Explain how adrenaline prepares the body for a fight or flight response.

OCR GCSE Biology A: Gateway Science (J247) — B3.2 Coordination and control — the endocrine system · Explain · 4 marks · View as Markdown

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

A student is walking home alone at night when a large dog runs towards them barking aggressively. Within seconds, the student's heart is pounding and they feel ready to run.

Model answer (4 marks)

Adrenaline is released by the adrenal gland
Adrenaline is transported in the bloodstream to target organs
Adrenaline increases heart rate (and breathing rate)
Adrenaline raises blood glucose levels by converting glycogen into glucose (providing more energy for muscles)

Examiner tips

  • Use the exact wording from the mark scheme (e.g. "adrenaline is released by the adrenal gland").
  • Show the sequence: release → transport → action on heart, lungs, liver.
  • Mention the physiological effect (e.g. "increases heart rate and breathing rate").
  • Include the metabolic effect on glucose for energy supply.

Common mistakes

  • Confusing adrenaline with noradrenaline or cortisol.
  • Omitting the transport step or the effect on blood glucose.
  • Using vague terms like "fast heart" instead of "increases heart rate".

Mark scheme (4 marks)

  1. Adrenaline is released by the adrenal gland
  2. Adrenaline is transported in the bloodstream to target organs
  3. Adrenaline increases heart rate (and breathing rate)
  4. Adrenaline raises blood glucose levels by converting glycogen into glucose (providing more energy for muscles)

Key terms in this question

adrenaline · fight or flight

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