Biology Paper 2 November 2019

Answer this when you sit the paper.

1. AThey are not used up in the reaction and can be reused
2. BThey only work when present in very large amounts
3. CThey change permanently with each reaction they catalyse
4. DThey react only once and are then destroyed

1. AThe growth response of a plant to light, with shoots bending towards the light source, called phototropism
2. BThe growth response of a plant to touch, such as a tendril curling around a support, called thigmotropism
3. CThe growth response of a plant to gravity, with roots growing downwards and shoots growing upwards
4. DThe growth response of a plant to water, with roots growing towards moist soil, called hydrotropism

1. AAuxin accumulates on the lower side of the root, causing that side to elongate faster, so the root curves upward, against gravity
2. BAuxin accumulates on the lower side of the shoot, not the root, causing that side to elongate faster, so the shoot curves downward towards gravity; this describes shoot behaviour, not a root's response
3. CAuxin is evenly distributed on both sides of the root, so both sides elongate at the same rate and the root does not curve
4. DAuxin accumulates on the upper side of the root, causing that side to elongate faster than the lower side, so the root curves downward

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Answer this when you sit the paper.

1. AThe ovum is diploid, while the palisade cell is haploid
2. BThe ovum is specialised for photosynthesis, while the palisade cell is specialised for fertilization
3. CThe ovum has no cell wall, while the palisade cell has a cell wall
4. DThe ovum has chloroplasts, while the palisade cell does not

Answer this when you sit the paper.

1. ADrinking untreated water directly from rivers, which increases exposure to the cercariae that cause infection
2. BAvoiding swimming or bathing in untreated rivers or dams, and eliminating water snails
3. CEncouraging urination and defecation in water bodies, which spreads the parasite's eggs into the water
4. DAvoiding all forms of medical treatment for infected people, which allows the infection to persist and spread

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Answer this when you sit the paper.

1. AThey lack cellular structure and their own metabolism, only replicating inside host cells
2. BThey have a cellulose cell wall unlike any known kingdom, though viruses have no cell wall or cellular structure
3. CThey can survive independently and reproduce without a host, though viruses can only replicate inside a host cell
4. DThey are too large to be classified by scientists, though viruses are in fact far smaller than bacteria

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Answer this when you sit the paper.

1. AIncreasing the slope gradient of the site
2. BDiverting all rainwater directly onto the exposed soil
3. CAfforestation and gulley reclamation
4. DRemoving all vegetation to expose bare soil

1. AA plant cell has an irregular shape; an animal cell has a regular shape
2. BA plant cell has a cellulose cell wall; an animal cell does not
3. CA plant cell has a central nucleus; an animal cell has a peripheral nucleus
4. DA plant cell stores food as glycogen; an animal cell stores food as starch

1. AIt has numerous mitochondria to produce energy, and a flagellum, for swimming to the ovum
2. BIt has a cellulose cell wall to protect it during fertilization, though sperm, like other animal cells, have no cell wall
3. CIt has chloroplasts to produce its own energy by photosynthesis, though chloroplasts occur in plant cells, not sperm
4. DIt has a large permanent vacuole to store food for the journey, a feature of plant cells, not sperm cells

1. AIt maintains desirable characteristics in all plants and allows rapid growth to meet market demand
2. BIt prevents the gardener from producing more than one crop per season, though it allows rapid, repeated multiplication
3. CIt introduces new genetic variation into every crop, though vegetative propagation produces genetically identical clones
4. DIt slows down the growth of new plants, saving on fertiliser, though it is valued for producing plants faster than seeds

1. AThey are a source of food, medicine, fuel and raw materials such as timber
2. BSupplying most of the world's drinking water directly, more than rainfall or groundwater do
3. CMaking livestock farming unnecessary, since crops alone can replace meat, milk and hides
4. DProviding the majority of agricultural jobs, more than processing, trade or forestry combined

1. AProduction of insulin to regulate blood sugar, a role carried out by the pancreas, not the liver
2. BFiltration of blood to form urine, a role carried out by the kidney, not the liver
3. CProduction of red blood cells in an adult, a role carried out by bone marrow, not the liver
4. DProduction of bile, deamination of excess amino acids, and production of urea

1. ACarbohydrates are no longer absorbed in the small intestine, though carbohydrate digestion depends on amylase, not bile
2. BFats are digested faster, as bile is no longer needed, though bile is essential for emulsifying fat first
3. CFats are not emulsified, slowing lipid digestion by the enzyme lipase
4. DProteins are no longer digested in the stomach, though protein digestion depends on pepsin, not bile

1. AThe enzyme protease
2. BThe enzyme lipase
3. CThe enzyme amylase
4. DThe enzyme ligase

1. ADoing away with medical treatment altogether, when recombinant DNA products such as insulin are themselves medical treatments
2. BRidding the world of every crop disease, an outcome no single biotechnology technique can promise
3. CEnding the need for farmers to grow crops, though crops are still grown and merely made more productive
4. DProduction of medicines such as insulin, and crops with improved yields

1. AIt follows a random distribution rather than a normal distribution, when it in fact follows a normal distribution
2. BIt shows no clear-cut differences between individuals and is influenced by both genes and environment
3. CIt shows distinct, qualitative differences with no intermediates, which instead describes discontinuous variation
4. DIt is influenced by genes only, not environment, when continuous variation is influenced by both

Answer this when you sit the paper.

1. ADenitrifying bacteria, which instead convert nitrates back into atmospheric nitrogen
2. BNitrogen-fixing bacteria
3. CNitrifying bacteria, which convert ammonia into nitrates, not atmospheric nitrogen
4. DAmmonifying bacteria, which convert dead organic matter into ammonia, not atmospheric nitrogen

1. AIt has higher recycling of nutrients, a feature more typical of undisturbed natural ecosystems
2. BIt is generally more stable than a natural ecosystem, when it is in fact usually less stable
3. CIt has no human influence and higher biodiversity, when an artificial ecosystem is shaped by humans
4. DIt has lower biodiversity and organisms are more susceptible to pests and diseases