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]

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