Digestionof both starch and protein is carried out by

Options

A. Gastric juice
B. Gastric lipase
C. Pancreatic juice
D. Ptyalin.

Answer

To answer the question regarding which substance is responsible for the digestion of both starch and protein, we can analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding the Components**:
- The question asks about the digestion of both starch and protein. We need to identify which of the given options can facilitate the breakdown of both these macromolecules.

2. **Analyzing Option 1: Gastric Juice**:
- Gastric juice contains hydrochloric acid (HCl), pepsin, and gastric lipase.
- Pepsin is responsible for protein digestion, but gastric juice does not digest starch. Therefore, this option cannot be correct.

3. **Analyzing Option 2: Gastric Lipase**:
- Gastric lipase is an enzyme that primarily acts on fats (lipids) and is secreted by gastric chief cells.
- It does not play a role in the digestion of starch or protein. Thus, this option is also incorrect.

4. **Analyzing Option 3: Pancreatic Juice**:
- Pancreatic juice is secreted by the pancreas and contains several important enzymes:
- **Amylase**: Breaks down starch into maltose.
- **Trypsin**: Breaks down proteins into smaller peptides (peptones).
- **Lipase**: Breaks down fats.
- Since pancreatic juice contains both amylase (for starch) and trypsin (for protein), it is capable of digesting both macromolecules. This makes this option the correct answer.

5. **Analyzing Option 4: Ptyalin**:
- Ptyalin is a form of amylase found in saliva that digests starch into maltose.
- However, it does not digest proteins. Therefore, this option cannot be correct.

### Conclusion:
Based on the analysis, the correct answer is **Pancreatic Juice** (Option 3), as it contains enzymes that digest both starch and protein.