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Give two reasons why transmission across a cholinergic synapse is unidirectional - AQA - A-Level Biology - Question 7 - 2022 - Paper 1
Question 7
Give two reasons why transmission across a cholinergic synapse is unidirectional. 1. Only the presynaptic neurone releases acetylcholine. 2. Only the postsynaptic ... show full transcript
Worked Solution & Example Answer:Give two reasons why transmission across a cholinergic synapse is unidirectional - AQA - A-Level Biology - Question 7 - 2022 - Paper 1
Step 1
1. Only the presynaptic neurone releases neurotransmitter
Answer
In a cholinergic synapse, the presynaptic neuron is responsible for releasing the neurotransmitter acetylcholine. This release occurs when an action potential reaches the presynaptic terminal, causing vesicles containing acetylcholine to fuse with the membrane and release the neurotransmitter into the synaptic cleft.
Step 2
2. Only the postsynaptic neurone has receptors
Answer
The postsynaptic neurone has specific receptors for acetylcholine, allowing it to bind and trigger a response. This ensures that the signal can only be transmitted in one direction, from presynaptic to postsynaptic neurone, as the neurotransmitter does not act on the presynaptic side.