Answer
The following diagram is of a neurone in the mammalian nervous system.
(a) Label the structures numbered 1 through to 6.
1. axon
2. Schwann cell / Schwann cell nucleus
3. Node of Ranvier
4. Cell body
5. Dendrites
6. Dendritic knob / synaptic knob / sensory ending
[ 6 ]
(b) Identify the type of neurone shown in the diagram above.
(ii) Effector / motor / multipolar
[ 1 ]
(c) Identify the role of the neurone identified in the diagram.
Transmit / eq impulses to effectors / muscles / glands / named eg.
[ 1 ]
(d) Explain the importance of the structures labelled 5 in the diagram.
(forms) link/eq with sensory / relay neurone / reference to summation
[ 1 ]
(v) Describe the structure labelled 3 in the diagram and its importance in neurone
functioning.
Gap in the myelin sheath /eq ; enables depolarisation/action potential/eq (of axon) ; causes impulse to jump from node to node / saltatory conduction; speeds up (transmission of) impulse
[ 3 ]
[Total: 12 marks]