MCAT Biochemistry Question 108: Answer and Explanation
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Question: 108
3. Resting membrane potential depends on:
I. the differential distribution of ions across the membrane.
II. active transport processes.
III. selective permeability of the phospholipid bilayer.
- A. I only
- B. I and III only
- C. II and III only
- D. I, II, and III
Correct Answer: D
Explanation:
The polarization of the membrane 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 (predominantly sodium and potassium) into and out of the cell and the selective permeability of the membrane, which allows only certain ions to cross.