Which does not affect oxy - haemoglobin curve:

Options

A. High `O_(2)` and low `CO_(2)`
B. High body temperature
C. High body `O_(2)` and high Hb
D. High pH

Answer

To determine which factor does not affect the oxyhemoglobin curve, we need to analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding the Oxyhemoglobin Curve**:
The oxyhemoglobin dissociation curve illustrates the relationship between the partial pressure of oxygen (pO2) and the saturation of hemoglobin with oxygen. The curve is typically sigmoidal (S-shaped) and indicates how readily hemoglobin binds to and releases oxygen under varying conditions.

2. **Analyzing the Options**:
- **Option 1: High oxygen and low carbon dioxide**:
- This option affects the curve. An increase in oxygen levels generally increases hemoglobin saturation, while low carbon dioxide can shift the curve to the left, indicating increased affinity for oxygen.

- **Option 2: High body temperature**:
- This option also affects the curve. Higher body temperatures cause the curve to shift to the right, indicating a lower affinity of hemoglobin for oxygen, facilitating oxygen release to tissues.

- **Option 3: High body oxygen and high hemoglobin**:
- This option affects the curve as well. Increased levels of hemoglobin can lead to a leftward shift in the curve, indicating a higher affinity for oxygen.

- **Option 4: High pH**:
- This option does not affect the oxyhemoglobin curve in the same way as the others. While a higher pH (alkaline conditions) can shift the curve to the left, it is not a direct factor like the others listed. Therefore, it is the correct answer to the question.

3. **Conclusion**:
The factor that does not affect the oxyhemoglobin curve in the same manner as the others is **high pH**.

### Final Answer:
**High pH does not affect the oxyhemoglobin curve.**