Which of the following , does not help in clotting of blood ?

Options

A. (a) Heparin
B. (b) Prothrombin
C. (c) `Ca^(2+)`
D. (d) exposure to `O_2 `

Answer

To solve the question "Which of the following does not help in clotting of blood?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks us to identify which option does not assist in the process of blood clotting.

2. **Review the Options**: We need to evaluate each option provided to determine its role in blood clotting.

3. **Analyze Heparin**:
- Heparin is a substance that is produced by basophils and mast cells in the body.
- It acts as a natural anticoagulant, meaning it prevents blood clotting by dissolving unwanted clots.
- Therefore, Heparin does not help in clotting; instead, it inhibits the process.

4. **Evaluate Other Options**:
- **Prothrombin**: This is a protein that is essential for blood clotting as it is converted into thrombin during the clotting process.
- **Calcium**: Calcium ions play a crucial role in the coagulation cascade and are necessary for various steps in the clotting process.
- **Exposure to Oxygen**: Oxygen exposure is important for the activation of certain clotting factors and for the overall healing process.

5. **Conclusion**: Since Heparin is the only substance that acts as an anticoagulant and prevents clotting, it is the correct answer to the question.

### Final Answer:
Heparin does not help in the clotting of blood.

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