A zymogen is an inactive substance which is made active with the help of difference enzymes. Pepsinogen is secreted as a zymogen into the stomach to

Options

A. change the pH of the stomach fluids to aid digestion
B. digest complex carbohydrates.
C. digest tough cellulose material
D. prevent digestion of the gastric glands

Answer

To solve the question regarding the function of pepsinogen, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Zymogens**:
- A zymogen is an inactive precursor of an enzyme. It requires a biochemical change to become an active enzyme.

2. **Identifying Pepsinogen**:
- Pepsinogen is a specific type of zymogen that is secreted by the gastric chief cells in the stomach. It is the inactive form of the enzyme pepsin.

3. **Function of Pepsin**:
- Once activated, pepsin functions primarily to digest proteins. It breaks down complex protein molecules into smaller peptides.

4. **Reason for Secretion as Zymogen**:
- Pepsinogen is secreted in its inactive form to prevent the premature digestion of the gastric glands themselves. If pepsin were active in the gastric glands, it could lead to self-digestion of these cells.

5. **Analyzing the Options**:
- Option A: Change the pH of the stomach fluids to aid digestion - Incorrect, as pepsinogen does not change pH.
- Option B: Digest complex carbohydrates - Incorrect, as pepsinogen is not involved in carbohydrate digestion.
- Option C: Digest tough cellulose material - Incorrect, as pepsinogen does not digest cellulose.
- Option D: Prevent Digestion of Gastric Glands - Correct, as pepsinogen is secreted to prevent the digestion of the gastric glands.

6. **Conclusion**:
- Therefore, the correct answer to the question is **Option D**: Pepsinogen is secreted as a zymogen into the stomach to prevent digestion of gastric glands.