A-LevelBiologyControl and coordination9700/43 · May/June 2019 · Q111 Marks

(a) Fig. 1.1 shows a cholinergic synapse. presynaptic knob [Figure 1.1]

(a)Complete Table 1.1, using the letters A, B, C or D from Fig. 1.1, to show the location of compounds and structures associated with a cholinergic synapse. You may use A, B, C and D once, more than once, or not at all. Table 1.1 compound or structure acetylcholine voltage-gated channel receptor protein acetylcholinesterase location[4]
(b)Explain what is meant by a voltage-gated channel.[2]
(c)Explain the role of acetylcholinesterase in a synapse.[3]
(d)Outline the roles of synapses in the nervous system.[2]

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Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[4] (a) acetylcholine C and D ; voltage-gated channel A; receptor protein B; acetylcholinesterase C;
[2] (b) any two from: 1 ref. to ion (transport); 2 open / closes, when, voltage / depolarisation / charge / electrical potential, changes ; A arrival of an action potential 3 detail ; e.g. ion specificity / hydrophilic pore / transmembrane / (made of) protein
[3] (c) any three from: 1 breaks down acetylcholine; 2 (so) acetylcholine leaves, binding site / receptor / B; ora 3 depolarisation stops in post-synaptic membrane / B ; 4 stops continuous action potentials (in post-synaptic membrane) ; 5 recycle ACh / described;
[2] (d) any two from: 1 one-way transmission ; 2 interconnection of nerve pathways ; 3 AVP ; e.g. memory / learning integration of impulses

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