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3.6 Organisms respond to changes in their internal and external environments
Quick questions on Synaptic transmission: the cholinergic synapse, summation and the neuromuscular junction - AQA A-Level Biology
8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is structure of a synapse?Show answer
A synapse is the junction between two neurones. The presynaptic neurone ends in a swelling (synaptic knob) containing synaptic vesicles full of neurotransmitter and many mitochondria. A small gap, the synaptic cleft, separates it from the postsynaptic membrane, which carries receptor proteins.
What is transmission across a cholinergic synapse?Show answer
A cholinergic synapse uses the neurotransmitter acetylcholine (ACh). The sequence of events is:
What is the neuromuscular junction?Show answer
A neuromuscular junction is the synapse between a motor neurone and a skeletal muscle fibre. It works in the same basic way (acetylcholine is released and binds to receptors), but with key differences from a synapse between two neurones:
What is unidirectional transmission?Show answer
Transmission is one-way only because:
What are effects of drugs?Show answer
You may be asked to predict a drug's effect from a description of how it acts:
What is q1?Show answer
Describe the role of calcium ions in synaptic transmission. [2 marks]
What is q2?Show answer
Explain why transmission across a synapse occurs in one direction only. [2 marks]
What is q3?Show answer
Distinguish between spatial and temporal summation. [2 marks]