Mark Scheme

Section A: 1. B; 2. A; 3. C; 4. D; 5. C. (5)

6 (a) Regulation of internal conditions (1) to maintain optimum conditions for function, in response to internal and external change (1). (b) receptors; coordination centres; effectors (3). (c) pancreas detects high glucose / releases insulin (1); insulin makes cells (liver/muscle) take up glucose (1); excess stored as glycogen (1). (8)

7 (a) stimulus → receptor (1) → sensory neurone (1) → relay neurone (CNS) (1) → motor neurone → effector → response (1). (b) impulse triggers release of chemical/neurotransmitter (1); diffuses across the gap (1); starts a new impulse in the next neurone (1). (c) protective / automatic / rapid (1). (8)

8 (a) FSH (1); LH (1). (b) contains oestrogen/progesterone (1) which inhibits FSH so eggs don't mature (1). (c) hormonal: very effective but side effects, no STI protection (2); barrier: protects against STIs, no hormones, but less reliable if misused (2). (8)

9 (a) gametes F and f for each parent (1); offspring FF, Ff, Ff, ff (1). (b) 1 in 4 / 25% (1). (c) genotype = the alleles present (1); phenotype = the characteristic shown (1). (5)

10 (a) variation in a species (1); those best adapted survive (1) and reproduce (1); passing on the beneficial alleles, so the species changes over generations (1). (b) random mutation gives resistance (1); resistant bacteria survive antibiotics (1); they reproduce and pass on the resistance allele (1). (c) any two: fossils; antibiotic resistance; (extinction) (2). (9)

11 (a) population = all the organisms of one species in a habitat (1); community = all the populations of different species (1). (b) place quadrats randomly (1); count daisies in each / find mean per quadrat (1); multiply mean by total area ÷ quadrat area (1). (5)

12 — Levels (6): Indicative: photosynthesis removes CO₂ from the air (carbon into glucose/plants); carbon passes along food chains by feeding; respiration (plants, animals, decomposers) returns CO₂; combustion of fuels/wood returns CO₂; decomposers break down dead organisms.

• L3 (5–6): A full cycle with correctly named processes for both removal and return of carbon.
• L2 (3–4): Several processes named with some links.
• L1 (1–2): Isolated statements.

Sample Answers with Examiner Commentary

Question 12 — Sample Answers

Grade 9 answer "Carbon dioxide is removed from the atmosphere by photosynthesis in plants and algae, which converts the carbon into glucose and other compounds. This carbon then passes along food chains when animals eat plants. Carbon is returned to the air by respiration in plants, animals and microorganisms, and by the combustion of wood and fossil fuels. When organisms die, decomposers (microorganisms) break them down and respire, releasing CO₂ back into the atmosphere, so the cycle continues." Mark: 6/6. Examiner commentary: All the key processes are correctly named for both the removal (photosynthesis) and the return (respiration, combustion, decomposition) of carbon, with the feeding link included. Top band.

Grade 6 answer "Plants take in carbon dioxide for photosynthesis. Animals eat plants. When things respire or burn, carbon dioxide goes back into the air." Mark: 4/6. Examiner commentary: Correct on photosynthesis, feeding, respiration and combustion, but does not mention decomposers breaking down dead organisms, which is needed for the top band.

Grade 3 answer "Plants use carbon dioxide and animals breathe it out. Burning things makes carbon dioxide." Mark: 2/6. Examiner commentary: Some credit for photosynthesis and combustion, but "animals breathe it out" should be linked to respiration, and there is no mention of decomposition or the food chain. Use the correct process names to gain marks.

Question 10(a) — Sample Answers

Grade 9 answer "Within a species there is genetic variation. The individuals with characteristics best suited to the environment are more likely to survive and reproduce. They pass on the beneficial alleles to their offspring. Over many generations these advantageous characteristics become more common, so the species evolves." Mark: 4/4. Examiner commentary: All four steps — variation, survival of the best adapted, reproduction, inheritance over generations — are present and in order.

Grade 6 answer "The animals that are best suited survive and have babies. They pass on their genes so the species changes." Mark: 3/4. Examiner commentary: Credit for survival of the best adapted, reproduction and inheritance, but the first step — variation within the species — is not stated, which caps it below full marks.