Which of the following is incorrect regarding the given digestion and absorption of protein?

Options

A. The breakdwon of proteins to peptides is catalyzed by pepsin in the stomach and by the pancreatic enzymes trypsin and chymotrypsin in the small intestine.
B. Peptides are broken down into amono acids by pancreatic carboxypeptidase and intestinal aminopeptidase.
C. Small peptides consisting of two or three amono acids can diffuse through epithelial cell and broken down into carbon dioxide and ammonia which are released into the blood.
D. none of these

Explanation

To solve the question regarding the incorrect statement about the digestion and absorption of proteins, we will analyze each statement provided.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- The statement claims that the breakdown of proteins to peptides is catalyzed by pepsin in the stomach and by pancreatic enzymes trypsin and chymotrypsin in the small intestine.
- **Evaluation:** This statement is true. Pepsin is indeed responsible for protein digestion in the stomach, while trypsin and chymotrypsin, which are secreted by the pancreas, further digest proteins in the small intestine.

2. **Analyze the Second Statement:**
- The statement mentions that peptides are broken down into amino acids by pancreatic carboxypeptidase and intestinal aminopeptidase.
- **Evaluation:** This statement is also true. Carboxypeptidase (from the pancreas) and aminopeptidase (from the intestinal lining) are enzymes that break down peptides into amino acids.

3. **Analyze the Third Statement:**
- The statement says that small peptides consisting of two or three amino acids can diffuse through the epithelial cell and are broken down into carbon dioxide and ammonia, which are released into the blood.
- **Evaluation:** This statement is false. Small peptides, specifically dipeptides and tripeptides, do not break down into carbon dioxide and ammonia. Instead, they are further hydrolyzed into amino acids, which are then absorbed into the bloodstream.

4. **Conclusion:**
- The incorrect statement regarding the digestion and absorption of proteins is the third statement. Thus, the answer to the question is the third statement.

### Final Answer:
The incorrect statement is: "Small peptides consisting of two or three amino acids can diffuse through epithelial cells and are broken down into carbon dioxide and ammonia which are released into the blood."

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