Which of the following steps not involved in respiration ?

Options

A. Diffusion of gass across alveolar membrane
B. Transport of gases by the blood
C. Provide nutrients and `O_(2)` to all the living cells of body
D. Utilization of `O_(2)` by the cells for catabolic reactions and resultant release of `CO_(2)`

Answer

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is a biological process where cells utilize oxygen to produce energy through catabolic reactions, resulting in the release of carbon dioxide (CO2).

2. **Identifying Steps Involved in Respiration**:
- The main steps of respiration include:
- **Diffusion of gases across the alveolar membrane**: This is where oxygen from the air enters the blood in the lungs.
- **Transport of gases by the blood**: Blood carries oxygen to cells and transports CO2 back to the lungs.
- **Utilization of oxygen by cells for catabolic reactions**: Cells use oxygen to produce energy, resulting in the release of CO2.

3. **Analyzing the Given Options**:
- **Option 1**: Diffusion of gas across alveolar membrane - This is involved in respiration.
- **Option 2**: Transport of gases by the blood - This is involved in respiration.
- **Option 3**: Provide nutrients and oxygen to all the living cells in the body - This is NOT involved in respiration because nutrients are part of the digestive system, not the respiratory system.
- **Option 4**: Utilization of oxygen by the cells for catabolic reactions and resultant release of CO2 - This is involved in respiration.

4. **Conclusion**:
- The step that is NOT involved in respiration is **Option 3: Provide nutrients and oxygen to all the living cells in the body**.

### Final Answer:
The step not involved in respiration is **providing nutrients and oxygen to all the living cells in the body**.

---