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Module 5: Communication, homeostasis and energy
Quick questions on Neuronal communication: resting and action potentials, saltatory conduction and synapses - OCR A-Level Biology A
6short 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 neurone structure?Show answer
A neurone carries electrical impulses. A motor neurone has a cell body with dendrites (receive impulses), a long axon (carries the impulse), and an axon terminal. Many neurones are wrapped in a myelin sheath of Schwann cells, with gaps called nodes of Ranvier; myelin acts as an electrical insulator.
What is the resting potential?Show answer
At rest the inside of the axon is negative relative to the outside (about ), the resting potential. It is maintained by:
What is the action potential?Show answer
A stimulus changes the membrane potential. If it reaches the threshold (about ), an action potential fires:
What is q1?Show answer
Explain how the sodium-potassium pump helps maintain the resting potential. [2 marks]
What is q2?Show answer
Explain why saltatory conduction is faster than conduction in an unmyelinated axon. [2 marks]
What is q3?Show answer
Name the enzyme that breaks down acetylcholine in the synaptic cleft. [1 mark]
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