A soluble clotting factor that is made insoluble by thrombin is ………….

Options

A. prothrmbin
B. fibrinogen
C. fibrin
D. calcium ions

Answer

**Step-by-Step Solution:**

1. **Understanding Blood Clotting**: When an injury occurs, blood begins to flow out. The body has a mechanism to stop this bleeding through a process called blood clotting.

2. **Role of Clotting Factors**: Blood clotting involves various clotting factors, which are proteins in the blood that help in the clotting process.

3. **Conversion of Prothrombin to Thrombin**: When an injury happens, a series of enzymatic reactions are triggered. One of the key steps is the conversion of prothrombin (a soluble protein) into thrombin, which is facilitated by an enzyme known as factor X (or prothrombinase).

4. **Thrombin's Function**: Thrombin plays a crucial role in the clotting process. It converts fibrinogen, another soluble protein, into fibrin, which is an insoluble protein.

5. **Formation of the Blood Clot**: The insoluble fibrin, along with platelets, forms a gel-like structure that constitutes the blood clot, effectively stopping the bleeding.

6. **Identifying the Correct Answer**: Based on the information, the soluble clotting factor that is made insoluble by thrombin is fibrinogen. Other options like prothrombin and calcium ions do not fit this description.

7. **Conclusion**: Therefore, the correct answer is fibrinogen.

**Final Answer**: Fibrinogen

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