IB Biology SL 2.2.3 Nerve impulses as action potentials Question Bank

Practise IB Biology SL 2.2.3 by explaining how ion movement creates and transmits an action potential.

Exam points

Explain how sodium and potassium ion movement changes membrane potential during an impulse.
Describe how an action potential travels along a nerve fibre.

[Maximum number: 3]

The diagram below shows a motor neuron.

Figure for Question C2.2.3—Nerve impulses as action potentials question 1 — IB Biology SL

Outline how nerve impulses are transmitted along a nerve fibre.

a. (sodium channels/voltage-gated channels open and) $\mathrm{Na}^{+}$ diffuse into neuron (down concentration gradient);
b. inside of neuron becomes positive compared to outside / potential is reversed / depolarization;
c. wave of depolarization moves (down the membrane);
d. (potassium channels open and) $\mathrm{K}^{+}$ diffuse out (down concentration gradient);
e. inside becomes negative compared with outside / potential across membrane restored / repolarization;
f. active transport of $\mathrm{K}^{+}$ (into neuron) and $\mathrm{Na}^{+}$ (out of neuron) restores resting potential;

All question bank results loaded

C2.2.3—Nerve impulses as action potentials question 1