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CAIE A-Level Biology A2 15.1.6 Membrane Potential Changes Questions

Explain membrane potential changes during an action potential using evidence from each question and mark scheme.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Explain membrane potential changes during an action potential.

CAIE A-Level Biology A2 15.1.6 Membrane Potential Changes Questions question 1

[Maximum number: 5]

Question (a)

(a)

Fig. 8.1 shows the changes in potential difference (p.d.) across the membrane of a receptor cell over a period of time. The membrane was stimulated at time A and at time B with stimuli of different intensities.

Fig. 8.1

Fig. 8.1

[ 5 ]

Question (i)

(i)

State which of the letters C, D and E on Fig. 8.1 correspond to each of these events. You may use each of the letters C, D or E once, more than once or not at all.

The Na+/K+\mathrm{Na}^{+} / \mathrm{K}^{+}pump is operating
The voltage-gated Na+\mathrm{Na}^{+}channels are open
The voltage-gated K+\mathrm{K}^{+}channels are open

[ 3 ]

Question (ii)

(ii)

Explain why stimulus A did not result in an action potential being produced whereas stimulus B did.

[ 2 ]
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