Biology Paper 3 June 2017

1. Aheld in a closed chamber and sprayed with a mist of nutrient solution.
2. Bleft standing in a tank of aerated nutrient solution throughout growth.
3. Cplanted in a shallow layer of sterile soil fed by a drip line.
4. Danchored in a bed of gravel that is flooded and drained on a cycle.

1. Aneeds no supply of mineral nutrients because the roots absorb from air.
2. Brecirculates a small volume of solution, so far less water is used.
3. Cremoves the need to control the temperature around the roots at all.
4. Dallows the crop to be grown in the open field without any structure.

1. Aproduction of disease free seed potato tubers.
2. Bstorage of harvested grain under controlled humidity.
3. Cextraction of essential oils from harvested leaves.
4. Dfermentation of plant sugars to produce ethanol.

Tap to enlarge

1. Aexhaust gas leaving the top draws the culture upwards behind it.
2. Bperforated pipes at the base release bubbles that rise and carry liquid with them.
3. Cvessel itself is rocked slowly so that the contents wash from side to side.
4. Dculture is pumped out at the base by an impeller and returned through the top of the vessel.

1. Acool the culture below the temperature that the chosen organism needs in order to grow.
2. Bdissolve too slowly to meet the oxygen demand of the culture.
3. Craise the pressure inside the vessel above its safe working limit.
4. Dcarry in microorganisms that compete with the culture and spoil the product.

Tap to enlarge

Answer this when you sit the paper.

Tap to enlarge

1. Aprevent the organisms in the culture escaping into the environment.
2. Braise the pressure inside the vessel so that a greater mass of oxygen dissolves.
3. Ccool the gases so that water vapour condenses and drains back.
4. Dmeasure the volume of carbon dioxide the culture has released.

1. Athe plants grow so fast that a pathogen has no time at all to become established on them.
2. Bthe roots produce more lignin and so become physically harder to invade.
3. Ca pathogen has no film of standing water in which to spread from root to root.
4. Dthe mist is applied at a pressure high enough to kill any fungal spores.

1. Araise the yield of a crop by selecting and sowing the largest seeds each season.
2. Bconserve alleles of wild relatives that plant breeders may need later.
3. Cincrease the rate at which new mutations arise in a crop species.
4. Dprovide a store of harvested grain to be sold when prices improve.

1. Aseeds are only viable in the season in which they were collected.
2. Bsome seeds are dead, some are damaged and some are still dormant.
3. Call the seeds germinate but the seedlings die before they can be counted.
4. Dgermination testing destroys a fixed proportion of every sample by law.

Answer this when you sit the paper.

1. Asoaking the seeds in concentrated sulphuric acid
2. Btreating the seeds with a gibberellin solution
3. Capplying abscisic acid to the seed coat
4. Dchilling the imbibed seeds for several weeks

1. Acomparing the mass of the sample before and after the substance has been removed from it by a chemical reaction.
2. Bheating the sample and reading the wavelength of the light it emits.
3. Cpassing the sample through a column that separates it by molecular size.
4. Dusing a biological molecule that binds the substance and a transducer that converts that event into an electrical signal.

Answer this when you sit the paper.

1. Asterilise instruments before a surgical operation.
2. Bculture bacteria taken from an infected wound.
3. Cmeasure the concentration of glucose in a drop of blood.
4. Dsequence the bases along a length of human DNA.

1. Apassed slowly over a bed of stones on which a film of algae grows.
2. Ballowed to stand undisturbed in a large tank so that the suspended solids settle and are drawn off.
3. Cheld in a sealed tank without oxygen so that methane is produced.
4. Dmixed with a floc of aerobic microorganisms and aerated so that organic matter is oxidised.

Answer this when you sit the paper.

1. Aconvert the carbon in the waste directly into humus without releasing any gas.
2. Bdecompose the organic waste, releasing mineral nutrients and heat.
3. Cfix atmospheric nitrogen into the heap so that its nitrogen content rises.
4. Dprotect the heap from decay by outcompeting the organisms that cause it.

1. Aabsorb the metal into their cells and are then harvested and burnt.
2. Bgrow into the rock and split it mechanically, so that the metal can then be picked out by hand.
3. Coxidise the sulphide, releasing the metal as ions into a solution that is drained off.
4. Dreduce the metal ions in the ore to the pure metal in a single step.

Answer this when you sit the paper.

1. Atreating a mixed antibody preparation to remove all but one kind.
2. Bculturing plasma cells taken from an immunised animal, which divide indefinitely.
3. Cextracting antibodies from the serum of an animal injected with the antigen.
4. Dfusing a B lymphocyte that makes the wanted antibody with a myeloma cell.

Answer this when you sit the paper.

1. Aan unvaccinated person acquires antibodies from those around them.
2. Bthe pathogen mutates into a harmless form once most hosts are immune.
3. Cthe vaccine itself spreads from person to person in the same way that the disease would.
4. Dtoo few susceptible hosts remain for a chain of transmission to be sustained.

1. Aa bacterium.
2. Ba fungus.
3. Ca protozoan.
4. Da virus.

1. Amature xylem vessel.
2. Bripening fruit wall.
3. Croot cortex of an old root.
4. Dshoot apical meristem.

1. Adried in a warm oven so that any fungal spores on it are killed.
2. Bfrozen and thawed so that the outer cells rupture and fall away.
3. Csurface sterilised in a disinfectant such as sodium hypochlorite, then rinsed in sterile water.
4. Dwashed in a concentrated sugar solution so that any bacteria present on it are drawn out by osmosis.

Answer this when you sit the paper.

1. Aelectrical conductivity of the vessel wall.
2. Bratio of auxin to cytokinin in the medium.
3. Cwind speed passing over the culture.
4. Datmospheric pressure above the medium.

1. Aallows the grower to combine desirable characteristics from two parents.
2. Bproduces many plants genetically identical to a chosen parent in a short time.
3. Cproduces plants that are larger than any that could be grown from seed.
4. Dproduces variable offspring, so a population can adapt to a new disease.

1. Ais always harmful, whereas a chromosomal mutation is always neutral.
2. Balters the base sequence within a single gene rather than the number or structure of chromosomes.
3. Carises only during meiosis, whereas a chromosomal mutation arises only during mitosis of body cells.
4. Dcan be inherited, whereas a chromosomal mutation is always lost with the individual.

Answer this when you sit the paper.

Tap to enlarge

1. Agrafting the two varieties together so that their tissues fuse before flowering.
2. Bremoving the anthers from the chosen female parent, bagging the flowers, then transferring pollen from the other parent by hand.
3. Cspraying the flowers of both parents with a growth regulator so that they stay closed and cannot be reached by any insect.
4. Ddusting both parents with an insecticide to keep all insects away from them.

Answer this when you sit the paper.

Tap to enlarge

1. Araise the mutation rate so that new characters appear in the offspring.
2. Ballow the hybrid trees to grow large enough for all of their fruit to be picked and weighed.
3. Cbring all three wanted characters together and make the plants breed true for them.
4. Dgive the environment time to induce the wanted characters in the hybrid.

1. Aan autosomal recessive character.
2. Ba sex linked dominant character.
3. Ca sex linked recessive character.
4. Dan autosomal dominant character.

Answer this when you sit the paper.

1. Amakes the skin more permeable, so salt diffuses outwards from the blood.
2. Bcauses the sweat glands to secrete a much larger volume of sweat than normal, so a great deal more salt is lost.
3. Cis a chloride channel, so chloride ions are not reabsorbed from the sweat duct and sodium ions stay with them.
4. Dis an enzyme that normally breaks down the salt present in the secreted sweat.

1. Acontrolled by many genes acting together, each of which has a small additive effect on it.
2. Bdetermined almost entirely by the environment the individual grows in.
3. Ca quantitative character measured on a continuous scale of values.
4. Dcontrolled by one or a few genes, so the alleles give a small number of distinct classes.

1. Abody mass
2. Bintelligence
3. Cskin colour
4. DABO blood group

1. Aare carried on the same chromosome, so parental combinations appear far more often than recombinants.
2. Bare carried on the sex chromosomes, so the ratio that is obtained differs between male and female offspring.
3. Cassort independently, which gives an exact 9:3:3:1 ratio in the offspring.
4. Dmutate more frequently, so new phenotypes appear that neither parent showed.

Answer this when you sit the paper.

1. Amated to several bulls in turn, so that each of the eggs she releases is fertilised by a different bull.
2. Ballowed to conceive naturally and the calf is removed surgically at birth.
3. Cgiven hormones so that she releases many eggs, which are fertilised and the embryos placed in recipient cows.
4. Dgiven hormones so that she carries several calves to term in one pregnancy.

Answer this when you sit the paper.

1. Adelivering a working copy of the gene into the patient's cells using a vector such as a modified virus or a liposome.
2. Bgiving the patient repeated injections of the protein that the faulty gene has failed to make, for the rest of their life.
3. Cscreening embryos and implanting only those that do not carry the faulty allele.
4. Dbreeding only from unaffected members of the family in later generations.

1. Acan lead to anxiety and to discrimination by insurers or employers.
2. Bcannot be kept confidential because the law requires it to be published.
3. Cgives no information at all about the risk to the person's relatives.
4. Dalways means the person will develop the disease within a few years.

Answer this when you sit the paper.

Tap to enlarge

1. Athe requirement of the single individual with the greatest need.
2. Bthe amount below which a deficiency is certain to appear in every individual.
3. Cthe highest intake that can be taken without risk of harm.
4. Dthe mean requirement of the group, so about half of them need more than it.

1. Adiets can be planned and the adequacy of a group's intake can be assessed.
2. Bevery person can be told the exact quantity of protein that their own body needs.
3. Cfood manufacturers are obliged by law to fortify all processed foods.
4. Dthe maximum intake of every nutrient can be legally enforced.

Tap to enlarge

1. Athe group is the most physically active and so uses protein for energy.
2. Bwomen in that group have the largest body mass of any age group.
3. Cpregnancy and breast feeding raise the demand for protein.
4. Dprotein is not absorbed at all from a mixed diet after the age of 19.

1. Areplace the protein lost in the menstrual cycle each month.
2. Bcompensate for a complete loss of the ability to store amino acids.
3. Climit the loss of muscle and bone protein that comes with age.
4. Dprovide the extra protein needed for the growth of new organs.

Answer this when you sit the paper.

Answer this when you sit the paper.

1. Athe child's skin becomes thin enough for the virus to enter directly.
2. Bthe shortage of energy makes the child too weak to avoid infected people.
3. Cantibodies and lymphocytes are proteins, so too few of them are made.
4. Dmeasles is caused by a bacterium that feeds on the child's stored fat.

1. Acan still be digested by a child who has permanently lost the ability to digest protein of any kind at all.
2. Bis cheaper, so a larger number of children can be fed from the same budget.
3. Cmeets the energy demand, so the protein given is used for growth and repair rather than being respired.
4. Dstimulates the appetite, so the child eats a greater volume of food overall.

1. AT lymphocytes only
2. Bboth B and T lymphocytes
3. Cneither B nor T lymphocytes
4. DB lymphocytes only

1. Aneither B nor T lymphocytes
2. BB lymphocytes only
3. CT lymphocytes only
4. Dboth B and T lymphocytes

Answer this when you sit the paper.

1. Aantibodies against only those pathogens the mother has herself met.
2. Bantibodies that are broken down before they can reach the blood.
3. Conly the memory cells and none of the antibodies of the mother.
4. Dtoo little antibody in it to give protection against any disease at all.

1. Athe baby's gut lining takes up intact molecules by endocytosis and its protein digesting enzymes are not yet fully active.
2. Bthe baby's stomach produces no acid or enzymes of any kind at birth.
3. Cantibodies are the only proteins that are absorbed as amino acids.
4. Dthe antibodies are digested to amino acids in the stomach and then reassembled into antibodies in the baby's blood.

1. Araising the body temperature above the level enzymes can tolerate.
2. Bdividing so rapidly that they use up all the oxygen in the blood.
3. Cdamaging host cells directly and by releasing toxins.
4. Ddisplacing the body's own cells from the tissues they occupy.

1. Adissolving the wall of the capillary completely, so that plasma and blood cells flood out into the tissue together.
2. Bsqueezing between the cells of the capillary wall and then moving up a gradient of chemicals released at the site.
3. Cwaiting until a wound opens the capillary and then flowing out through it.
4. Dbeing carried there in the lymph after leaving the blood at a lymph node.

1. Alung cancer has been found in every population in which any single member has ever smoked a cigarette at all.
2. Bthe incidence of lung cancer rises with the number of cigarettes smoked and falls after a smoker gives up.
3. Ctar collected from cigarette smoke has been shown to contain carcinogens.
4. Dtumours developed in animals whose skin was painted with cigarette tar.

1. Athe death rate from lung cancer rose in the decades after cigarettes became cheap.
2. Btumours developed on the skin of animals painted repeatedly with cigarette tar.
3. Ctwins who both smoke are more alike in lung function than twins who do not.
4. Dpeople who smoke are more likely to report a cough than people who do not.

1. Amakes the bacteria that survive grow larger and so harder to engulf.
2. Bprevents the patient from ever developing immunity to any disease.
3. Cdestroys the patient's own white blood cells at the same time as it destroys the bacteria causing the infection.
4. Dgives an advantage to any resistant bacteria present, and resistance genes then spread through bacterial populations.

Answer this when you sit the paper.

1. Adissolves the surfactant lining the alveoli, so that they collapse each time the person breathes out and cannot reinflate.
2. Bnarrows the pulmonary arteries so that blood cannot reach the alveoli.
3. Cparalyses and destroys the cilia while the goblet cells enlarge and secrete more mucus, so mucus collects and becomes infected.
4. Ddestroys the elastic tissue of the alveoli so that they burst and merge.

1. Ahas some protection against malaria, so the allele is favoured where malaria is endemic.
2. Bis completely unaffected, so natural selection cannot act on the allele at all.
3. Cshows no sickling of red cells under any conditions whatever.
4. Dcannot pass the allele on to any of their children.

Answer this when you sit the paper.

1. Aremains infectious for years while appearing and feeling perfectly healthy.
2. Bsheds the virus into the air, so it is spread by ordinary breathing.
3. Ccan only be diagnosed after symptoms of AIDS have appeared.
4. Dcarries the virus in every body fluid, including sweat and saliva.

1. Aan inability to control the muscles of the eye, so vision doubles at once.
2. Bnumbness, tingling and weakness that begin in the hands and feet.
3. Cseizures that begin in the motor cortex and spread across the brain.
4. Da loss of the ability to form any new long term memories.

1. Ato break the dormancy of stored seed before sowing.
2. Bto sterilise seed trays before the seed is sown.
3. Cas a fertiliser supplying nitrogen to a rapidly growing crop.
4. Das a rooting compound applied to the base of a cutting.

1. Athe growth medium on which a plant tissue culture is raised.
2. Ba piece of tissue cut from a plant and grown on a culture medium.
3. Ca plant grown outdoors from a cutting rather than from seed.
4. Da seedling transferred from a nursery bed to the field.

1. Asoil bacteria, mycorrhizal fungi and earthworm casts.
2. Bchlorophyll, humus and washed river sand.
3. Cdigestive enzymes, bile salts and urea.
4. Dmineral salts, a sugar such as sucrose, and vitamins.

Tap to enlarge

1. Arose steadily from about 50 per cent to reach a maximum at 0,5 and then levelled off for the rest of the range.
2. Bremained close to 73 per cent until 1,0 and then fell abruptly to zero.
3. Cwas unaffected by the concentration of B at any point on the range tested.
4. Dfell sharply to about 50 per cent, held near that value up to 0,5, then declined steadily to zero at 1,75.

Tap to enlarge

1. Araised the concentration of B at which shooting finally ceased altogether.
2. Babolished the effect of regulator B entirely, so that the percentage stayed constant throughout.
3. Cheld a greater percentage of explants shooting between 0,25 and 1,0 of B, so A partly offsets the suppression by B.
4. Dlowered the percentage of explants that formed shoots at every one of the concentrations of B that were tested.

1. Ahaploid, so they can be fertilised to produce a new individual.
2. Bpolyploid, so they carry several times more genetic information than the cells of the parent plant.
3. Ctotipotent, so a single cell retains the ability to give rise to every kind of cell in the plant.
4. Ddiploid, so they carry two copies of every gene in the plant.

Answer this when you sit the paper.

1. Ahas a simple stomach and cannot rely on rumen microorganisms to make the amino acids it needs.
2. Bobtains all of its energy from protein rather than from carbohydrate.
3. Cchews the cud, so its protein is broken down twice before absorption.
4. Dgrows so slowly that its requirement for protein is spread thinly over a very long period of time.

Answer this when you sit the paper.

1. Aage, weight and purpose of the pigs and the nutrient composition of the available feeds.
2. Bbreed of the boar that sired the pigs and the date on which each one of them was weaned.
3. Cmarket price of pork and the distance to the nearest abattoir.
4. Dtemperature and rainfall recorded at the farm in the previous season.

1. Aproduces milk with a higher fat content for the newborn piglets.
2. Bcarries a lighter parasite burden and does not pass worms to her piglets.
3. Ceats less feed during the final weeks of her pregnancy.
4. Dgives birth to a smaller litter that she can suckle more easily.

1. Awill lose enough weight to reduce the size of the piglets.
2. Bcan be starved for several days beforehand so that the birth itself is made easier.
3. Ccan be mated again before the litter she is carrying is born.
4. Dsettles into the clean disinfected pen and is not stressed while giving birth.

1. Aneeds less capital for housing, and the pigs forage part of their own feed.
2. Bproduces pigs of a more uniform weight and finish for the market.
3. Callows a much larger number of pigs to be kept on the same area of land.
4. Dgives faster liveweight gain because the ration can be controlled very exactly.

1. Asome religious and cultural groups do not eat pork, which limits the local market.
2. Bpigs are the only livestock that cannot be sold at auction.
3. Cpigs require a licence issued to one farmer in each district.
4. Dpork is more expensive to transport to the market than any other kind of meat.

1. Acool temperate regions with a long cold winter.
2. Birrigated desert regions where all of the water used is supplied artificially.
3. Cthe humid tropical lowlands of west and central Africa, often on poor soils.
4. Dthe high latitude grasslands of North America and Eurasia.

1. Aa monsoon climate in which the fields are flooded for much of the season.
2. Bhigh temperatures and heavy rain throughout the growing period.
3. Cno rainfall at all, so the crop depends entirely on stored soil water.
4. Da cool moist growing season followed by warm dry weather at harvest.

Answer this when you sit the paper.

1. Aopen ditches, and buried perforated pipes or mole channels laid to a gradient.
2. Ba series of level terraces cut across the slope to hold water on it.
3. Cshallow furrows dug along the contour so that water collects in them.
4. Da bank of soil built around the field to hold rainwater within it.

Answer this when you sit the paper.

1. Araises the pH, supplies calcium, flocculates the clay into crumbs and reduces the toxicity of aluminium.
2. Badds nitrogen and phosphorus directly to the soil in soluble form.
3. Ccoats the particles of the soil so that water can no longer drain away from around the roots of the crop.
4. Dkills the soil bacteria and fungi that produce acid as they respire.

1. Asupplies nutrients in a form that no soil organism has to act on first.
2. Bcan be applied at an exactly known rate of each nutrient per hectare.
3. Creleases all of its nutrients within hours of application, so that the crop responds to it at once.
4. Dsupplies nutrients slowly and adds organic matter that improves soil structure and water holding.

1. Asupplies nitrogen but no other plant nutrient at all.
2. Bcannot be used on any crop that is being grown for human consumption.
3. Cis bulky, variable in composition and may introduce weed seeds.
4. Dmakes the soil more acid every time it is applied.

1. Aabandoning irrigation so that all crops depend on the natural rainfall.
2. Bexpanding irrigation, using improved seed, and cutting losses after harvest through better storage.
3. Cgrowing a single crop across the whole region to simplify marketing.
4. Dreducing the extension services so that farmers are left to make their own decisions unaided.