MCAT Biochemistry Question 73: Answer and Explanation
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Question: 73
13. Which of the following is true about cholesterol?
- A. Cholesterol always increases membrane fluidity in cells.
- B. Cholesterol is a steroid precursor.
- C. Cholesterol is a precursor for vitamin A, which is produced in the skin.
- D. Cholesterol interacts only with the hydrophobic tails of phospholipids.
Correct Answer: B
Explanation:
Cholesterol is a steroid precursor that has variable effects on membrane fluidity depending on temperature, eliminating choice (A). It interacts with both the hydrophobic tails and the hydrophilic heads of membrane lipids, nullifying choice (D). It is also a precursor for vitamin D (not vitamin A), which can be produced in the skin in a UV-driven reaction, eliminating choice (C).