Biology Paper 2 November 2022

1. Asystem, made of several organs working together for one job
2. Btissue, made of many identical cells grouped together
3. Cunit, the smallest part able to carry out the processes of life
4. Dorgan, made of several different tissues working together

1. AThe process by which a specialised cell reverts to its original unspecialised, general purpose form.
2. BThe process by which two different specialised cells fuse together to form one combined cell.
3. CThe process by which a cell divides repeatedly without ever changing its shape or function.
4. DThe process by which an unspecialised cell develops a particular structure and function suited to one job it performs in the organism.

1. ATo absorb water and mineral salts from the surrounding soil.
2. BTo carry out photosynthesis using light absorbed by chloroplasts.
3. CTo store food reserves for the growing embryo.
4. DTo fertilise the ovum (egg cell), carrying the male's genetic material to it.

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1. APhotosynthesis, since it is packed with chloroplasts positioned near the leaf's upper surface to trap light.
2. BSupport, since its thick lignified wall holds the leaf rigid against gravity.
3. CStorage, since its large permanent vacuole is filled with reserve starch grains.
4. DAbsorption, since its extended surface takes up water and mineral salts from the soil.

1. AHydrogen and oxygen atoms, in the ratio 1 hydrogen to 2 oxygen.
2. BCarbon and oxygen atoms, in the ratio 1 carbon to 2 oxygen.
3. CHydrogen and nitrogen atoms, in the ratio 2 hydrogen to 1 nitrogen.
4. DHydrogen and oxygen atoms, in the ratio 2 hydrogen to 1 oxygen.

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1. AA very low boiling point that causes it to evaporate completely at room temperature within minutes.
2. BA strong tendency to form a solid crystal lattice at all normal environmental temperatures.
3. CA complete lack of any attraction between neighbouring water molecules.
4. DA relatively high boiling point and high specific heat capacity, so its temperature changes slowly.

1. AAdhesion, which allows water to stick to the walls of a glass container only.
2. BCohesion, which allows water molecules to stick together, producing surface tension and letting water be pulled up as a continuous column in the xylem.
3. CIonisation, which allows water to dissolve any substance placed into it.
4. DPolarisation, which allows water to conduct an electric current freely.

1. ADiffusion; it makes water molecules spread out evenly through the air inside the tube.
2. BOsmosis; it draws water out of the tube and into the surrounding cells.
3. CAdhesion; it helps water rise up the inside walls of the narrow tube (capillarity).
4. DCohesion; it causes water to be repelled from the tube's walls entirely.

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1. AIt has no biological significance, since both values are close to 1 g/cm3.
2. BWarm water always freezes before cold water because it is less dense.
3. CCold water is denser and sinks below warmer water, so a pond stratifies by temperature; this is also why ice, being less dense still, forms and floats on the surface, insulating the water below so organisms can survive underneath through winter.
4. DCold water is less dense and rises above warmer water, driving warm water to the pond bed.

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1. ACoiling allows the machine to pump the dialysis fluid in the opposite direction to the blood, which has no effect on diffusion.
2. BCoiling shortens the total length of tubing needed, saving on manufacturing material.
3. CCoiling increases the tube's surface area in contact with the dialysis fluid and keeps the blood inside it for longer, increasing the rate and amount of diffusion of waste substances out of the blood.
4. DCoiling slows the blood down so much that it clots inside the tube, which helps prevent infection.

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1. ASo that there is no concentration gradient for the salts the body needs to keep, meaning useful salts are not lost from the blood along with the waste; only substances present in excess, such as urea, still diffuse out.
2. BSo that salt diffuses from the dialysis fluid into the blood, raising the patient's blood salt level above normal.
3. CSo that the dialysis fluid can be reused indefinitely without ever being replaced.
4. DSo that all the salt in the blood, needed or not, diffuses out into the fluid and is removed completely.

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1. AIt detects rotation of the head and sends information used to maintain balance.
2. BIt equalises air pressure between the middle ear and the throat.
3. CIt converts sound vibrations into nerve impulses that travel to the brain.
4. DIt channels sound waves from the pinna to the eardrum, and its wax and fine hairs trap dust and keep the eardrum moist.

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1. AThey convert sound vibrations directly into nerve impulses sent to the brain.
2. BThey amplify sound vibrations before passing them to the cochlea.
3. CThey detect changes in the position and rotation of the head, providing information used to maintain balance.
4. DThey produce wax that lubricates and protects the auditory canal.

1. ASound vibrations are converted into nerve impulses at a faster rate than normal.
2. BSound vibrations are no longer converted into nerve impulses, or fewer impulses are generated, so less sound information reaches the auditory nerve and brain.
3. CThe eardrum stops vibrating in response to sound waves reaching it.
4. DThe semicircular canals take over the cochlea's role and hearing is unaffected.

1. ABecause the hair cells of the cochlea regenerate too slowly to ever fully recover.
2. BBecause the hair cells of the cochlea do not regenerate once they are destroyed, so the loss of hearing they caused cannot reverse itself.
3. CBecause the auditory nerve immediately dies once the cochlea stops sending it impulses.
4. DBecause the eardrum permanently loses its ability to vibrate once the cochlea is damaged.

1. AThey contain chloroplasts and can carry out photosynthesis independently.
2. BThey are visible using a standard light microscope without any special staining.
3. CThey have no cellular structure, consisting only of genetic material surrounded by a protein coat.
4. DThey have a fully formed nucleus enclosed by a nuclear membrane, like other eukaryotic cells.

1. AThey can only reproduce inside a living host cell, being unable to carry out life processes on their own outside one.
2. BThey reproduce exclusively by binary fission, splitting into two identical viruses.
3. CThey are classified as multicellular organisms belonging to the kingdom Animalia.
4. DThey can carry out all life processes independently, without needing a host cell.

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1. ACertain bacteria ferment milk to produce dairy products such as yoghurt and cheese.
2. BCertain bacteria photosynthesise inside chloroplasts to produce most of the world's timber.
3. CCertain bacteria are used to weave cotton fibres directly into cloth.
4. DCertain bacteria convert atmospheric oxygen into carbon dioxide for industrial use.

1. ADecomposer bacteria prevent any organic matter from ever breaking down, preserving it indefinitely.
2. BDecomposer bacteria only exist inside living animals and play no role in the soil.
3. CDecomposer bacteria break down dead organic matter, recycling nutrients back into the soil and improving its fertility for farming.
4. DDecomposer bacteria convert soil minerals directly into new bacterial cell walls, permanently removing them from the soil.

1. ANitrogen fixing bacteria attack the roots of legumes, destroying the plant's ability to take up water.
2. BNitrogen fixing bacteria in the root nodules of legumes make nitrogen available to plants, improving soil fertility and crop yields.
3. CNitrogen fixing bacteria remove all nitrogen compounds from the soil, reducing crop yields wherever they are present.
4. DNitrogen fixing bacteria convert soil nitrogen into oxygen gas, which plants then use for respiration.

1. AGenetically modified bacteria are used in industry to manufacture products such as human insulin and antibiotics.
2. BWild, unmodified bacteria manufacture plastics directly from atmospheric carbon dioxide at industrial scale.
3. CBacteria are used to smelt metal ores into pure metal in the mining industry.
4. DBacteria are used to generate electricity directly by photosynthesis in power stations.

1. AA gene is a pair of alleles found together at the same position on homologous chromosomes.
2. BA gene is a length of a DNA molecule (part of a chromosome) that codes for one particular characteristic.
3. CA gene is one complete chromosome carrying every characteristic of the organism.
4. DA gene is the visible, physical form in which a characteristic appears in an organism.

1. AAn allele is one of two or more alternative forms of a gene, occupying the same position (locus) on homologous chromosomes.
2. BAn allele is the physical location of a chromosome within the nucleus.
3. CAn allele is a chromosome found only in the sex cells of an organism.
4. DAn allele is any length of DNA that does not code for a characteristic.

1. ACodominance is a condition in which both alleles of a gene are expressed together in the phenotype of a heterozygous organism, with neither dominant over the other.
2. BCodominance is a condition in which a gene has only one possible allele in the whole population.
3. CCodominance is a condition in which an organism carries three or more alleles of the same gene at once.
4. DCodominance is a condition in which one allele completely masks the effect of the other allele in a heterozygote.

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1. AA female has two X chromosomes (XX) and a male has one X and one Y chromosome (XY).
2. BA female has one X and one Y chromosome (XY) and a male has two X chromosomes (XX).
3. CBoth females and males have two X chromosomes (XX), with sex determined by a separate gene elsewhere.
4. DA female has two Y chromosomes (YY) and a male has one X and one Y chromosome (XY).

1. AThe offspring's sex is determined by chance at fertilisation and is unrelated to which chromosomes are inherited.
2. BThe father's sperm determines the offspring's sex, always producing males, since every sperm carries a Y chromosome.
3. CThe mother's egg determines the offspring's sex, since only she carries any sex chromosome at all.
4. DThe father's sperm determines the offspring's sex: an X-carrying sperm produces a female (XX) and a Y-carrying sperm produces a male (XY), in roughly equal (1:1) proportions.

1. AIt must be fully opened, so that a large, hot blue flame is produced immediately on lighting.
2. BIt must be closed, so that the gas ignites as a yellow, luminous (safety) flame rather than an invisible, dangerously hot blue flame.
3. CIt must be removed completely from the burner before the gas is turned on.
4. DIt has no effect on the flame produced and may be left in any position.

1. AThe air hole must already be fully open.
2. BThe burner must already be producing a roaring blue flame.
3. CThe rubber tubing must be disconnected from the gas supply.
4. DThe flame from a lit match (or spark lighter) must be held ready at the top of the barrel.

1. AThe gas tap is opened further until the yellow flame simply grows taller, without changing colour.
2. BThe rubber tubing is pinched to slow the gas flow until the flame turns green.
3. CThe air hole is closed further still, deepening the yellow flame for heating.
4. DThe air hole is opened gradually until the flame becomes a small, roaring, blue (non-luminous) flame.

1. AStructural engineer, designing the framework of tall buildings.
2. BGraphic designer, creating visual artwork for advertising.
3. CTax accountant, preparing financial statements for companies.
4. DWildlife/game ranger, working to conserve and manage wild animal populations.

1. AVeterinary doctor, diagnosing and treating diseases and injuries in animals.
2. BCivil engineer, planning and constructing roads and bridges.
3. CReal estate agent, arranging the sale and rental of properties.
4. DFashion designer, creating and producing clothing lines.

1. AThey are unaffected by temperature, since proteins cannot be denatured by heat.
2. BThey are denatured by high temperature, permanently losing their functional shape and activity.
3. CThey become permanently more active the hotter they get, with no upper limit.
4. DThey convert into a different type of molecule entirely once heated.

1. AIt only functions once in the lifetime of the organism that produced it.
2. BIt works equally well at every possible temperature and pH.
3. CIt can catalyse the breakdown or formation of any substrate presented to it.
4. DIt acts on only one particular substrate, or one type of reaction, and no other.

1. AIt is permanently consumed in every reaction it catalyses, so a fresh supply is needed for each reaction.
2. BIt slows down the rate of a reaction, protecting the cell from reacting too quickly.
3. CIt only works outside living cells, never inside them.
4. DIt speeds up the rate of a reaction without being used up or permanently changed itself, so it can be reused.

1. AThe rate of reaction only depends on temperature, never on pH.
2. BThe rate of reaction is at its maximum at the optimum pH, since the active site is exactly the right shape to bind the substrate there.
3. CThe rate of reaction is at its lowest at the optimum pH, and rises steadily the further the pH moves away from it.
4. DThe optimum pH has no measurable effect on the enzyme's rate of reaction.

1. AActivity falls, and at a pH far enough from the optimum the enzyme's active site changes shape so much that it is denatured, permanently losing its activity.
2. BActivity rises steadily without limit as the pH moves away from the optimum.
3. CActivity is restored to maximum the moment the pH returns exactly to 7.
4. DActivity is unaffected until the pH is exactly 7, regardless of the enzyme's own optimum.

1. ASealing all windows in crowded rooms to keep air from escaping.
2. BAvoiding all chest X-rays and sputum testing to reduce clinic costs.
3. CBCG vaccination of infants and other at-risk individuals.
4. DEncouraging infected individuals to stop taking any prescribed antibiotics once symptoms ease.

1. AIt has no effect on the individual patient but reduces costs for the health system.
2. BIt cures the infected person fully and prevents the TB bacteria from developing resistance to the antibiotics, which would happen if the course were stopped early.
3. CIt is only used to treat patients who have already fully recovered from TB.
4. DIt replaces the need for any other TB control method, such as vaccination or improved ventilation.

1. AImproving ventilation in crowded living and working spaces, and educating people to cover their mouth when coughing.
2. BEncouraging people with active TB symptoms to work in crowded, poorly ventilated spaces as usual.
3. CDiscouraging any contact tracing of people who have been near an infected person.
4. DReducing the nutritional quality of food available to at-risk populations.

1. AAlcohol abuse always increases a family's income, since the abuser works longer hours.
2. BAlcohol abuse only affects the abuser's own personal spending, never the wider family budget.
3. CMoney that should go towards food, school fees and healthcare is instead spent on alcohol, lowering the family's standard of living.
4. DAlcohol abuse has no effect on family finances, since alcohol itself is inexpensive.

1. AIt often leads to domestic violence, quarrelling and neglect, which damages relationships between spouses and between parents and children.
2. BIt only affects relationships with people outside the family, such as neighbours or coworkers.
3. CIt strengthens family relationships, since shared struggles bring family members closer together.
4. DIt has no effect on relationships, only on the abuser's own physical health.

1. AThe height of surrounding buildings and the crop's row spacing alone.
2. BLight intensity and carbon dioxide concentration.
3. CSoil colour and the time of day the crop was planted.
4. DWind speed and atmospheric pressure alone.

1. AThe coldest possible temperature always gives the highest rate of photosynthesis.
2. BOnly the temperature of the soil matters; air temperature has no effect on productivity.
3. CA warm temperature speeds up the enzyme controlled reactions of photosynthesis, but too high a temperature denatures the enzymes involved and reduces productivity.
4. DTemperature has no effect at all on the rate of photosynthesis or plant productivity.

1. AFertile soil with adequate mineral nutrients (such as nitrates, phosphates and potassium) and good soil structure allowing healthy root growth.
2. BCompacted, poorly aerated soil that restricts root growth and respiration.
3. CSoil entirely free of any mineral nutrients, so roots do not have to compete for them.
4. DSoil kept permanently waterlogged, regardless of the crop being grown.

1. AThe cells are tightly packed with no air spaces at all, maximising the number of cells per unit volume.
2. BThe cells are arranged in a single dense layer that blocks gas exchange to protect the leaf from water loss.
3. CThe cells are arranged to prevent any contact with the air spaces connected to the stomata.
4. DThe cells are loosely packed, leaving large interconnected air spaces that allow carbon dioxide to diffuse quickly to and from every cell.

1. AThey actively pump carbon dioxide out of the leaf and into the surrounding air.
2. BThey convert light energy directly into nerve impulses within the leaf.
3. CThey are completely waterproof, preventing any water from leaving the leaf.
4. DThey allow water to evaporate into the air spaces, contributing to transpiration, over a large internal surface area created by the loose packing.

1. AIt removes the need for vaccines to ever be produced again.
2. BIt makes it impossible to genetically modify crop plants for improved yields.
3. CIt allows mass production of useful human proteins, such as insulin, using genetically modified bacteria, which is cheaper and safer than extracting them from animals or cadavers.
4. DIt prevents any further research into treating inherited genetic disorders.

1. AIt removes the need for crops to ever be watered or fertilised.
2. BIt makes crops permanently unable to be eaten by any pest or disease.
3. CIt allows crops to be genetically modified to be more productive and resistant to pests, diseases or drought, improving food security.
4. DIt guarantees that every genetically modified crop will fail to grow.

1. ARecombinant DNA technology makes genetic diversity in crops impossible to reduce.
2. BGenetically modified organisms released into the environment could interbreed with wild relatives or outcompete natural species, upsetting ecosystems.
3. CGenetically modified organisms can never survive outside a laboratory, so they pose no environmental risk at all.
4. DRecombinant DNA technology has eliminated all forms of crop disease worldwide.

1. AIt makes all traditional, non-modified crop varieties immediately extinct worldwide.
2. BNew, unforeseen allergens or toxins could be introduced into the food chain, posing risks to human health.
3. CIt guarantees that no genetically modified food product can ever contain an allergen.
4. DIt removes any possibility of pests evolving resistance to modified crops.

1. AThe bacterial plasmid is heated until it denatures, which activates it to accept the human gene automatically.
2. BThe human insulin gene is cut out using a restriction enzyme, a bacterial plasmid is cut open with the same enzyme, and the gene is inserted into the plasmid and joined using DNA ligase.
3. CThe bacterial plasmid is destroyed entirely and replaced with a whole human chromosome.
4. DThe human insulin gene is left inside human cells, and only the bacterial plasmid is altered.

1. AThe recombinant plasmid is destroyed once it has been formed, since only its formation, not its use, produces insulin.
2. BThe recombinant plasmid is inserted into a bacterium, which is allowed to multiply rapidly in large fermenters; as the bacteria multiply and express the inserted gene, they produce human insulin, which is then extracted and purified.
3. CThe recombinant plasmid is injected directly into a diabetic patient's bloodstream, where it produces insulin on its own.
4. DThe recombinant plasmid is placed in a test tube of glucose solution, which alone causes it to produce insulin.

1. AIt removes trees that provide food, shelter and breeding sites for many species, destroying their habitats.
2. BIt has no direct effect on habitats, since animals simply relocate to nearby forested areas without any loss.
3. CIt increases the amount of habitat available to every species equally.
4. DIt only affects species that live underground, leaving all above ground species unaffected.

1. ASmall, isolated populations always grow faster than large populations, so they are never at risk.
2. BIsolation from other populations guarantees a species long term genetic health.
3. CSmall populations are unaffected by disease, since fewer individuals means fewer chances for disease to spread.
4. DSmall, isolated populations are more vulnerable to inbreeding, disease and chance events, and can more easily die out locally, lowering biodiversity.

1. AIt exposes soil to erosion and leaching, lowering soil fertility, and it changes the local climate (e.g. less rainfall, more temperature extremes), making conditions unsuitable for species adapted to the original forest.
2. BIt permanently increases soil fertility everywhere trees are removed.
3. CIt stabilises the local climate, making it more suitable for every species that lived there before.
4. DIt has no effect on soil or climate, only on the trees themselves.

1. AThey have no genetic material of any kind.
2. BTheir DNA is organised into many linear chromosomes, just like a eukaryotic cell.
3. CTheir DNA lies free in the cytoplasm as a single circular loop, not enclosed within a nuclear membrane, so they have no true, membrane bound nucleus.
4. DTheir DNA is enclosed within a fully formed nuclear membrane, exactly like a eukaryotic cell.

1. ABacteria have a cell wall made of cellulose, identical to that of a plant cell.
2. BBacteria are always larger in size than eukaryotic cells.
3. CBacteria lack membrane bound organelles such as mitochondria and chloroplasts, and their cell wall is made of peptidoglycan rather than cellulose or chitin.
4. DBacteria possess every membrane bound organelle found in eukaryotic cells, in identical form.