Respiration is a physical process and depends upon the principle of diffusion .

Answer

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is often misunderstood as just a physical process. However, it encompasses both physical and chemical aspects. The primary function of respiration is to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.

2. **Chemical Process of Respiration**:
- The overall process of respiration can be summarized by the equation:
\[ \text{Glucose (C}_6\text{H}_{12}\text{O}_6\text{) + Oxygen (O}_2\text{) } \rightarrow \text{ Carbon Dioxide (CO}_2\text{) + Water (H}_2\text{O) + Energy (ATP)} \]
- This shows that respiration is indeed a chemical process because it involves the transformation of glucose and oxygen into carbon dioxide, water, and energy.

3. **Role of Diffusion in Respiration**:
- The principle of diffusion plays a crucial role in the respiratory process. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.
- In the lungs, oxygen concentration is higher in the alveoli compared to the blood. Therefore, oxygen diffuses from the alveoli into the blood.
- Conversely, carbon dioxide is present in higher concentration in the blood than in the alveoli, so it diffuses from the blood into the alveoli to be exhaled.

4. **Conclusion**:
- While respiration involves diffusion, it is primarily a chemical process. The statement that "respiration is a physical process and depends upon the principle of diffusion" is misleading because it simplifies the complexity of respiration.

### Final Statement:
Respiration is a chemical process that involves the exchange of gases, and while it relies on the principle of diffusion for gas exchange, it cannot be classified solely as a physical process.

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