Question

The enzyme 'pepsin' is inactive in stomach without the presence of :

• A. Nitric Acid
• B. Hydrochloric Acid
• C. Acetic Acid
• D. Butyric Acid

Hint:

The stomach's highly acidic environment, primarily due to hydrochloric acid, is vital for two main reasons: activating pepsinogen into active pepsin for protein digestion and killing most bacteria ingested with food.

Answer 1

The Correct Option is B

Step 1: Understand the function of pepsin.
Pepsin is a protease enzyme in the stomach that initiates protein digestion. It is secreted by the chief cells of the stomach lining in an inactive form called pepsinogen to prevent it from digesting the stomach wall itself. Step 2: Identify the condition required for pepsin's activation.
Pepsinogen requires an acidic environment to convert into active pepsin. The stomach provides this acidic environment through the secretion of a specific acid. Step 3: Determine which acid is present in the stomach.
The stomach secretes hydrochloric acid (HCl), which creates a highly acidic environment (pH typically between 1.5 and 3.5). This low pH is crucial for the activation of pepsinogen to pepsin and for pepsin's optimal activity. Step 4: Evaluate the given options.
(1) Nitric Acid: Not naturally present in the stomach.
(2) Hydrochloric Acid: This is the acid secreted by the stomach lining, essential for activating pepsinogen to pepsin and for its function.
(3) Acetic Acid: Not naturally present in the stomach in significant amounts to activate pepsin.
(4) Butyric Acid: Not naturally present in the stomach. Step 5: Conclude the correct acid.
The enzyme pepsin is inactive in the stomach without the presence of Hydrochloric Acid, which provides the necessary acidic environment for its activation. $$(2) Hydrochloric Acid$$