Cambridge A Level Biology A2 Action Potential Sequence Questions

[Maximum number: 4]

Fig. 7.1 is a diagram representing a synapse between a chemoreceptor cell from a human taste bud and a dendrite of a sensory neurone.

Fig. 7.1

In an experiment, different concentrations of sodium chloride solution were applied to the microvilli of the chemoreceptor cell. The membrane potential of the chemoreceptor cell and the membrane potential of the dendrite of the sensory neurone were recorded for each concentration.

The resting potential of this chemoreceptor cell is -50 mV and the resting potential of the dendrite of this sensory neurone is -70 mV .

The results are shown in Table 7.1.

Table 7.1

Explain the results shown in Table 7.1.

any four from:

$10.1 \mathrm{~g} \mathrm{dm}^{-3}$ chemoreceptor (membrane), is not depolarised / does not release neurotransmitter / remains at resting potential ;

2 so, dendrite / sensory neurone, is not depolarised / remains at resting potential / has no action potential ;

$31.0 \mathrm{~g} \mathrm{dm}^{-3} / 10.0 \mathrm{~g} \mathrm{dm}^{-3}$ , chemoreceptor (membrane), is depolarised / releases neurotransmitter ;

4 so, depolarisation / action potential / impulse, in, dendrite / sensory neurone ;

5 receptor/generator, potential qualified ;

6 ref. to threshold / all or nothing law (in context of either cell) ;

CAIE A-Level Biology A2 15.1.5 Action Potential Sequence Questions

Exam points

CAIE A-Level Biology A2 15.1.5 Action Potential Sequence Questions question 1