Question 6(a)
[Maximum number: 4]
A reflex is a rapid response to a stimulus.
The withdrawal of a hand when a finger touches a hot object is an example of a reflex.
Describe the pathway of a nerve impulse in the reflex arc involved in this response.
Edexcel IGCSE Biology 2.90 reflex arc
Practise reflex arc questions by labelling the withdrawal pathway and explaining why measured response time includes synaptic delays.
How this is tested
- Trace impulses from skin receptors through sensory, relay and motor neurones to effectors.
- Identify reflex-arc structures such as receptors, effectors and motor neurones on diagrams.
- Explain why response time includes synapse delays, not just travel along neurones.