Explain why cellular respiration is described as both 'universal' and 'exothermic'.

OCR GCSE Biology A: Gateway Science (J247) — B1.2 What happens in cells (and what do cells need) · Explain · 4 marks · View as Markdown

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

A student is studying what happens inside living cells. They read that cellular respiration is a continuously occurring chemical process found in all living organisms, and that it releases energy from the breakdown of organic compounds such as glucose.

Model answer (4 marks)

Cellular respiration is described as universal because it occurs in all living cells, and it is a continuously occurring process that never stops in living cells.
It is described as exothermic because it releases energy, which is stored in the form of ATP produced from the breakdown of organic compounds such as glucose.

Examiner tips

  • Use the exact words 'universal' and 'exothermic' as in the mark scheme.
  • Show that respiration occurs in all cells and is continuous. Explain that energy is released as ATP from glucose breakdown.

Common mistakes

  • Confusing cellular respiration with photosynthesis. Mentioning only one type of organism. Failing to state that the energy is released as ATP.

Mark scheme (4 marks)

  1. Cellular respiration is described as 'universal' because it occurs in all living cells
  2. It is a continuously occurring process (it never stops in living cells)
  3. Cellular respiration is described as 'exothermic' because it releases energy
  4. The energy released is in the form of ATP, from the breakdown of organic compounds such as glucose

Key terms in this question

cellular respiration

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