Which is not a plasma protein `-`

Options

A. Fibrinogen
B. Heparin
C. Albumin
D. Prothrombin

Answer

**Step-by-Step Solution:**

1. **Understanding Plasma Proteins**: Plasma proteins are proteins found in blood plasma. They include a variety of proteins such as albumin, fibrinogen, and globulins, which play crucial roles in maintaining blood volume, blood clotting, and immune responses.

2. **Analyzing the Options**: The question asks to identify which of the provided options is not a plasma protein. The options given are:
- A) Fibrinogen
- B) Heparin
- C) Albumin
- D) Prothrombin

3. **Identifying Each Protein**:
- **Fibrinogen**: This is a plasma protein produced by the liver that is essential for blood clotting. It helps in forming blood clots to stop bleeding.
- **Heparin**: This is an anticoagulant, which means it prevents blood clotting. Heparin is not classified as a plasma protein.
- **Albumin**: This is a major plasma protein also produced by the liver. It helps maintain osmotic pressure and transports various substances in the blood.
- **Prothrombin**: This is another plasma protein that plays a critical role in blood clotting, also produced by the liver.

4. **Conclusion**: Among the options, heparin is the only one that is not a plasma protein. Therefore, the correct answer is **Heparin**.

**Final Answer**: Heparin is not a plasma protein.

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