Which of the following steps not involved in respiration `:-`

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks us to identify which of the given options is not involved in the process of respiration.

2. **Analyzing the Options**:
- **Option 1: Diffusion of gases across alveolar membrane**: This is a crucial step in respiration where oxygen (O2) and carbon dioxide (CO2) are exchanged between the alveoli in the lungs and the blood. This step is definitely involved in respiration.

- **Option 2: Transport of gases by blood**: After the gases diffuse into the blood, they are transported throughout the body via the circulatory system. This is also an essential step in respiration.

- **Option 3: Provide nutrients to all the living cells of the body**: This option refers to the delivery of nutrients, which is primarily the role of the digestive system and not directly related to the respiratory process. Respiration primarily deals with the exchange and utilization of gases (O2 and CO2), not nutrients.

- **Option 4: Utilization of O2 by cells for catabolic reactions and resultant release of CO2**: This describes cellular respiration, where cells use oxygen for metabolic processes and produce carbon dioxide as a byproduct. This is a key step in respiration.

3. **Identifying the Correct Answer**: Based on the analysis, the option that is not involved in respiration is **"Provide nutrients to all the living cells of the body."**

### Conclusion:
The correct answer is **"Provide nutrients to all the living cells of the body."**

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