IB Biology HL C2.2.9 Hl Action Potential Propagation Questions

Practise IB Biology HL 2.2.9 by applying action potential propagation concepts to exam questions.

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Explain how local currents from sodium-ion diffusion depolarize the next region of an axon to threshold during action-potential propagation.

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Study C2.2.9 (HL)—Action potential propagation conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 4]

Multicellular organisms benefit from cell specialization and division of labour.

Describe what occurs in a neuron when an action potential is propagated along the axon.

sodium ions/ $\mathrm{Na}^{+}$ enter/diffuse in;
depolarization/membrane potential/voltage changes from negative to positive;
potassium channels open AND potassium ions $/ \mathrm{K}^{+}$ exit /diffuse out;
repolarization/membrane potential/voltage changes back from positive to negative;
local current due to diffusion of sodium ions along the neuron;
(local currents) cause next sodium channels to open/next part of axon to depolarize;
opening of sodium channels triggered when threshold potential/ -50 mV reached;

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IB Biology HL C2.2.9 Hl Action Potential Propagation Questions question 1