Adrenaline and insulin are both hormones that affect blood glucose concentration. Compare how adrenaline and insulin each affect blood glucose concentration, and explain how each hormone reaches its target organ.

Cambridge International IGCSE Biology (0610) — 14.3 Hormones · Compare · 4 marks · View as Markdown

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

Model answer (4 marks)

Adrenaline raises blood glucose by stimulating glycogenolysis in liver and muscle cells, releasing glucose into the bloodstream.
Insulin lowers blood glucose by promoting glucose uptake into liver and muscle cells and stimulating glycogen synthesis.
Both hormones are secreted by endocrine glands (adrenal medulla for adrenaline, pancreas for insulin) directly into the bloodstream, where they travel to their target organs.

Examiner tips

  • Use the word ‘raises’ for adrenaline and ‘lowers’ for insulin to show comparison. Mention the specific tissues (liver/muscle) for each hormone. Show the route: gland → bloodstream → target organ.
  • common_mistakes
  • :
  • Confusing the direction of glucose change (e.g. saying adrenaline lowers glucose). Omitting the specific tissues affected. Failing to state that both hormones act via the bloodstream.

Mark scheme (4 marks)

  1. Adrenaline increases blood glucose concentration whereas insulin decreases blood glucose concentration.
  2. Adrenaline causes glycogen to be converted to glucose (in the liver/cells), raising blood glucose concentration.
  3. Insulin causes liver and muscle cells to increase uptake of glucose and/or conversion of glucose to glycogen.
  4. Both hormones are secreted by endocrine glands directly into the bloodstream and travel in the blood to their target organs.

Key terms in this question

adrenaline · insulin · blood glucose concentration · target organ

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