Compare the structure and function of a sensory neurone and a motor neurone.

Eduqas GCSE Biology — 2.5.1 The nervous system · Compare · 4 marks · View as Markdown

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

Model answer (4 marks)

A sensory neurone carries impulses from a receptor to the CNS, whereas a motor neurone carries impulses from the CNS to an effector.
A sensory neurone has a long dendron carrying the impulse towards the cell body, whereas a motor neurone has many short dendrites receiving impulses at the cell body.
Both neurones have an axon that carries the impulse away from the cell body.
Both neurones may be covered in a myelin sheath, which insulates the neurone and speeds up the transmission of impulses.

Examiner tips

  • Use the word ‘compare’ to list similarities and differences clearly.
  • Mention the direction of impulse flow for each type.
  • Include the key structural features (dendron/dendrites, axon, myelin).

Common mistakes

  • Confusing the direction of impulse flow (e.g., saying sensory goes to effector).
  • Omitting the myelin sheath detail or mixing up dendron vs dendrites.

Mark scheme (4 marks)

  1. A sensory neurone carries impulses from a receptor (to the CNS), whereas a motor neurone carries impulses from the CNS to an effector.
  2. A sensory neurone has a long dendron carrying the impulse towards the cell body, whereas a motor neurone has many short dendrites receiving impulses at the cell body.
  3. Both neurones have an axon that carries the impulse away from the cell body.
  4. Both neurones may be covered in a myelin sheath, which insulates the neurone and speeds up the transmission of impulses.

Key terms in this question

sensory neurone · motor neurone

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