Which statements are correct for oxyhaemoglobin dissociation curve ?
(A) This curve is sigmoid
(B) When `CO_(2)` concentration increases, then this curve shifts towards right side
(C) Low temperature is favourable for dissociation of oxygen grom oxyhaemoglobin
(D) Binding of oxygen with haemoglobin is primarily related to partial pressure of `O_(2)`

Options

A. ABC are correct
B. ABD are correct
C. Only A is corrct
D. BCD are correct

Answer

To determine which statements are correct regarding the oxyhemoglobin dissociation curve, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding the Oxyhemoglobin Dissociation Curve**:
- The oxyhemoglobin dissociation curve represents the relationship between the partial pressure of oxygen (pO2) and the percentage saturation of hemoglobin with oxygen. The curve is typically S-shaped, also known as a sigmoid curve.

2. **Analyzing Statement (A)**:
- **Statement (A)**: "This curve is sigmoid."
- **Analysis**: The oxyhemoglobin dissociation curve is indeed sigmoid in shape. This is because at low pO2, hemoglobin binds oxygen slowly, then more rapidly at moderate pO2, and finally levels off at high pO2.
- **Conclusion**: This statement is **correct**.

3. **Analyzing Statement (B)**:
- **Statement (B)**: "When CO2 concentration increases, then this curve shifts towards the right side."
- **Analysis**: An increase in CO2 concentration (or a decrease in pH) causes the curve to shift to the right. This phenomenon is known as the Bohr effect, which indicates that hemoglobin releases oxygen more readily at higher CO2 levels.
- **Conclusion**: This statement is **correct**.

4. **Analyzing Statement (C)**:
- **Statement (C)**: "Low temperature is favorable for dissociation of oxygen from oxyhemoglobin."
- **Analysis**: Low temperature actually favors the association of oxygen with hemoglobin, not dissociation. Higher temperatures promote the release of oxygen from hemoglobin.
- **Conclusion**: This statement is **incorrect**.

5. **Analyzing Statement (D)**:
- **Statement (D)**: "Binding of oxygen with hemoglobin is primarily related to partial pressure of O2."
- **Analysis**: The binding of oxygen to hemoglobin is indeed primarily influenced by the partial pressure of oxygen. Higher pO2 leads to higher saturation of hemoglobin with oxygen.
- **Conclusion**: This statement is **correct**.

### Final Conclusion:
The correct statements regarding the oxyhemoglobin dissociation curve are:
- (A) This curve is sigmoid.
- (B) When CO2 concentration increases, then this curve shifts towards the right side.
- (D) Binding of oxygen with hemoglobin is primarily related to partial pressure of O2.

Thus, the correct options are A, B, and D.