Biology Paper 2 November 2024

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Answer this when you sit the paper.

1. Athe ability to tell two close objects apart, while resolution is the number of times larger the image is than the specimen
2. Bthe sharpness of the image produced, while resolution is the brightness of the light passing through the specimen
3. Cthe thickness of the specimen that can be viewed, while resolution is the wavelength of the light used
4. Dthe number of times larger the image is than the specimen, while resolution is the ability to tell two close objects apart

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Answer this when you sit the paper.

1. Atransfer RNA molecules can no longer pick up their own amino acids
2. Bthe two ribosomal subunits fuse permanently and cannot be separated
3. Cthe messenger RNA can no longer be transcribed from the DNA inside the nucleus
4. Dno peptide bonds are formed, so the polypeptide chain cannot be extended

1. Aremoving the introns from the messenger RNA transcript before it leaves the nucleus
2. Bcopying one strand of the DNA to make a molecule of messenger RNA in the nucleus
3. Cfolding the chain, adding carbohydrate or phosphate groups, and joining chains together
4. Dreading each of the codons of the messenger RNA and matching every one with a transfer RNA anticodon

Answer this when you sit the paper.

1. Apassing a fine tube through the mother's mouth and stomach to reach the wall of the uterus
2. Busing an ultrasound scan to locate the fetus, then withdrawing amniotic fluid through a hypodermic needle
3. Cremoving a small piece of the fetus's skin through a cut made in the wall of the abdomen
4. Dtaking a sample of the mother's own blood from a vein in her arm and then separating out the fetal cells from it

1. Amakes certain that the child will be born free of any inherited disorder once the test has been done
2. Bexplains the procedure and the risks, and lets the couple make an informed decision
3. Creplaces the need for the screening test itself in families with a history of the disorder
4. Ddecides on the couple's behalf whether the pregnancy should be allowed to continue

1. Athe solubility of each pigment in the solvent and its affinity for the paper
2. Bthe colour of each pigment and the intensity of the light in the laboratory
3. Cthe temperature of the leaf before extraction and the age of the plant used
4. Dthe volume of solvent used in the tank and the number of pigments in the extract

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1. AN chlorophyll a, M chlorophyll b, Y carotene, X xanthophyll
2. BN chlorophyll b, M chlorophyll a, Y xanthophyll, X carotene
3. CN carotene, M xanthophyll, Y chlorophyll a, X chlorophyll b
4. DN xanthophyll, M carotene, Y chlorophyll b, X chlorophyll a

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1. Abreaking down starch stored in the leaves
2. Btransporting mineral ions upwards through the xylem
3. Cattracting insects to flowers for pollination
4. Ddigesting protein in the cells of the root

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1. Aallows the capillary to contract and relax like the wall of an artery or a vein
2. Bincreases the pressure of the blood so that filtration into the tissues becomes faster
3. Cshortens the distance over which substances have to diffuse between blood and cells
4. Dprevents any plasma from leaving the blood as it passes through the capillary bed

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1. Araises the speed of the blood so that a greater volume of it passes the tissues in a given time
2. Bkeeps the blood entirely separate from the tissue fluid surrounding the cells
3. Cmakes the blood flow in the opposite direction to the fluid in the tissue spaces
4. Dgives a large total surface area and slows the blood, so there is more time for exchange

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1. Athe sodium ion concentration is low and the potassium ion concentration is high
2. Bboth sodium and potassium ion concentrations are higher than inside the axon
3. Cboth sodium and potassium ion concentrations are lower than inside the axon
4. Dthe sodium ion concentration is high and the potassium ion concentration is low

1. Aletting sodium and potassium ions diffuse freely in both directions across the membrane
2. Bpumping three sodium ions out for every two potassium ions in, leaving the inside negative
3. Cpumping equal numbers of sodium and potassium ions in opposite directions across it
4. Dpumping three potassium ions out for every two sodium ions in, leaving the inside positive

1. Araises the resistance to the flow of ions, so the impulse travels slower
2. Bremoves the myelin sheath, so the impulse has to travel along the whole axon
3. Creduces the number of sodium channels, so fewer impulses can be carried
4. Dlowers the resistance to the flow of ions, so the impulse travels faster

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1. AA oestrogen, B luteinising hormone
2. BA follicle stimulating hormone, B testosterone
3. CA testosterone, B follicle stimulating hormone
4. DA luteinising hormone, B oestrogen

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Answer this when you sit the paper.

1. Ainhibits the secretion of FSH and LH by the anterior pituitary, so sperm production falls
2. Bdestroys the Sertoli cells of the testis, so no sperm can be nourished as they develop
3. Craises the secretion of FSH and LH by the anterior pituitary, so far too many sperm are made
4. Dblocks the sperm ducts so that sperm made in the testis cannot leave the body

1. Ait makes the man permanently sterile and cannot be reversed once treatment stops
2. Bsome men reject it as interfering with procreation or with their religious beliefs
3. Cit is far cheaper to produce than any of the contraceptives already available
4. Dit is the only method of contraception that has ever been tested on human volunteers

Answer this when you sit the paper.

Answer this when you sit the paper.

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Answer this when you sit the paper.

1. Abinds oxygen and keeps conditions anaerobic, since nitrogenase is inactivated by oxygen
2. Bgives the root nodule its pink colour, which attracts more bacteria to the root
3. Ctransports the ammonium ions produced away from the nodule into the xylem sap
4. Dcarries oxygen straight to the bacteria so that nitrogenase can oxidise the nitrogen gas

1. Asugars, which are respired to supply the ATP that nitrogen fixation requires
2. Bnitrate ions, which the bacteria reduce to ammonium ions inside the nodule
3. Cchlorophyll, which the bacteria use to photosynthesise inside the root nodule
4. Durea, which the bacteria break down to release the ammonia they need

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1. Aby observable characteristics, with every characteristic given equal weight
2. Bby their evolutionary history, using fossil evidence to trace common ancestors
3. Cby the habitat in which they live, regardless of how they are built
4. Dby their economic importance to the people who live alongside them

1. Awas abandoned entirely by biologists once DNA sequencing became widely available to them
2. Bcan only ever be used for the animals, since plants leave behind no fossils of any kind at all
3. Cneeds evolutionary relationships that are hard to establish when fossil evidence is scarce
4. Dignores the observable characteristics of an organism and uses its habitat instead

Answer this when you sit the paper.

Answer this when you sit the paper.

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1. Aboth are projected to fall, but the incidence rate falls by more than the death rate does
2. Bboth are projected to fall, but the death rate falls by more than the incidence rate does
3. Cthe incidence rate is projected to fall while the death rate is projected to rise
4. Dthe death rate is projected to fall while the incidence rate stays at the same level

1. Aimproving health delivery, vaccinating widely and raising public awareness of treatment
2. Btreating patients only once the symptoms have become severe enough to be obvious
3. Cisolating for life every person who has ever come into contact with a patient who is infected
4. Dwaiting for the bacterium to become less harmful as it evolves alongside its human host