IB Biology HL B2.1.14 Hl Gated Ion Channels in Neurons Topic Practice

a. (voltage-gated) potassium channels are closed when there is a negative membrane potential / when there are (relatively) more negative charges inside / (relatively) more positive charges outside;

b. (voltage-gated) potassium channels open after depolarization of the axon / after closing of sodium channels / when a positive membrane potential develops / at +30 mV / at +40 mV ;

c. $\mathrm{K}^{+}$ions diffuse out of the cell / efflux of $\mathrm{K}^{+}$;

d. (efflux of $\mathrm{K}^{+}$) causes/results in/happens during repolarization / membrane potential returns to -70 mV / to the resting potential;

e. (voltage-gated) potassium channels close again (to terminate the action potential) OR

globular protein ball (attached by a flexible chain of amino acids) blocks/closes the channel;

f. (following an action potential) hyperpolarization can occur (due to slow closing of potassium channels / continued efflux of $\mathrm{K}^{+}$before potassium channels close / nature of potassium channels);

3

Marking guidance:

max

neurotransmitter (gated ion channel) / ligand (gated ion channel) / mechanically (gated ion channel);

Marking guidance:

Do not accept examples.