You are required to draw blood from a patient and to keep in it a test tube for analysis of blood corpuscles and plasma. You are also provided with the following four types of test tubes. Which of them will you not use for the purpose.

Options

A. Test-tube containing calcium bicarbonate
B. Chilled test tube
C. Test tube containing heparin
D. Test tube containing sodium oxalate

Explanation

To determine which test tube should not be used for drawing blood for analysis of blood corpuscles and plasma, we need to consider the role of calcium in the blood clotting process. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understand the Components of Blood**: Blood consists of two main components: blood corpuscles (cells) and plasma. Plasma contains proteins, including clotting factors.

2. **Recognize the Clotting Mechanism**: When blood is drawn, it has a tendency to clot due to the presence of clotting proteins and calcium ions. The clotting cascade involves several steps, ultimately leading to the formation of fibrin, which creates a clot.

3. **Identify the Role of Calcium**: Calcium ions are crucial for the clotting process. They help in the conversion of prothrombin to thrombin, which then activates fibrinogen to fibrin, leading to clot formation.

4. **Examine the Test Tube Options**: You have four types of test tubes to consider:
- Test tube containing calcium bicarbonate
- Chilled test tube
- Test tube containing heparin
- Test tube containing calcium oxalate

5. **Evaluate Each Option**:
- **Calcium Bicarbonate**: This contains calcium, which will promote clotting. Therefore, it is not suitable for keeping blood for analysis.
- **Chilled Test Tube**: Chilling slows down enzymatic reactions, but it does not promote clotting. It can be used for analysis.
- **Test Tube Containing Heparin**: Heparin is a natural anticoagulant that prevents clotting. This is suitable for blood analysis.
- **Test Tube Containing Calcium Oxalate**: Calcium oxalate also acts as an anticoagulant by binding calcium ions, preventing clotting. This is suitable for blood analysis.

6. **Conclusion**: The test tube that should not be used for drawing blood for analysis is the one containing calcium bicarbonate, as it promotes clotting.

### Final Answer:
**You will not use the test tube containing calcium bicarbonate for the purpose of drawing blood for analysis of blood corpuscles and plasma.**

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