A gardener notices that fruit left on the ground in summer rots much faster than fruit stored in a cold cellar over winter. Explain why the rate of decomposition is faster in summer than in winter.

OCR A-Level Biology B — Advancing Biology (H422) — 4.2 Respiration · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Decomposers such as bacteria and fungi break down dead and decaying matter. The rate of decomposition is influenced by temperature, water availability and oxygen availability.

Model answer (5 marks)

Decomposers such as bacteria and fungi carry out the decomposition of the dead fruit.
Higher temperature in summer compared with winter.
Higher temperature increases the rate of decomposition.
Decomposers are more active and reproduce more rapidly at higher temperatures.
In the cold cellar, at lower temperatures, the activity of decomposers is reduced, so decomposition is slower.

Examiner tips

  • Use the exact terminology: decomposers, temperature, activity, reproduction. Show the causal chain: temperature → activity → rate of decomposition. Include both summer and winter comparisons. Keep the answer concise, 5 points total.

Common mistakes

  • Confusing decomposition with photosynthesis. Omitting the role of decomposers. Using vague terms like "hot" instead of "higher temperature”.

Mark scheme (5 marks)

  1. Decomposers / microorganisms carry out decomposition of the dead fruit
  2. Higher temperature in summer compared to winter
  3. Higher temperature increases the rate of decomposition
  4. Decomposers are more active / reproduce more rapidly at higher temperatures
  5. In the cold cellar / at lower temperatures, the activity of decomposers is reduced, so decomposition is slower

Key terms in this question

decomposition · rate of decomposition

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