`Hb + O_(2) underset((2))overset ((1))hArr HbO_(2)`
Select (1) and (2) from the given options

Options

A. (1) is tissues and (2) is lungs
B. (1) is lungs and (2) is blood
C. (1)is blood and (2) is lungs
D. (1) is lungs and (2) is tissues

Answer

To solve the question regarding the reaction of hemoglobin (Hb) with oxygen (O₂) and the identification of the locations of the reaction, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**: The reaction provided is:
\[ \text{Hb} + \text{O}_2 \underset{(2)}{\overset{(1)}{\rightleftharpoons}} \text{HbO}_2 \]
Here, Hb represents hemoglobin, O₂ is oxygen, and HbO₂ is oxyhemoglobin.

2. **Identifying the Reaction Locations**:
- **(1)**: This part of the reaction indicates where hemoglobin binds with oxygen to form oxyhemoglobin. This occurs in the **lungs**. The lungs are the site where oxygen is inhaled and diffuses into the blood, where it binds to hemoglobin.
- **(2)**: This part indicates where oxyhemoglobin dissociates back into hemoglobin and oxygen. This occurs in the **tissues**. The tissues utilize oxygen for cellular respiration, leading to the release of oxygen from hemoglobin.

3. **Final Answer**: Based on the above understanding:
- (1) corresponds to the **lungs**.
- (2) corresponds to the **tissues**.

### Summary of the Answer:
- **(1)**: Lungs
- **(2)**: Tissues