Edexcel GCSE B2
How can mutations be harmful?
A mutation could cause a genetic disorder, for example cystic fibrosis
How can mutations be beneficial?
A mutation could produce a new characteristic that is beneficial to an organism e.g. resistance in bacteria
What is respiration?
A process used by all living organisms that releases the energy in organic molecules
What is a gene?
A section of a molecule of DNA that codes for a specific protein
Describe the process of genetic engineering
A useful gene is removed from one organisms chromosome using enzymes and then another organism's DNA is cut and the gene is inserted
How are minerals absorbed?
Active transport in the roots
What are the five bases?
Adenine, Thymine, Guanine, Cytosine, Uracil
Does anaerobic or aerobic respiration produce more energy?
Aerobic respiration
What is growth?
An increase in size, length or mass
What is cloning an example of?
Asexual reproduction that produces genetically identical copies
Why are there gaps in the fossil record?
Because fossils do not always form, because soft tissue decays, because may fossils are yet to be found
What are three examples of the advantages of genetic engineering?
Beta carotene in golden rice to reduce vitamin A deficiency in humans, the production of human insulin by genetically modified bacteria, the production of herbicide-resistant crop plants
What bacteria are in probiotics
Bifidobacteria, lactobacillus
What is the word equation for photosynthesis?
Carbon dioxide+water -> glucose+oxygen
What is the formula for cardiac output?
Cardiac output = stroke volume x heart rate
What processes make a plant grow?
Cell differentiation, cell division, cell elongation
What processes make animals grow?
Cell division and cell differentiation
What are the components of an animal cell?
Cell membrane, mitochondria, cytoplasm, nucleus
What is a cell wall made out of?
Cellulose
What are the components of a plant cell?
Chloroplast, large vacuole, cell wall, cell membrane, mitochondria, cytoplasm, nucleus
Name the components of a bacterial cell
Chromosomal DNA, Plasmid DNA, flagellum, cell wall
What are the disadvantages of cloning?
Cloning mammals leads to a reduced gene pool, cloned animals mightn't live as long
What is the function of a large vacuole?
Contains cell sap (sugar and salts)
What are the advantages of adult and embryonic stem cell research?
Curing disease, creation of specialised cells
Name three reactions enzymes catalyse
DNA replication, protein synthesis, digestion
What can stem cells in the embryo do?
Differentiate into any type of cell, but cells lose this ability as the animal matures
When does mitosis occur?
During growth, repair and asexual reproduction
What is an ethical disadvantage of embryonic stem cell research?
Embryos have the potential for human life
What is the word equation for respiration?
Glucose+oxygen->Carbon dioxide+Water
What happens at fertilisation?
Haploid gametes combine to form a diploid zygote
How can an enzyme be denatured?
If it is too hot or the pH is too high or low the bonds holding the enzyme together break
What possible bad implications did the human genome project have?
Increased stress, gene-ism, discrimination by employers and insurers
How are cells grouped?
Into tissues
What is the function of a red blood cell?
It contains haemoglobin which combines with oxygen to become oxyhaemoglobin, the opposite happens in tissue cells to release the oxygen to cells
What is the function of the cell membrane?
It holds the cell together and controls what goes in and out
What is the structure of a red blood cell?
It is a biconcave disc to give a large surface area for absorbing oxygen, it has no nucleus to allow room for more oxygen
What happens to lactic acid?
It is broken down by oxygen
What is the function of cytoplasm?
It is where most of the chemical reactions happen
Why does the left ventricle have a thicker wall than the right ventricle?
It need to produce more power to pump blood around the whole body
How are veins adapted?
Less thick walls and muscle, large lumen, valves
What did Watson and Crick do?
Make a model of DNA where all the pieces fitted together
How does the anatomy of the pentadactyl limb provide scientists with evidence for evolution?
Many species have a similar bone structure which implies they came from the same ancestor
What does the vena cava do?
Move deoxygenated blood from the body into the right atrium
What does the pulmonary artery do?
Move deoxygenated blood from the right ventricle into the lungs
What does aorta do?
Move oxygenated blood from the left atrium around the body
What does the pulmonary vein do?
Move oxygenated blood from the lungs to the left atrium
Why does heart rate and breathing rate increase with exercise?
Muscles need more energy
What transports sugars?
Phloem
What possible good implications did the human genome project have?
Predict and prevent diseases, develop new and better medicines, Accurate diagnosis, improve forensic science
What do the right atrium and ventricle do?
Pump deoxygenated blood
What do the left atrium and ventricle do?
Pump oxygenated blood
What are the advantages resulting from cloning?
Reducing the organ shortage, greater understanding of the development of the embryo, ageing and age related disorders, preserve endangered species
What are the five stages of cloning mammals?
Removal of diploid nucleus from a body cell, enucleation of egg cell, insertion of diploid nucleus into enucleated egg cell, stimulation of the diploid nucleus to divide by mitosis, implantation into surrogate mammals
What is the function of the mouth?
Saliva moistens food and produce amylase which breaks down starch, food is chewed to forma bolus before being swallowed
Why is bile needed to emulsify fats?
So that fat is in tiny droplets and so digestion will happen faster
What factors affect enzyme action?
Temperature, substrate concentration, pH
How does the order of bases determine the order of amino acids in a protein?
The amino acids are joined to tRNA which bonds in the order of the mRNA
How does loss of water vapour drive transpiration?
The loss of water creates a shortage in the leaf so more water is drawn up to replace it through xylem
What is transcription?
The mRNA forming on the DNA
Define diffusion
The movement of particles from an area of high concentration to an area of lower concentration
Define Osmosis
The movement of water molecules from an area of higher concentration of water to an area of lower concentration of water through a partially permeable membrane
Why is bile needed to neutralise stomach acid?
The pH is too high for enzymes in the small intestine so it has to be reduced so they can work
What are the risks of cloning?
The process often fails, Clones often have genetic defects, Cloned animals have unhealthy immune system
Describe the stages of protein synthesis
The production of complementary mRNA strand in the nucleus, the attachment of the mRNA to the ribosome, the coding by codons in the mRNA for specific amino acids, the transfer of amino acids to the ribosome to tRNA, the linking of amino acids to form polypeptides
Describe the division of a cell by meiosis
The production of four daughter cells, each with half the number of chromosomes, and this results in the formation of genetically different haploid gametes
Describe the division of a cell by mitosis
The production of two daughter cells, each with identical sets of chromosomes in the nucleus to the parent cell, and this results in the formation of two genetically identical diploid body cells
What is translation?
The tRNA joining the mRNA
What are enzymes highly specific for?
Their substrate
What is the function of chloroplasts?
They are where photosynthesis occurs and they contain chlorophyll
What is the function of the mitochondria?
They are where the reactions for respiration take place
What is the function of Plasmid DNA?
They contain genes that can be passed between bacteria
What do probiotics do?
They contain good bacteria to add to those in your stomach
What do prebiotics do?
They contain oligosaccharides which feed the bacteria in your stomach
How can mutations be neither harmful or beneficial?
They don't affect a protein's function
Why during vigorous exercise do muscles respire anaerobically
They don't receive sufficient oxygen to respire aerobically
How are villi adapted?
They have a large surface area for quick absorption, they have a single layer of cells so food diffuses quickly, they have a capillary network to allow for quick absorption
How are roots adapted to absorb water?
They have millions of hair cells giving them a large surface area
What is the function of platelets?
They help the blood clot at a wound
How can microscopes be used to study cells?
They make the image bigger
What is the function of white blood cells?
They produce antibodies and antitoxins, they eat unwelcome microorganisms
What do plant stanol esters do?
They reduce cholesterol
How is an artery adapted?
Thick walls and muscle to cope with high pressure
What is the function of the large intestine?
To absorb excess water
What is the role of lipase?
To digest fats to fatty acids and glycerol
What is the role of proteases (pepsin)
To digest proteins to amino acids
What is the role of carbohydrases (amylase)
To digest starch to simple sugars
Why does the heart have valves?
To prevent backflow
What is the function of the pancreas?
To produce protease, amylase, lipase which are released into the small intestine
What is the function of the small intestine?
To produce: protease, amylase, lipase. To absorb the food
What is the function of the stomach?
To pummel the food with it's muscular walls, to produce protease and pepsin, To produce hydrochloric acid to kill bacteria and give the right pH for protease
What is the function of the gall bladder?
To store bile before it's released into the small intestine
What is the function of a cell wall?
To support a cell
What is the function of the oesophagus?
To transport food from the mouth to the stomach by peristalsis
What do arteries do?
Transport blood away from the heart
What do veins do?
Transport blood to the heart
Describe a DNA molecule
Two strands coiled yo form a double helix linked by a series of complementary bases joined by weak hydrogen bonds
Who discovered the structure of DNA?
Watson, Crick, Franklin, Wilkins
What did Franklin and Wilkins do?
Work out the helical structure through directing X-rays onto crystallised DNA
What transports water and minerals?
Xylem
Describe enzymes
biological catalysts
What is the breaking down of lactic acid by oxygen called?
excess post-exercise oxygen consumption (EPOC)
What do capillaries do?
exchange materials with tissues
What is the word equation for anaerobic respiration?
glucose -> lactic acid
How does the human circulatory system facilitates respiration?
glucose and oxygen diffuses from capillaries into respiring cells, carbon dioxide diffuses from respiring cells into capillaries
How are organs grouped?
into organ systems
How are tissues grouped?
into organs
What is the function of the nucleus?
it contains DNA that controls the cell
What is the function of Chromosomal DNA?
it controls the cell's activities and replication
Describe each protein
it has its own specific number and sequence of amino acids, resulting in different-shaped molecules that have different functions, including enzymes
What is the function of plasma?
it transports: the other parts of the blood, glucose and amino acids, Carbon dioxide, urea, hormones, antibodies and antitoxins
How is the structure of a leaf adapted for photosynthesis?
large surface area, containing chlorophyll in chloroplasts to absorb light, stomata for gas exchange (carbon dioxide, oxygen and water vapour)
What are the limiting factors of photosynthesis?
light intensity, CO2 concentration, temperature
What is the direction of blood flow in the heart?
pulmonary vein to left atrium to left ventricle to aorta to vena cava to right atrium to right ventricle to pulmonary artery to pulmonary vein
What model describes how enzymes work?
the lock and key model
What is the function of the liver?
to produce bile which neutralises stomach acid and emulsifies fat
What happens in peristalsis?
waves of circular muscle push the food along whilst waves of longitudinal muscles run in front of the food
