A drop of each of the following, is placed separately on four sides. Which of them will not coagulate ?

Options

A. Blood serum
B. Sample from the thoracic duct of lymphatic system
C. Whole blood from pulmonary vein
D. Blood plasma

Answer

To solve the question of which of the following will not coagulate when placed on separate sides, we need to analyze each option provided:

### Step-by-Step Solution:

1. **Understanding the Components**:
- We have four options:
1. Blood serum
2. Sample from the thoracic duct of the lymphatic system
3. Whole blood from the pulmonary vein
4. Blood plasma

2. **Analyzing Blood Plasma**:
- Blood plasma contains red blood cells (RBCs), white blood cells (WBCs), platelets, and most importantly, clotting factors.
- Since it has clotting factors, blood plasma will coagulate when exposed.
- **Conclusion**: Blood plasma coagulates.

3. **Analyzing Whole Blood from the Pulmonary Vein**:
- Whole blood, regardless of whether it is from the pulmonary vein or any other source, contains RBCs, WBCs, platelets, and clotting factors.
- Therefore, whole blood will also coagulate.
- **Conclusion**: Whole blood coagulates.

4. **Analyzing the Sample from the Thoracic Duct**:
- The thoracic duct contains lymph, which does have some clotting factors, but the coagulation process in lymph is slower compared to blood.
- Although lymph can coagulate, it does so at a slower rate.
- **Conclusion**: The sample from the thoracic duct can coagulate, but it is not as rapid as blood coagulation.

5. **Analyzing Blood Serum**:
- Blood serum is the fluid part of blood that remains after coagulation has occurred. It lacks clotting factors because they are consumed during the coagulation process.
- Therefore, blood serum will not coagulate.
- **Conclusion**: Blood serum does not coagulate.

### Final Answer:
The component that will not coagulate is **Blood Serum** (Option 1).

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