Effect of 2,3- DPG on the human blood is that `:-`

Options

A. It increases the affinity of `O_(2)` for haemoglobin
B. It decreases the affinity of `O_(2)` for haemoglobin
C. It increases association of Hb and `O_(2)`
D. It decreases the value of `P_(50)`

Answer

### Step-by-Step Solution:

1. **Understanding 2,3-DPG**:
- 2,3-Diphosphoglycerate (2,3-DPG) is a compound found in red blood cells that plays a crucial role in regulating oxygen binding to hemoglobin.

2. **Function of 2,3-DPG**:
- The primary function of 2,3-DPG is to modulate the affinity of hemoglobin for oxygen. It does this by binding to hemoglobin and stabilizing the deoxygenated form of hemoglobin, which promotes the release of oxygen.

3. **Impact on Oxygen Affinity**:
- When 2,3-DPG levels are high, the affinity of hemoglobin for oxygen decreases, facilitating oxygen release to tissues. Conversely, when 2,3-DPG levels are low, hemoglobin's affinity for oxygen increases, making it more difficult for oxygen to be released.

4. **Analyzing the Options**:
- **Option A**: "Increases the affinity of oxygen for hemoglobin." - This is incorrect because 2,3-DPG actually decreases the affinity.
- **Option B**: "Decreases the affinity of oxygen for hemoglobin." - This is correct; 2,3-DPG decreases the affinity, allowing for easier oxygen release.
- **Option C**: "Increases association of oxygen." - This is misleading; it does not increase the association but rather facilitates release.
- **Option D**: "Decreases the value of P50." - P50 is the partial pressure of oxygen at which hemoglobin is 50% saturated. A decrease in P50 indicates an increase in affinity, which is incorrect in the context of 2,3-DPG.

5. **Conclusion**:
- The correct effect of 2,3-DPG on human blood is that it **decreases the affinity of oxygen for hemoglobin**, facilitating oxygen release to tissues.

### Final Answer:
- The effect of 2,3-DPG on human blood is that it **decreases the affinity of oxygen for hemoglobin**.

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