The major factor which could affect the binding of `CO_2` to Hb is

Options

A. Low temperature
B. `pO_2`
C. High pH
D. High temperature

Answer

To solve the question regarding the major factor that affects the binding of CO2 to hemoglobin (Hb), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hemoglobin Function**: Hemoglobin is a protein in red blood cells that carries oxygen (O2) from the lungs to the rest of the body and helps transport carbon dioxide (CO2) back to the lungs.

2. **Factors Affecting CO2 Binding**: Several factors can influence the binding of CO2 to hemoglobin, including temperature, pH, and the partial pressure of oxygen (pO2).

3. **Analyzing the Options**:
- **Lower Temperature**: Generally, lower temperatures can increase the affinity of hemoglobin for CO2, but this is not the major factor.
- **Pressure of O2**: The partial pressure of oxygen is crucial because high levels of O2 can reduce the ability of hemoglobin to bind CO2.
- **High pH**: An increase in pH (alkaline conditions) can also reduce CO2 binding, but it is not the primary factor.
- **High Temperature**: Higher temperatures can decrease the affinity of hemoglobin for CO2, but again, this is not the most significant factor.

4. **Identifying the Major Factor**: The most significant factor affecting the binding of CO2 to hemoglobin is the partial pressure of oxygen (pO2). When the pO2 is high (as in the lungs), hemoglobin prefers to bind to oxygen rather than carbon dioxide. This is known as the Haldane effect.

5. **Conclusion**: Therefore, the major factor that affects the binding of CO2 to hemoglobin is the **pressure of O2**.

### Final Answer:
The major factor which could affect the binding of CO2 to hemoglobin (Hb) is the **pressure of O2**.

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