MCAT Biology Question 9: Answer and Explanation
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Question: 9
9. Which of the following is NOT a difference that would allow one to distinguish a prokaryotic and a eukaryotic cell?
- A. Ribosomal subunit weight
- B. Presence of a nucleus
- C. Presence of a membrane on the outside surface of the cell
- D. Presence of membrane-bound organelles
Correct Answer: C
Explanation:
The main differences between prokaryotes and eukaryotes include: prokaryotes do not have a nucleus, while eukaryotes do, eliminating choice (B); prokaryotes have ribosomal subunits of 30S and 50S, while eukaryotes have ribosomal subunits of 40S and 60S, eliminating choice (A); and prokaryotes do not have membrane-bound organelles, whereas eukaryotes do, eliminating choice (D). The presence of a membrane on the outer surface of the cell could not distinguish a prokaryotic cell from a eukaryotic one because both gram-negative bacteria and animal cells share this feature. Thus, choice (C) is the correct answer.