AQA GCSE Biology

Decomposition

AQA GCSE Biology revision on Decomposition. Aligned to the AQA GCSE Biology 8461 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Which biological role do detritivores perform in the process of natural decomposition?

    • A) They respire glucose
    • B) They digest proteins
    • C) They break down matter
    • D) They absorb nutrients
    Show answer

    Answer: They break down matter

    Detritivores, such as earthworms or woodlice, consume dead organic material and break it into smaller pieces. This increases the surface area available for microorganisms like bacteria and fungi to carry out chemical decomposition.

  2. Question 2

    Why does the rate of decay decrease when the temperature falls below the optimum for decomposer enzymes?

    • A) Enzymes become denatured
    • B) Kinetic energy is reduced
    • C) Substrates are exhausted
    • D) Bacteria stop reproducing
    Show answer

    Answer: Kinetic energy is reduced

    At low temperatures, enzymes and substrates move more slowly, resulting in fewer effective collisions per second. Unlike high temperatures which denature proteins, low temperatures simply slow the metabolic rate of the decomposers.

  3. Question 3

    What is the primary waste product released during the aerobic respiration of decomposers?

    Show answer

    Answer: carbon dioxide

    When decomposers respire aerobically, they break down complex carbon-based molecules like glucose. Carbon dioxide is released as a waste gas, returning carbon to the atmosphere for use by producers in photosynthesis.

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