Explain why it is important for the human body to maintain a constant internal temperature.

Eduqas GCSE Biology — 2.5.3 Homeostasis · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Enzymes in the body work best at their optimum temperature of 37 °C. If the internal temperature rises or falls, the enzyme’s shape, especially the active site, changes. This prevents the substrate from fitting or binding correctly. Consequently, metabolic and other chemical reactions in the body slow down or stop, impairing normal function.

Examiner tips

  • Use the term ‘optimum temperature’ and give 37 °C; link temperature to enzyme shape and activity; explain the consequence for metabolism; keep answer concise and to the point.

Common mistakes

  • Failing to mention 37 °C or ‘optimum temperature’; confusing temperature change with pH change; not linking enzyme shape to reaction rate; writing a long paragraph instead of clear points.

Mark scheme (4 marks)

  1. Enzymes work best / at their optimum at a specific/normal body temperature (37 °C)
  2. If temperature changes, the enzyme's shape / active site changes
  3. This means the substrate can no longer fit / bind to the active site
  4. So metabolic reactions / chemical reactions in the body slow down or stop

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