MCAT Biology Question 46: Answer and Explanation
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Question: 46
1. Resting membrane potential depends on:
differential distribution of ions across the axon membrane.
the opening of voltage-gated calcium channels.
active transport of ions across the membrane.
- A. I only
- B. I and II only
- C. I and III only
- D. II and III only
Correct Answer: C
Explanation:
The polarization of the neuron at rest is the result of an uneven distribution of ions between the inside and outside of the cell. This difference is achieved through the active pumping of ions into and out of the neuron (using the Na+/K+ ATPase). Voltage-gated calcium channels are important in the nerve terminal, where the influx of calcium triggers the fusion of vesicles containing neurotransmitter with the membrane, but not in maintaining resting membrane potential.