Neurones and the reflex arcEdexcel International A Level Biology: Mind map

Exam questions on Neurones and the reflex arc

1. A person touches a hot saucepan handle and pulls their hand away before they feel any pain. The withdrawal is a spinal reflex.
   Explain why the withdrawal reflex is faster than a conscious, voluntary response.2 marks
2. A neurobiologist examines a transverse section through a human spinal cord and a longitudinal section through a motor neurone with its myelin sheath.
   Describe how Schwann cells form a myelin sheath and explain why the sheath insulates the axon.2 marks
3. A child steps on a sharp drawing pin and lifts her foot straight away. A student describes the pathway. A receptor in the skin detects the pin. A neurone carries the impulse into the spinal cord through the dorsal root, and the cell body of this neurone lies in a swelling outside the cord. In the spinal cord the impulse passes across a synapse to a short neurone, then across a second synapse to a neurone that leaves the cord through the ventral root and reaches a muscle in the leg.
   Describe the pathway of the impulse in this reflex, from the receptor to the response, naming the types of neurone involved.3 marks