Pepsin, a protein-digesting enzyme in the stomach, has its optimum activity at a pH of about ____.
Correct answer B. 2
Explanation
Pepsin works in the strongly acidic gastric juice produced by HCl secretion, so its optimum pH is about 2. Trypsin, acting in the small intestine, works best at about pH 8.
Answer checked How we write and check questions
Discussion