Prothrombin is found in-
(a) Intestine and helps in cellulose digestion
(b) Liver and helps in the production of bile
(c) Blood and gives red color
(d) Blood and helps in blood clotting

Options

A. Intestine and helps in cellulose digestion
B. Liver and helps in the production of bile
C. Blood and gives red color
D. Blood and helps in blood clotting

Answer

To determine where prothrombin is found and its function, let's analyze each option step by step.

1. **Understanding Prothrombin**: Prothrombin is a plasma protein that plays a crucial role in the blood clotting process. It is not involved in digestion or bile production.

2. **Evaluating Option A**:
- **Statement**: "Prothrombin is found in the intestine and helps in cellulose digestion."
- **Analysis**: This statement is incorrect. Prothrombin is not found in the intestine, and it does not aid in cellulose digestion. Cellulose digestion is primarily carried out by certain microorganisms and enzymes, not prothrombin.

3. **Evaluating Option B**:
- **Statement**: "Prothrombin is found in the liver and helps in the production of bile."
- **Analysis**: This statement is also incorrect. While the liver does produce prothrombin, prothrombin itself does not help in the production of bile. Bile is produced by the liver but is composed of bile salts, bilirubin, cholesterol, and other substances.

4. **Evaluating Option C**:
- **Statement**: "Prothrombin is found in blood and gives red color."
- **Analysis**: This statement is incorrect. Prothrombin is found in the blood, but it does not give blood its red color. The red color of blood is due to hemoglobin, not prothrombin.

5. **Evaluating Option D**:
- **Statement**: "Prothrombin is found in blood and helps in blood clotting."
- **Analysis**: This statement is correct. Prothrombin is indeed found in blood and plays a vital role in the blood clotting process. It is converted into thrombin in the presence of thromboplastin, which is released by platelets during an injury. Thrombin then converts fibrinogen into fibrin, leading to the formation of a blood clot.

**Conclusion**: The correct answer is (d) Blood and helps in blood clotting.

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