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9.3 Material cycles and decomposition

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Question 15
F

A compost heap is moist and contains enough oxygen. Its temperature rises from 20 ∘C20\,^{\circ}\text{C}20∘C to 35 ∘C35\,^{\circ}\text{C}35∘C, below the optimum temperature of its decomposers. Decomposition then becomes faster. Which explanation is correct?

[1]
A

External heat kills decomposers, so fewer enzymes break down the waste.

B

External heat creates oxygen, so more enzymes break down the waste.

C

Respiration releases heat, and the warmer conditions increase enzyme activity.

D

Respiration releases heat, and the warmer conditions denature all enzymes.

Markscheme

9.3 Material cycles and decomposition Questions

  1. GCSE
  2. /Biology
  3. /9.3 Material cycles and decomposition

44 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.

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