AQA GCSE Combined Science: Trilogy — Biology Paper 2 (Foundation Tier)

Total marks: 70 · Duration: 75 minutes · Tier: Foundation

Instructions to candidates

Answer all questions in the spaces provided.
You are expected to use a calculator where appropriate.
This paper covers Topics 5–7: Homeostasis and Response, Inheritance, Variation and Evolution, and Ecology.
The maximum mark for this paper is 70. The marks for each question are shown in brackets.

Paper

Section A — Multiple Choice (5 marks)

For each question, choose the one correct answer.

1. Which part of the body controls reactions and coordinates responses? (1 mark) A) Liver B) Central nervous system C) Kidney D) Skin

2. Which hormone controls blood glucose concentration? (1 mark) A) Oestrogen B) Testosterone C) Insulin D) Adrenaline

3. What is the name for a feature passed from parents to offspring through genes? (1 mark) A) Adaptation B) Inherited characteristic C) Habitat D) Competition

4. Which gas is released into the atmosphere during respiration? (1 mark) A) Oxygen B) Nitrogen C) Carbon dioxide D) Hydrogen

5. What is biodiversity? (1 mark) A) The number of animals only B) The variety of all living things in an area C) The size of a habitat D) The amount of water in an ecosystem

Section B — Structured Questions (65 marks)

6. The nervous system allows humans to react to their surroundings. (a) Put the parts of a reflex arc in the correct order. (2 marks) effector · receptor · sensory neurone · motor neurone · relay neurone (b) Explain why a reflex action is described as automatic. (2 marks) (c) Name the gap between two neurones. (1 mark) (d) Describe how an electrical impulse passes across this gap. (3 marks)

7. The body keeps internal conditions constant. This is called homeostasis. (a) What is meant by homeostasis? (1 mark) (b) After a meal, blood glucose rises. Describe how insulin returns it to normal. (3 marks) (c) Name the organ that releases insulin. (1 mark) (d) People with Type 1 diabetes cannot make insulin. State one way Type 1 diabetes is treated. (1 mark)

8. Organisms reproduce to produce offspring. (a) State one difference between sexual and asexual reproduction. (2 marks) (b) Name the type of cell division that produces gametes. (1 mark) (c) In humans, the sex chromosomes are X and Y. A male is XY and a female is XX. Use a genetic cross diagram to show why there is a 50% chance of a baby being a girl. (3 marks)

9. Genes carry information. (a) Name the molecule that genes are made from. (1 mark) (b) Where in the cell are the chromosomes found? (1 mark) (c) A gene for fur colour has a dominant allele B (black) and a recessive allele b (brown). A cross between Bb and Bb is carried out. Complete a Punnett square and give the ratio of black to brown offspring. (4 marks)

10. Living things have changed over time by evolution. (a) State the theory of evolution by natural selection in your own words. (2 marks) (b) Bacteria can become resistant to antibiotics. Explain how a resistant population develops. (4 marks) (c) Give one reason why some species become extinct. (1 mark)

11. Ecosystems depend on the transfer of energy and materials. (a) In a food chain, where does the energy originally come from? (1 mark) (b) Name two things plants compete for. (2 marks) (c) Describe how carbon is returned to the atmosphere as carbon dioxide. (2 marks) (d) A student counted dandelions using a 1 m² quadrat. Explain why they should take several readings and find a mean. (2 marks)

12. Humans affect biodiversity. (a) Give two human activities that reduce biodiversity. (2 marks) (b) Give one way that biodiversity can be protected. (1 mark)

13. This question is about the effect of exercise. A student investigated how exercise affects heart rate. Describe how the body responds to exercise, and explain why these changes happen. In your answer include what happens to heart rate and breathing, and why the muscles need more blood. (6 marks)

14. Organisms live together in ecosystems. (a) Define the term community. (1 mark) (b) Name two abiotic factors that affect organisms. (2 marks) (c) A student used a 0.25 m² quadrat and found a mean of 8 daisies per quadrat. Estimate the number of daisies in a field of area 200 m². (3 marks) (d) Describe how the student should place the quadrats to get a representative sample. (2 marks) (e) Explain how a polar bear is adapted to reduce heat loss. (3 marks) (f) Describe the role of decomposers in recycling carbon. (2 marks) (g) Give two human activities that reduce biodiversity. (2 marks) (h) Give one way biodiversity can be protected. (1 mark)

Mark Scheme

1. B 2. C 3. B 4. C 5. B [5 × 1 = 5]

6. (a) receptor → sensory neurone → relay neurone → motor neurone → effector B2 (B1 if one error) [2] (b) it does not involve the conscious brain (1); so it is fast / protects the body (1) B1 B1 (c) synapse B1 (d) a chemical (neurotransmitter) is released (1); it diffuses across the gap (1); and triggers an impulse in the next neurone (1) B1 B1 B1 [9]

7. (a) keeping a constant internal environment B1 (b) insulin is released (1); causes glucose to move into cells / liver (1); stored as glycogen (1) B1 B1 B1 (c) pancreas B1 (d) insulin injections B1 [6]

8. (a) sexual uses two parents/gametes and gives variation; asexual uses one parent and gives identical offspring B1 B1 (b) meiosis B1 (c) cross XX × XY; offspring XX, XX, XY, XY (Punnett) (1); 2 XX : 2 XY (1); = 50% girls (1) B1 B1 B1 [6]

9. (a) DNA B1 (b) in the nucleus B1 (c) Punnett with parents Bb × Bb → BB, Bb, Bb, bb M1 (gametes correct) A1 (offspring correct); 3 black : 1 brown B1; phenotype reasoning B1 [6]

10. (a) organisms with characteristics best suited to the environment (1) survive and reproduce, passing on their genes (1) B1 B1 (b) variation exists in the bacteria (1); some have a resistance mutation (1); these survive the antibiotic and reproduce (1); resistance is passed on so the population becomes resistant (1) B1 B1 B1 B1 (c) any one: new disease, habitat destruction, new predator, climate change B1 [7]

11. (a) the Sun / light B1 (b) any two: light, water, space, mineral ions B1 B1 (c) respiration of organisms (1); and combustion/burning of fuels or decay (1) B1 B1 (d) results vary / to get a reliable (representative) estimate (1); reduces the effect of anomalies (1) B1 B1 [7]

12. (a) any two: deforestation, pollution, burning fossil fuels, building/farming B1 B1 (b) any one: nature reserves, breeding programmes, replanting trees, reducing deforestation B1 [3]

13. Levels-marked, 6 marks. Indicative content: heart rate increases and breathing rate/depth increases; this delivers more oxygen and glucose to muscles and removes carbon dioxide faster; muscles respire more during exercise so need more energy; if oxygen is insufficient, anaerobic respiration produces lactic acid.

Level 3 (5–6): changes described and clearly explained in terms of supplying oxygen/glucose and removing CO₂.

Level 2 (3–4): changes described with some explanation.

Level 1 (1–2): isolated relevant points.

0: nothing relevant. [6]

14. (a) all the populations of different species in an area B1 (b) any two: temperature, light, water, pH, oxygen B1 B1 (c) density = 8 ÷ 0.25 = 32 per m² M1; × 200 M1; = 6400 daisies A1 (d) place quadrats at random (1); e.g. using random coordinates / repeat across the field (1) B1 B1 (e) thick fur/fat for insulation (1); small surface-area-to-volume ratio (1); reduces heat loss (1) B1 B1 B1 (f) break down dead matter (1); releasing CO₂ (by respiration) back to the air (1) B1 B1 (g) any two: deforestation, pollution, fossil-fuel burning, building B1 B1 (h) any one: reserves, breeding programmes, replanting B1 [16]

AQA GCSE Combined Science (Trilogy) — Biology Paper 2 (Foundation Tier)