Biology 0610 | Paper 2 Mock 01 | Multiple Choice (Extended)

An egg cell is large because its cytoplasm contains food (energy) stores of fats and proteins that nourish the embryo during its first days before it can obtain nutrients from the mother. It is not larger because it carries more chromosomes (a gamete carries a half set), needs to swim, or has many mitochondria for movement; those describe the sperm's job, whereas the egg is a supply store.

If the plant produces its own insect-killing protein, pests that feed on it are killed by the crop itself, so there is less need to spray chemical insecticides, saving money and reducing chemical use. The other options describe things this modification does not do: the crop still needs light for photosynthesis, still has to be harvested to be useful, and still needs water to grow. The benefit follows directly from the engineered trait, built-in pest protection.

A benefit to the farmer is something that helps their crop or harvest. The table's benefit entry is that weeds can be killed without harming the crop: a herbicide-resistant crop lets the field be sprayed so the weeds die while the crop survives. The entry that the gene may spread to nearby weeds is listed as a concern, not a benefit, and a poisoned soil or fewer crops would be harms, not advantages.

Each stoma is bordered by a pair of guard cells, and it is these cells that open and close the pore by changing shape as they gain or lose water. On a dry afternoon the guard cells lose water, become flaccid, and close the stoma to conserve water. Palisade cells carry out photosynthesis, root hair cells absorb water from soil, and xylem vessels transport water; none of these control the opening and closing of the stoma.

Alcohol is a depressant, so it slows the activity of the nervous system and lengthens the time taken to respond to a hazard, which is why the driver takes much longer to brake. It does not speed up the nervous system, sharpen sight, or increase muscle strength; the slower response comes from its depressant effect slowing nerve impulse transmission.

The table shows carbon dioxide in exhaled air rising from 4% to 6% after exercise. During exercise the muscles respire faster, and aerobic respiration releases carbon dioxide, so more carbon dioxide is produced and breathed out. Reduced respiration would lower carbon dioxide, photosynthesis does not occur in the lungs, and the oxygen level of the air is not what causes this rise, so increased respiration in the muscles is the cause.

Ion uptake is high with oxygen (20 units) but very low without it (3 units), showing that uptake needs energy from respiration, which needs oxygen. Aerobic respiration supplies the energy for active transport, so removing oxygen starves the process of energy. Ions do not move only by osmosis, cells do not absorb more without oxygen, and oxygen clearly does affect uptake, so the other statements contradict the readings.

The bases of a gene are read in triplets, and each triplet codes for one amino acid. The section shown contains three triplets (CAT, GGA and TTC), so it codes for 3 amino acids. Counting the triplets, not the individual bases, gives the number of amino acids; the nine individual bases here make up exactly three triplets, so the answer is three amino acids.

When the solution around a cell is more concentrated than the cell contents, it has a lower water potential, so water moves out of the cell by osmosis, down the water potential gradient. Osmosis is passive and happens without warming, and movement is a net flow in one direction (outwards here), not equal in both directions, because there is a water potential difference between the cell and its surroundings.

The order in which amino acids are joined to build a protein is set by the sequence of bases in the gene. The base sequence acts as a code, with each triplet of bases specifying one amino acid, so the order of bases dictates the order of amino acids and therefore the protein's shape and function. The amount of water, the temperature of the cytoplasm or the number of chromosomes does not determine the amino acid order; only the base sequence in the gene does.

Light causes the guard cells to open the stomata, so more vapour can diffuse out and transpiration speeds up. The table shows the bubble moving furthest in bright light (11 mm) compared with dim light (6 mm) and darkness (2 mm), confirming that transpiration is fastest in bright light. In darkness the stomata tend to close, which is why the rate there is lowest.

Carbon dioxide is a raw material for photosynthesis and is often the factor limiting the rate, because it makes up only a small fraction of the air. Adding more carbon dioxide removes that limit, so the plants photosynthesise faster, make more food and grow better; this is the grower's aim. It is not done to reduce water loss, kill pests or warm the soil. The point of enriching the air with carbon dioxide is to increase the rate of photosynthesis.

A long body made of many similar segments with legs on nearly every segment describes a myriapod, the group that includes centipedes and millipedes. Insects have just three body parts and three pairs of legs, arachnids have two body parts and four pairs of legs, and crustaceans have two pairs of antennae and are mostly aquatic, so none of these matches a many-segmented, many-legged body. The repeating leg-bearing segments are the giveaway for a myriapod.

The pupil reflex adjusts the amount of light entering the eye to suit the brightness. Moving into a dim corridor means less light is available, so the iris widens the pupil to allow more light to enter and reach the retina, helping you see in the low light. Widening the pupil is not about focusing on near objects (that is the job of the lens) or protecting the lens; it is about controlling light reaching the light-sensitive retina, and in dim conditions the aim is to let more in, not less.

Respiration is the set of chemical reactions in cells that break down nutrient molecules and release energy for the organism's other processes, so it matters because it releases energy from nutrient molecules. It does not detect light or sound (that is sensitivity) and it breaks molecules down rather than building them up. Although carbon dioxide is later removed from the blood, that removal is excretion, not the purpose of respiration itself.

To find which animal is affected, follow the "feeds on" column. The table shows the fox feeding on rabbits, so if a disease wiped out all the rabbits the fox would lose its food source and its numbers might fall. The grass and the oak tree are producers that make their own food, so losing rabbits does not remove their food; the caterpillar feeds on oak leaves, not rabbits, so it is unaffected too. Only the predator that actually eats the lost species suffers directly, so trace the feeding links before deciding.

The task is to find the wrongly classified row. ABO blood group falls into distinct categories (A, B, AB, O) with no intermediates, so it is discontinuous variation, but the row labels it continuous, making that row incorrect. The other rows are right: seed mass and hand span vary smoothly (continuous), and tongue rolling is either/or (discontinuous). So the blood-group row is the mistaken classification.

Excretion is the removal of the waste products of metabolism, the toxic substances made by the chemical reactions inside an organism's cells, such as carbon dioxide from respiration or urea. Getting rid of these self-made waste products is exactly what is described. It is not nutrition, which is the taking in of materials, and it is not reproduction or sensitivity, which do not involve removing waste. Keep excretion separate from egestion, which is the removal of undigested food that never took part in the cells' chemistry.

Two processes are described. Nutrition is the taking in of food materials, which the organism does first; respiration is the chemical breakdown of those nutrient molecules in cells to release energy, which is then used to keep warm. So the pair is nutrition and respiration. It is not movement or excretion (removing waste), nor sensitivity or reproduction, and note that using the released energy for warmth is a use of respiration, not a separate life process here.

Definitions must match the real meaning of each term. The correct row defines genetic engineering as changing an organism's genes by inserting or removing them, which is exactly the note's definition of genetic modification. Breeding the tallest plants together is selective breeding, not genetic engineering. The other wrong rows swap the vocabulary: a plasmid is a loop of DNA (not an enzyme that cuts DNA), and ligase is the joining enzyme (not a loop of DNA).

In bright light the pupil narrows to protect the retina, so the correct stimulus-and-response pairing is bright light with the pupil becoming narrower, which is Row C. Rows that pair bright light with a wider pupil, or dim light with a narrower pupil, get the response the wrong way round, since dim light actually widens the pupil to let more light in.

An insect-pollinated flower usually has brightly coloured, scented petals (often with nectar) to attract the insects that carry its pollen. Small dull green petals, no petals, or large feathery stigmas hanging outside are wind-pollination features. Insects are attracted by colour and scent.

Roots and shoots respond to gravity in opposite ways. A root grows downwards, towards gravity, so it is positively gravitropic (this anchors the plant and reaches water). A shoot grows upwards, away from gravity, so it is negatively gravitropic (this lifts leaves towards light). So the root is positive and the shoot is negative gravitropic; saying both respond the same way misses this opposite behaviour.

Useful protein is only obtained when the bacteria multiply and switch the gene on. The correct row describes a bacterium that reproduces rapidly so the gene is expressed and protein is made in bulk: rapid division copies the recombinant plasmid into millions of cells, each reading the gene to build the protein. Rows describing slow or absent division give no protein, and a bacterium that loses the plasmid loses the gene entirely, so it cannot make protein in bulk.

A gene can exist in more than one version, and each different version is called an allele. Here the seed-colour gene has a green version and a yellow version, so each of these is an allele of that gene. An allele is not the same as a gamete (a sex cell), a chromosome (the whole DNA thread that carries many genes) or a phenotype (the observable feature the allele helps produce).

Reacting quickly to danger is the fight-or-flight response, produced by the adrenal gland and adrenaline, which raises heart rate to ready the body fast. The pancreas with insulin lowers glucose after a meal, the pancreas with glucagon raises glucose during fasting, and the ovary with oestrogen controls puberty, so those gland-hormone pairs handle slower, longer-term changes rather than a rapid emergency response.

Excretion is the removal of the waste products of metabolism, the substances made by the chemical reactions inside cells. Carbon dioxide from respiration and urea from breaking down proteins are both such wastes, so removing them through the lungs and kidneys is excretion. It is not egestion, which removes undigested food that never entered the cells, and it is not movement or nutrition. Remember that excretion deals with waste the body itself made, not with food passing through the gut.

In the table the enzymes cut and join the gene, which leaves the plasmid to do the transport job. The plasmid acts as a vector that carries the gene into the bacterium: it is a small loop of DNA that takes up the gene and is then absorbed by the bacterial cell. Cutting DNA is the restriction enzyme's role, not the plasmid's, and a plasmid neither kills its host nor makes insulin by itself, since the gene it carries is what codes for the protein.

Respiration A uses oxygen and releases a large amount of energy, giving carbon dioxide and water, which are the features of aerobic respiration. Respiration B, using no oxygen, releasing little energy and producing lactic acid, is anaerobic respiration. Combustion is burning (not respiration in cells) and photosynthesis makes food using light rather than releasing energy from it, so neither fits. The use of oxygen with products of carbon dioxide and water identifies aerobic respiration.

A living organism must carry out all seven life processes (movement, respiration, sensitivity, growth, reproduction, excretion, nutrition) and be built from cells. A car can move and can release waste gases, so saying it cannot move or never gives out waste is simply false, and it clearly does need energy from its fuel. What a car cannot do is build new living cells to grow, or make copies of itself, so the feature that keeps it non-living is its inability to reproduce or grow by itself.

Reproduction is the process that makes more of the same kind of organism, so its importance to a species is that it produces new individuals of the same kind, allowing the species to continue. It does not provide energy for movement (that is respiration), control body temperature, or remove waste (that is excretion). Focus on the definition: reproduction is about making new organisms of the same type.

Two life processes are shown together here. Sensitivity is detecting and responding to a stimulus, and the earthworm detects the bright light; movement is an action causing a change of position, and the worm pulls itself away. So the correct pairing is movement and sensitivity. It is not growth or reproduction, which concern increasing in mass and making new organisms, nor excretion, nutrition, respiration or egestion, none of which is happening in this quick escape.

Higher yields, reduced pesticide use, and insect resistance are all benefits of GM crops, so the odd one out is the drawback. The disadvantage is that genes may pass to wild plants, the environmental risk that a modified gene could escape into wild relatives. The other three statements are all advantages, so they cannot be the disadvantage being asked for.

Typical mammal features include a body covered in hair, feeding the young on milk, and a constant (warm) body temperature. Only Organism 1 shows all three. The others fail at least one: feathers point to a bird, and scales or moist skin with a varying body temperature point to a reptile or amphibian. Check that every listed mammal feature is present, not just one.

The table shows that FSH and LH are made by the pituitary gland, while oestrogen and progesterone are made by the ovary. So the pair secreted by the pituitary rather than the ovary is FSH and LH. Any pairing that includes oestrogen or progesterone is wrong, because those two come from the ovary. Keep the two pituitary hormones (FSH and LH) separate from the two ovarian hormones (oestrogen and progesterone).

Bacteria grow abundantly with no antibiotic, but when the antibiotic is added only a few survive and then multiply into a resistant population, this is evolution by natural selection. The antibiotic is a selection pressure from the environment: it kills susceptible cells and leaves the few that already carried resistance to reproduce, so the population becomes resistant across generations. No human is choosing which cells breed, so it is not selective breeding or deliberate cloning. Continuous variation only describes how a feature ranges smoothly across individuals; it does not name this survival-and-reproduction process that the table illustrates.

Burning coal releases sulfur dioxide, which dissolves in rain water to form an acid, producing acid rain that damages trees and lakes far downwind. Carbon dioxide and methane are greenhouse gases rather than the main cause of acid rain, and carbon monoxide is a toxic gas that binds to haemoglobin; the gas responsible for acid rain here is sulfur dioxide.

Protein digestion begins in the stomach, where the enzyme protease works in the acidic conditions created by hydrochloric acid. Each enzyme has an optimum pH, and the stomach protease is shaped to work best in acid. Amylase and maltase act on carbohydrates, not protein, and lipase acts on fat; and protein is not digested in alkaline or neutral conditions in the stomach. So protein digestion in the stomach involves protease working in acidic conditions.

Dividing cells are common in a growing root tip because mitosis is producing new cells for growth. Growth means increasing the number of cells, and mitosis makes genetically identical cells to do this, which is why a rapidly growing region has many cells in division. The cells are not losing chromosomes, and meiosis (which makes gametes such as pollen) does not happen in a growing root tip. Link a region of rapid growth to mitosis making new cells.

Each mitotic division doubles the number of cells: 1 becomes 2, 2 becomes 4, and 4 becomes 8 after the third hour, following the doubling pattern in the table. This is repeated mitosis, where every cell divides into two, so the number follows \(1 \rightarrow 2 \rightarrow 4 \rightarrow 8\), a doubling each hour. After 3 hours there are 8 cells.