Explain why hormones are described as part of the endocrine system rather than the nervous system, giving two differences between the way hormones and nerve impulses are transmitted.

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

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

Model answer (4 marks)

Hormones are part of the endocrine system because they are chemical signals that travel through the bloodstream to reach target cells, whereas nerve impulses are electrical signals that travel along neurons.

1. Hormones are carried in the blood; nerve impulses travel along axons.
2. Hormonal responses are slow and long‑lasting, whereas nerve impulses are rapid and short‑lived.

Examiner tips

  • Use the word ‘endocrine’ and ‘nervous’ clearly; mention ‘blood’ vs ‘neurons’.
  • Show the two differences explicitly – transport medium and speed/lasting effect.
  • Keep the answer short and to the point to fit the 4 marks.

Common mistakes

  • Confusing the transport medium (mixing blood and axons).
  • Failing to mention both speed and duration differences.

Mark scheme (4 marks)

  1. Hormones travel in the blood (whereas nerve impulses travel along neurones)
  2. Hormonal responses are slow / take longer to reach the target organ (compared to nerve impulses which are rapid / instantaneous)
  3. Hormonal responses are long-lasting (whereas nerve impulse effects are short-lived / instantaneous)
  4. Hormones are chemical substances / signals (whereas the nervous system uses electrical signals / nerve impulses)

Key terms in this question

endocrine system · hormone · nerve impulse

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