IB Biology HL C2.2.2 Resting Potential Generation Questions

Trace how ATP-powered sodium-potassium pumps move three Na⁺ out for every two K⁺ in, maintaining ion gradients and an axon’s negative resting potential.

Exam points

Define resting potential and state its approximate membrane-potential value (about −70 mV).
Explain how the sodium-potassium pump uses ATP to move 3 Na⁺ out and 2 K⁺ in, maintaining axon ion gradients and polarization.

[Maximum number: 4]

Outline how neurons generate a resting potential.

a	sodium-potassium pump
b	sodium $/ \mathrm{Na}^{+}$ out and potassium $/ \mathrm{K}^{+}$ in OR sodium $/ \mathrm{Na}^{+}$ concentration higher outside and potassium $/ \mathrm{K}^{+}$ higher inside
c	three $\mathrm{Na}^{+}$ pumped for every two $\mathrm{K}^{+}$ (hence negative inside) OR inside of axon holds negative ions/ $\mathrm{Cl}^{-}$ ions/negatively charged proteins/organic anions (hence negative inside)
d	by active transport / using ATP
e	inside (of axon/neuron) is negative in comparison to outside OR electrochemical concentration/charge difference (across the membrane) is the resting potential
f	resting potential is -70 mV

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IB Biology HL C2.2.2 Resting Potential Generation Questions question 1