Different species of animal have neurones with different characteristics. (a) Fig. 1.1 is a diagram of a motor neurone of a rat and a motor neurone of a snail. [Figure 1.1]

1. (a)(i)Name the structures labelled A, B and C on Fig. 1.1. A B C[3]
2. (a)(ii)The rat motor neurone has an impulse transmission speed of 50ms¯¹. The snail motor neurone has an impulse transmission speed of 8 ms-1. Explain why the rat motor neurone has a faster impulse transmission speed than the snail motor neurone.[2]
3. (b)Fig. 1.2 shows an action potential in a rat neurone and Fig. 1.3 shows an action potential in a snail neurone. [Figure 1.2] [Figure 1.3] Contrast the two action potentials shown in Fig. 1.2 and Fig. 1.3.[3]

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