend of reducing power of the Halide ions?
The reducing power increases down Group 7.
What makes sure that action potentials only travel in one direction?
The refractory period Depolarisation only happens ahead of site of action potential, as preceding parts of neurone have just undergone action potential and ion channels are recovering and can't be opened.
What is the fingerprint region?
The region between 500 and 1500 , where peaks represent the structure of the molecule as a whole, not specific bonds. Every molecule can be identified by looking at this region as it is even different for those with the same functional group.
Centromere
The region of the chromosome that holds the two sister chromatids together during mitosis.
What is Electronegativity?
The relative tendency of an atom to attract the shared pair of electrons (electron density) in a covalent bond.
Bohr effect
The release of O2 when the pH is low, despite the high partial pressure of O2.
Why is there a low partial pressure of oxygen at respiring cells
The respiring cells use up the oxygen for respiration
Secondary structure definition
The structure of a protein molecule resulting from the regular coiling or folding of the chain of amino acids due to the formation of hydrogen bonds between different parts of the poly-peptide chain, e.g. an alpha-helix or beta-pleated sheet.
Induced fit theory specificity
The substrate doesn't only have to be the right shape to fit the active site, it has to make the active site change shape in the right way as well - thus explaining why enzymes are so specific
Overall order of reaction
The sum of the powers to which the concentration terms are raised in the rate equation
What happens to the regenerated coenzymes from oxidative phosphorylation?
They are reused in the Krebs cycle
Niche definition
The role of an organism in an ecosystem. (Organism's niche describes where it is, how it obtains energy, how it interacts with both its physical environment and with other species)
Niche
The role of an organism in an ecosystem. (Organism's niche describes where it is, how it obtains energy, how it interacts with both its physical environment and with other species.)
Why is a rubber tube used for Catalytic cracking?
The rubber tube prevents suck-back; where the gas will displace the water in the tube.
How do you obtain a clean Insoluble salt?
The salt is removed by filtration, washed with distilled water to remove any soluble impurities and then dried on filter paper.
What happens during the vaporisation stage of mass spectrometry?
The sample is turned into a gas using an electrical heater in a vacuum.
What is the second ionisation energy?
The second ionisation energy is the energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions.
The sequence of bases in a DNA molecule is a code that determines...
The sequence in which amino acids are linked together when making a protein molecule
How does the primary structure determine the 3D structure of a protein
The sequence of amino acid determines the type of bonds that will be formed, therefore determines how the protein will be folded into its final 3D structure.
How does a protein's primary structure determine its overall 3D structure
The sequence of amino acids determines the types of bonds formed, so determines how the protein will fold up into its 3D structure
Primary structure definition
The sequence of amino acids making up a polypeptide chain.
Amino acid sequence in variable regions of antibodies
The sequence of amino acids varies greatly between different antibodies
Effect of surface area - volume ration on diffusion rate
The smaller the cell is, the greater the surface area to diffusion rate, so the more quickly and easily materials can be exchanged between the cytoplasm and environment by diffusion.
Hydrolysis
The splitting of a molecule using water
Taxonomic system used for classifying viruses
The taxonomic system for classifying viruses is based on: • The diseases they cause • The type of nucleic acid they contain (DNA or RNA) • Whether the nucleic acid is single stranded or double stranded In cellular organisms, DNA is double stranded and RNA is single stranded, but in viruses both can be either.
How is the combustion of Nitrogen a problem?
The temperature in an internal combustion engine can reach over 2000'C, which causes some of the Nitrogen in the air to react with oxygen, forming Nitrogen monoxide and Nitrogen dioxide. Both gases destroy the Ozone layer. Nitrogen dioxide dissolves in rainwater to form acid rain. Oxides of Nitrogen are partially responsible for Photochemical Smog.
Describe the temperature gradient in a Fractionating Column:
The temperature is cooler at the top and hotter at the bottom, which means that when it reaches a section that is cool enough, it condenses in the bubble caps and is removed.
Function of tendinous cords in the heart
The tendinous cords attach the atrioventricular valves to the ventricles, preventing them from being forced up into the atria when the ventricles contract.
Heat
The total energy of all particles present in a given substance. Heat is dependent on the amount of substance
What is Hess' law?
The total enthalpy change for a reaction is independent of the route by which the chemical change takes place and dependant only on the initial and final states.
Oxidation state
The total number of electrons an element has donated or accepted.
What is the mass number?
The total number of protons and neutrons in the nucleus of an atom
What is the Mass number?
The total number of protons and neutrons in the nucleus of an atom.
Bacterial conjugation
The transfer of plasmids between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
How do the hydrophobic hydrocarbon tails of triglycerides make them insoluble
The triglycerides bundle together as insoluble droplets in cells: Hydrophobic fatty acid tails face inwards, shielding themselves from water with their glycerol heads.
Why might mutations not always cause a change in the amino acid sequence
The triplet code is degenerate so each amino acid is coded for by more than one triplet
What is the difference between amino acids determined by
The variable R group
Biodiversity
The variety of ecosystems and species in an area and the genetic diversity within species OR The degree of variation of life forms in an ecosystem. Includes diversity at three levels: - The variation in ecosystems or habitats - The number of different species in the ecosystem and their relative abundance - The genetic variation within each species
Biodiversity definition
The variety of ecosystems and species within an area and the genetic diversity within a species
What feature of xylem vessel elements helps with adhesion?
The vessel elements form a narrow tube.
Triglycerides are hydrophobic
They are insoluble and don't form hydrogen bonds with water
Why are plastics a problem?
They are not biodegradable, meaning they cannot be broken down and can remain in landfills. Although they can be recycled, it can only be done a limited number of times due to the polymer structure degrading each time it is heated.
How can Petrochemicals be obtained?
They are obtained either directly through Cracking (Pyrolysis) or from chemical processing of petroleum oil or natural gas.
Cell potential
The voltage between two half cells in a electrochemical cell.
Standard electrode potential
The voltage measured under standard conditions when a half cell is connected to a standard hydrogen electrode.
Cardiac output
The volume of blood pumped by the heart per minute(4-6 litres) CARDIAC OUTPUT=stroke volume x heart rate
Stroke volume
The volume of blood pumped out of left ventricle during each heart beat (75ml)
What is a titre?
The volume of solution added from the burette. On rough and two accurate titrations are carried out, and the average titre is the average of the two accurate (concordant - within 0.1) titres.
Why do electron microscopes have a greater resolutions than light microscopes?
The wavelength of a beam of electrons is smaller than light
Mass flow hypothesis
Theory that supports phloem transport/translocation
Why is the blood system called a double circulatory system
There a two circuits/systems: 1. Pulmonary system = blood travels from the heart to the lungs, and back to the heart. 2. Systemic system = blood travels from the heart to the rest of the body, and back to the heart.
Why is the CN chain extension useful in organic synthesis?
There is not many simple methods to forming C-C bonds. The CN can be changed to other groups.
Examples of Endothermic Reactions
Thermal Decomposition e.g. CaCO3 → CaO + CO2
What is thermal cracking?
Thermal cracking takes place at a high temperature of up to 1000'C and high pressures of up to 70 atm. It produces a lot of alkenes which are used to make valuable products like polymers.
What are unburnt hydrocarbons.
These are emitted when engines don't burn all of the fuel molecules. These hydrocarbons react with nitrogen oxides in the presence of sunlight to form ground level ozone (O3) which is a major component of smog
What are dipole-dipole forces?
These occur between polar molecules. A dipole-dipole force is the attraction between the positivity on one molecule and the negativity on another.
Why does chlorophyll a and chlorophyll b appear green?
They absorb red and blue light in sunlight so green light is reflected.
Why are fossil fuels a problem for the environment?
They are burned faster than they are formed, leading to a net increase in the amount of atmospheric Carbon dioxide; which is responsible for climate change.
What are TP and GP used for?
They are converted into useful organic substances 1. CARBOHYDRATES: hexose sugars (e.g. glucose) made by joining two TP molecules. Larger carbohydrates made by joining hexose sugars. 2. LIPIDS: Glycerol - triose phosphate Fatty acids - glycerate 3-phosphate 3. PROTEINS: Some amino acids - glycerate 3-phosphate 4. NUCLEIC ACIDS: Sugar in RNA (ribose) - triose phosphate
What is an Induced dipole-dipole force?
They occur between all atoms and molecules. The more electrons present in a molecule, the greater the van der Waals forces of attraction between the molecules - explaining the increase in boiling point down group 7.
How do conezymes work
They transfer a chemical group from one molecule to another. - Oxidises a molecule (takes hydrogen from) - Reduces a molecule (gives hydrogen to)
Myelin sheath definition
Thick insulating layer around axon that has high electrical resistance.
Function of surfactant
Thin layer of fluid that covers the alveoli. Reduces surface tension of the fluid layer lining the alveoli, preventing the alveoli from collapsing during exhalation.
Why are gametes produced using meiosis?
This helps create genetic variation.
What is the Atomic (proton) number?
This is the number of protons in the nucleus of an atom and is used to identify an element
Benefity of hydrogen ions displacing oxygen in oxyhaemoglobin
This process helps to control the pH in the body, by preventing the H+ ions from increasing the cell's acidity.
Why is meiosis used for gamete production?
This results in gametes containing only one set of chromosomes, rather that two sets. If number of chromosomes weren't halved, the number of chromosomes would double every generation.
describe Thomson's model of the atom.
Thomson's model of the atom was like a 'plum pudding' with a positively charged pudding (solid sphere) that contained negatively charged particles (electrons).
How does water enter a plant
Through the root hair cells
How can Titanium not be extracted?
Titanium cannot be extracted with carbon because Titanium carbide (TiC) is formed rather than Titanium; similar to Vanadium, Tungsten and Molybdenum. It cannot be extracted by electrolysis as it has to be very pure.
Why are the rings of cartilage in the trachea incomplete
To allow food to pass down the trachea easily
Why do cells need to communicate with each other
To control processes inside the body and to respond to changes in the environment
Why do muscle fibres contain a lot of ATP?
To provide the energy needed for muscular contractions.
What is the purpose of photolysis during the light dependent stage?
To replace electrons lost form chlorophyll
Use of Mg(OH)2
To treat constipation and neutralise excess stomach acid safe as it is weakly alkaline
Membrane of vacuole
Tonoplast
Sampling description
Too time consuming to identify and measure the number of individuals and distribution of every species in entire area. So samples are taken and used to make estimate of total number in area. There is: -Random sampling -Systematic sampling
Why is the blood pressure in arteries greater than in capillaries
Total cross sectional area of the capillaries is greater than the arteries that supply them.
What makes up the protective wall of pollen grains
Tough exine Thinner intine
Why are haloalkanes not used any more?
Toxicity, detrimental effects on the atmosphere
Function of NAD and FAD
Transfer hydrogen from one molecule to another -so can reduce or oxidise
Phloem function
Transports substances produced by plants, such as sucrose and amino acids, to all parts of the plant
Xylem function
Transports water and mineral ions from roots to all parts of plant.
Treatment for TB
Treatment of these four antibiotics can completely cure the disease: 1. ISONIAZID 2. RIFAMPICIN 3. PYRAZINAMIDE 4. ETHAMBUTOL
What products from the calvin cycle is used to make useful organic substances e.g. glucose?
Triose phosphate Glycerate-3-phosphate
Ribulose bisphosphate (5C) and carbon dioxide combine to form...
Triose phosphate (3C)
What is Termination two of Methane?
Two chlorine react to form a chlorine molecule, if the UV is removed.
Why does the link reaction occur twice for every glucose molecule?
Two pyruvate molecules made for every glucose molecule, so link reaction and krebs cycle happen twice for every glucose molecule: *2 acetyl coenzyme Ago into Krebs cycle. *2 CO2 as waste product of respiration. *2 reduced NAD for oxidative phosphorylation.
How does the kidney make urine?
Two-stage process: 1. ULTRAFILTRATION: Involves filtering small molecules, including urea, out of the blood and into Bowman's capsule. From Bowman's capsule the molecules flow along the nephron towards the ureter. 2. SELECTIVE REABSORPTION: Any useful molecules from fluid in nephron reabsorbed into blood in capillaries
Mutation
Unpredictable change in the genetic material of an organims
Why do unsaturated lipids have lower melting points than saturated lipids
Unsaturated fatty acid chains can't be packed as closely as straight molecules, so these fats are less dense. So triglycerides with unsaturated fatty acids melt at lower temperatures than those with saturated fatty acids.
Stem cell
Unspecialised cells that can develop into any type of cells.
Stem cells
Unspecialised cells that retain the ability to become a wide variety of specialized cells
What is the main nitrogenous excretory product?
Urea [CO(NH2)2]
Treatment for malaria
Use antimalarial drugs
Test for starch
Use iodine in potassium iodide solution Positive result = red brown -> blue black
How do the structures of triglycerides relate to their function
Used as energy storage molecules: 1. Long hydrocarbon tails of the fatty acids contain lots of chemical energy - lots of energy released when they're broken down. 2. They're insoluble, so don't cause water to enter cells by osmosis
When is systematic sampling used
Used for example to investigate how species are distributed in an area where the physical conditions such as: • Altitude • Soil moisture content • Soil type • Soil pH Light intensity ...change
How is the substance creatine used by the body?
Used in muscles in the form of creatine phosphate, where it acts as an energy store.
Ways of minimising heat loss in a calorimeter
Using a draught screen, mineral wool, lid, enclosing the flame, burning in pure oxygen not air. and using a bomb calorimeter, which is the most accurate piece of apparatus, so it is used to find data book values
What are Van der Waals forces?
Van der Waals forces cause all atoms and molecules to be attracted to one another. They're caused by temporary dipoles which occur when the moving electrons within a charge cloud are more to one side than the other. Larger molecules or molecules with a greater surface area have more Van der Waals forces.
Group 2 Metals + Water
Vigour increases down group 2 hydroxides are produced X + 2H2O (l) → X(OH)2(aq) + H2(g) fizzing and effervescence increases down the group solution heats up more down the group (move exothermic) metal dissolves faster down the group so the amount of white precipitate reduces down the group
Respiratory quotient
Volume of CO2 produced when the substrate is respired divided by the volume of oxygen consumed, in a set period of time.
Why is it important to control water potential of blood?
WP HIGH IN BLOOD: Water moves into cells by osmosis causing swelling and cells may burst. WP LOW IN BLOOD: Water from cell moves into blood via osmosis, causing metabolic reactions to slow or stop
What conditions are needed for Nucleophilic substitution by CN.
Warm, Aqueous alcoholic KCN The CN acts as a Nucleophile, forming an (e)nitrile.
Photo respiration
Wasteful reaction in which RuBP combines with oxygen instead of carbon dioxide (catalysed by rubisco) ; it is favoured by high temperatures and high light intensity.
Industrial Alkene Hydration to form alcohols
Water +conc. H3PO4 catalyst, 1 step reaction, no waste products (high atom economy), high temperatures and pressures 300-600 degrees and 70 atm Seperation of products is easier and cheaper
Transpiration maintains the...
Water potential gradient
What is the resolution of a microscope determined by?
Wavelength of waves being used to view the specimen
Casparian strip
Waxy, impermeable strip found in the cell walls of the endodermis cells in the roots, that blocks the pathway of water in the apoplast pathway.
Acidic buffer
Weak acid and a salt of a weak acid. (Or a weak acid partially neutralised with a strong base)
Reversible inhibition
Weak hydrogen bonds or ionic bonds are formed between inhibitor and the enzyme, which can be easily removed
Ionic bonds
Weak interactions between positive and negative charges on different parts of the molecule
Hydrophobic and hydrophilic interactions
When hydrophobic groups are close together in the protein they clump together. So hydrophilic groups are more likely to be pushed to the outside, which affects how the protein folds up into final structure.
Catalyst poisoning
When impurities in a reaction mixture bind to a catalyst's surface, blocking reactants from being adsorbed and reducing the effectiveness of the catalyst.
How can mutations be inherited?
When mutation occurs in somatic cells, cannot be passed on to offspring by sexual reproduction. Mutations in cell that divides to form gamete. Gamete with mutations fuses to form zygote. Zygote cell divides repeatedly to form new organism in which all the cells contain the mutated genes.
Plasma cell
When stimulated by antigens, plasma cells produce large amounts of antibodies which bind to a pathogen and cause it to become inactivated or destroyed.
What is a dipole?
When there is a large difference in electronegativity in a polar bond so there is a large difference in charge between the two atoms caused by a shift in electron density in the bond.
Anabolic reaction
When two substrate molecules need to be joined: being attached to the enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily
What is Incomplete combustion?
Where fuels react exothermically with limited oxygen to produce carbon and carbon monoxide.
What is Complete combustion?
Where fuels react with excess oxygen exothermically to release a relatively large amount of energy per gram of fuel, alongside carbon dioxide.
Source (translocation)
Where substance is made = in high concentration Part of plant where assimilates enter the phloem
Sink (tranlocation)
Where the substance is used up = in low concentration Part of plant where assimilates leave the phloem
What is Termination?
Where the total number of free radicals decreases as no more are produced.
When is penicillin active on bacteria
While they are growing
Leukocytes
White blood cells
Stem cells in the bone marrow (explain)
White blood cells in the blood originate form stem cells in the bone marrow. MYELOID STEM CELLS: -platelets -neutrophils -monocytes LYMPHOID STEM CELLS: - T- and B-lymphocytes The stem cells divide and differentiate to produce many matured blood cells.
Substance produced when Al3+ metal aqua ion reacts with dilute NaOH
[Al(H2O)3(OH)3] White Ppt
Substance produced when Al3+ metal aqua ion reacts with NaOH in excess
[Al(OH)4]-
Substance made when [Co(H2O)6]2+ reacts with dil. NH3
[Co(H2O)4(OH)2] Blue Ppt
Substance made when [Co(H2O)6]2+ reacts with dil. NaOH
[Co(H2O)4(OH)2] Blue Ppt
Formula of Co2+ metal aqua ion
[Co(H2O)6]2+
Product when [Co(NH3)6]2+ is left to stand in air.
[Co(NH3)6]3+ Dark Brown Soln
Substance made when [Cr(H2O)6]3+ reacts with sodium carbonate. (Formula, colour, state)
[Cr(H2O)3(OH)3] Grey Green Ppt CO2 - effervescence
Substance made when [Cr(H2O)6]3+ reacts with XS NaOH (Formula, colour, state)
[Cr(OH)6]3- Green, Soln,
Substance made when [Cu(H20)6]2+ reacts with dil. Ammonia.
[Cu(H20)4(OH)2] blue ppt
Substance made when [Cu(H20)6]2+ reacts with dil. Sodium Hydroxide.
[Cu(H20)4(OH)2] blue ppt
Formula of Cu2+ metal aqua ion in solution
[Cu(H2O)6]2+
Substance made when [Cu(H20)6]2+ reacts with conc. HCl
[CuCl4]2- Green Soln
Substance made when [Fe(H2O)6]2+ reacts with ammonia in excess
[Fe(H20)3(OH)3] brown ppt due to oxidation
Substance made when [Fe(H2O)6]2+ reacts with dil ammonia
[Fe(H20)4(OH)2] Green Ppt
Substance made when [Fe(H2O)6]2+ reacts with dil sodium hydroxide
[Fe(H20)4(OH)2] Green Ppt
Substance made when [Fe(H2O)6]3+ reacts with dil ammonia
[Fe(H2O)3(OH)3] Brown ppt
Substance made when [Fe(H2O)6]3+ reacts with dil. sodium hydroxide
[Fe(H2O)3(OH)3] Brown ppt
Buffer equation
[H+] = Ka [acid] / [salt]
Acid dissociation constant of a weak acid (Ka)
[H^+] [X^-] / [HX]
Simplification of Ka if a weak acid only is present
[H^+]^2 / [HA]
1. How does temperature affect levels of RuBP, GP and TP?
a. All reactions in Calvin cycle catalysed by enzymes b. Low temperatures = enzymes work slower = slower reaction = levels of all fall c. High temperatures = same effect as enzymes get denatured
1. What factors can limit photosynthesis?
a. Carbon dioxide b. Temperature c. Light intensity
Optimum conditions for photosynthesis:
a. High light intensity of a certain wavelength i. Light is needed to provide energy for light dependent reaction - higher intensity of light = more energy provided ii. Only certain wavelengths of light are absorbed by certain photosynthetic pigments b. Temperature - 25 degrees Celsius i. Photosynthesis involves enzymes (e.g. ATP synthase, rubisco). Below 10 = inactive. Above 45 = denatured. ii. At high temperatures, stomata close to avoid losing too much water, causing photosynthesis to slow down as less CO2 enters the leaf. iii. Temperature affects rate of light independent reaction - molecules have higher KE, collide more often, more successful collisions. Rate of light dependent reaction not affected by temperature as its dependent on light energy. c. Carbon dioxide - 0.4% i. CO2 makes up 0.04% of gases in atmosphere ii. Increasing to 0.4% gives higher rate of photosynthesis but any higher and stomata start to close. d. Constant supply of water i. Too little - stomata close, preventing CO2 entering ii. Too much - soil becomes waterlogged (reducing uptake of magnesium for chlorophyll a)
1. How does carbon dioxide concentration affect levels of RuBP, GP and TP?
a. Low CO2 levels = conversion of RuBP to GP is low (less CO2 to combine with RuBP to make GP) b. So levels of RuBP will rise (still being made) c. Levels of GP and TP fall (used up to make RuBP)
1. How does light intensity affect levels of RuBP, GP and TP?
a. Low light intensity = products of light dependent stage (reduced NADP and ATP) will be in short supply b. So conversion of GP to TP and RuBP slow c. So GP levels increased (still being made) d. TP and RuBP levels decreased (used up to make GP)
1. How can increased CO2 concentration increase plant growth?
a. More CO2 = greater rate of photosynthesis = more glucose produced b. = Greater respiration = more ATP for DNA replication, cell division and protein synthesis
1. Why can't photosynthesis occur at high CO2 concentrations?
a. Stomata start to close
How is the structure of a chloroplast adapted to its function?
a. The chloroplast envelope keeps the reactants for photosynthesis close to their reaction sites. b. The thylakoids have a large surface area to allow as much light energy to be absorbed as possible. c. Many ATP synthase molecules are present in the thylakoid membranes to produce ATP in the light-dependent reaction. d. The stroma contains all the enzymes, sugars and organic acids for the light-independent reaction to take place.
1. How can limiting factors of photosynthesis be investigated using pond weed?
a. Use capillary tube, vary the limiting factor, allow time for photosynthesis, measure length of O2 bubble produced in capillary tube.
1. Why might there be differences in plant growth when providing heat with an electric heater and wood fire?
a. Wood fire increases temperature more / increases CO2 concentration
Unlike water transport in the xylem, phloem transport is an....
active process
Advantages of Electrolysis
can be used for metals more reactive than carbon
Give an example of a reagent which could be used to show that the reducing ability of bromide ions is different from that of chloride ions
conc. H2SO4
Why are polyalkenes unreactive?
due to strong C-C and C-H bonds
Fermentation of Glucose to produce ethanol
glucose 2 ethanol + 2 carbon dioxide
Percentage saturation of Hb with oxygen is linked with...
how much O2 is released or taken in by the Hb molecules.
Shape of active site...
is very precise and maintained by the tertiary structure of the protein
How can racoons pose a threat to biodiversity?
may compete with other species for, food/ habitat ; 2 may be predators of other species ; 3 may spread disease to other species ; 4 may reduce population sizes / cause extinction of other species ;
Species density
measure of how many individuals there are per unit area (Number of individuals counted / total area of all quadrats)
How would a value for ∆Hc, differ if it was measured with a reactant in the gaseous state compared to a reactant in the liquid state
more exothermic and negative, as heat is released when water vapour condenses, so less heat is needed to vapourise water. also molecules have more energy in the gaseous state.
Specific base pairing means that the mRNA end up as an exact...
reverse copy of the template DNA section.
Calculating relative atomic mass
relative atomic mass = isotopic masses x percentages/total percentage
How many orbitals do each-sub shell contain?
s - 1 p - 3 d - 5 f - 7
Stereoisomer
same structural formula, atoms arranged differently in space
Shape of cisplatin
square planar
ϴ in ∆Hϴ
standard conditions
Cl2 uses
to kill bacteria, health benefits outweigh toxicity
whiy is HCl is used in the sulphate test
to remove carbonate ions impurities from sulphate ion salts as they would react with BaCl2 to give BaCO3 which is an incorrect result HCl + Na2CO3 →2NaCl + H2O + CO2 - fizzing - carbonate ions are removed
What metal is exacted using hydrogen?
tungsten: WO3 Temp >900
Water moves down a...
water potential gradient
At approximately which magnification is light microscopy not suitable because the resolution becomes too low?
x1500
Xylem vessel elements are arranged in long lines by being joined end to end to form...
xylem vessels
Line transect procedure
• Lay out measuring tape in straight line = transect line. • Sample organisms that are present along the line. • Record identity of organisms touching the line at set distances. Transects used to detect changes in community composition along a line across one or more habitats.
Steps to reduce antibiotic resistance
• Using antibiotics only when appropriate and necessary; not prescribing for viral infections • Reducing the number of countries in which antibiotics are sold without a doctor's prescription • Avoiding the use of wide-spectrum antibiotics and using instead an antibiotic specific to the infection • Making sure that patients complete their course of medication • Making sure patients do not keep unused antibiotics for self-medication in the future • Changing the type of antibiotics prescribed for certain diseases so that the same antibiotic is not always prescribed for the same disease The more we misuse antibiotics, the greater the selection pressure we exert on bacteria to evolve resistance to them.
Why aren't viruses included in the classification system?
• Viruses don't have cellular structures. • Only reason viruses are considered as living organisms is due to them having particles made of proteins and nucleic acids that are found in all cellular organisms. • Viruses are not found in the classification system as they don't have any of the features traditionally used for classification.
