The nervous system uses two types of neurone to carry signals around the body. Explain how the structure of a motor neurone makes it well suited to its function.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
A motor neurone carries impulses from the central nervous system to an effector (muscle or gland). Its axon is long, allowing impulses to be carried over large distances quickly. The axon is wrapped in a myelin sheath, which insulates the axon and speeds up transmission of the nerve impulse. The cell body contains the nucleus and controls the metabolic activity of the neurone, providing the energy needed for impulse transmission.
Examiner tips
- Use the term ‘motor neurone’ and ‘effector’. Mention the long axon and myelin sheath. Explain how the cell body supplies energy. Keep each point concise to cover all four marks.
Common mistakes
- Confusing sensory with motor neurone. Omitting the myelin sheath. Failing to link the cell body to energy supply.
Mark scheme (4 marks)
- A motor neurone carries impulses from the central nervous system to an effector (muscle or gland)
- The axon is long, allowing impulses to be carried over large distances quickly
- The myelin sheath insulates the axon, speeding up transmission of the nerve impulse
- The cell body contains the nucleus and controls the metabolic activity of the neurone, providing the energy needed for impulse transmission
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →