Describe how the hormone glucagon returns blood glucose levels to normal after they have fallen too low. Include the role of negative feedback in your answer.

AQA GCSE Biology (8461) — 4.5.3 Hormonal coordination in humans · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Glucagon is released by the pancreas when blood glucose falls.
1. It stimulates liver cells to break down glycogen into glucose.
2. The glucose is released into the bloodstream.
3. Blood glucose rises back towards normal.
4. The increased glucose level stops further glucagon release – a negative‑feedback loop.

Examiner tips

  • Use the exact terms ‘glucagon’, ‘pancreas’, ‘glycogen’, ‘liver’, ‘negative feedback’.
  • Show the sequence: low glucose → glucagon release → glycogenolysis → glucose ↑ → feedback stops glucagon.
  • Keep answer short – one sentence per point.

Common mistakes

  • Confusing insulin with glucagon.
  • Not mentioning the pancreas as the source of glucagon.
  • Failing to state that the rise in glucose stops glucagon release.

Mark scheme (4 marks)

  1. Glucagon is produced by the pancreas
  2. Glucagon causes glycogen to be converted into glucose
  3. Glucose is released into the blood, raising blood glucose levels
  4. This is negative feedback because the rise in blood glucose inhibits / reverses the original change (low blood glucose)

Key terms in this question

glucagon

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