Explain why aerobic respiration is described as an exothermic reaction and state one use of the energy released during cellular respiration in the human body.

AQA GCSE Biology (8461) — 4.4.2 Respiration · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Aerobic respiration is exothermic because it releases energy to the surroundings when glucose and oxygen are broken down into carbon dioxide and water.

The energy released is used by the human body for muscle contraction during exercise.

Examiner tips

  • Use the word "exothermic" and explain that energy is released to the surroundings. Mention the reactants (glucose and oxygen) and the products. Give a specific example of energy use, such as muscle contraction.
  • common_mistakes
  • :
  • Saying the reaction is endothermic or that energy is absorbed. Failing to identify glucose and oxygen as reactants. Giving an irrelevant use of energy, e.g. photosynthesis.

Mark scheme (4 marks)

  1. Aerobic respiration releases energy (to the surroundings / environment)
  2. This makes it exothermic because exothermic reactions release energy
  3. Glucose (and oxygen) are broken down / reactants are broken down to release energy
  4. One valid use of energy from cellular respiration, e.g. muscle contraction / maintaining body temperature / active transport / building larger molecules

Key terms in this question

aerobic respiration · exothermic reaction · cellular respiration · energy

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