Question

Pepsin and trypsin are both protein digesting enzymes, but mostly active in the stomach and duodenum respectively because ____.

• A. pepsin acts in acidic pH and trypsin in alkaline pH
• B. pepsin acts in alkaline pH and trypsin in acidic pH
• C. in the stomach, the temperature is above \(40^{\circ }\)C and in the duodenum it is less than \(20^{\circ }\)C
• D. in the stomach, the temperature is below \(20^{\circ }\)C and in the duodenum it is above \(40^{\circ }\)C

Hint:

The two enzymes differ in their optimum pH: pepsin needs acid and trypsin needs alkaline conditions.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
Enzymes work best at a particular pH. Both pepsin and trypsin work at body temperature, so temperature does not explain the difference.

Step 2: Optimum pH
Pepsin is activated by HCl in the stomach and works at an acidic pH of about 1.5 to 2.
Trypsin comes from the pancreas and works in the duodenum, where bile and bicarbonate make the medium alkaline.

Step 3: Compare the options
Options (C) and (D) give wrong temperatures, and option (B) reverses the pH. Only option (A) is correct.

Final Answer:
Pepsin acts in acidic pH and trypsin in alkaline pH. \[ \boxed{\text{(A) }\text{pepsin acts in acidic pH and trypsin in alkaline pH}} \]