MCAT Biology Question 123: Answer and Explanation
Home > MCAT Test > MCAT biology practice tests
Test Information
- Use your browser's back button to return to your test results.
- Do more MCAT biology practice tests.
Question: 123
3. In an experiment, enteropeptidase secretion was blocked. As a direct result, levels of all of the following active enzymes would likely be affected EXCEPT:
- A. trypsin.
- B. aminopeptidase.
- C. chymotrypsin.
- D. carboxypeptidase A.
Correct Answer: B
Explanation:
Aminopeptidase is a brush-border peptidase secreted by the cells lining the duodenum; it does not require enteropeptidase for activation. Both trypsinogen and procarboxypeptidases A and B are activated by enteropeptidase, eliminating choices (A) and (D). Once activated, trypsin can activate chymotrypsinogen; if trypsinogen cannot be activated, then chymotrypsinogen will not be activated either, eliminating choice (C).