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

Eduqas GCSE Biology — 4.3 Homeostasis in humans · 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 have an optimum temperature and pH; if the internal environment deviates, enzyme activity falls or enzymes denature.
This reduces or stops metabolic reactions that are essential for cell function.
Consequently, organ and tissue function is impaired, threatening survival.
Therefore the body must keep temperature and pH constant to allow normal biochemical processes and maintain life.

Examiner tips

  • Use the word ‘optimum’ for temperature/pH. Show the link: enzyme → reaction rate → organ function → survival. Keep each point short and to the point.

Common mistakes

  • Confusing external temperature with body temperature. Failing to mention pH or only citing temperature. Using vague terms like ‘good conditions’ instead of ‘optimum temperature/pH’.

Mark scheme (4 marks)

  1. Enzymes work best at a specific/optimum temperature (or pH)
  2. If conditions change, enzyme activity decreases / enzymes may denature
  3. This would slow down or stop metabolic reactions / chemical reactions in cells
  4. Maintaining constant conditions allows cells/organs to function correctly / ensures survival

Key terms in this question

internal environment

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