What is the last step involved in respiration?

Options

A. Diffusion of gases
B. Breathing
C. Utilisation of `O_(2)` by body cells and resultant
release of `CO_(2)`
D. Transport of gases

Answer

**Step-by-Step Solution:**

1. **Understanding Respiration**: Respiration is a multi-step process that involves several key stages: breathing, gas exchange, transport of gases, and utilization of gases by cells.

2. **Breathing**: The first step in respiration is breathing, which includes inhalation (taking in oxygen) and exhalation (releasing carbon dioxide). This process occurs in the lungs.

3. **Diffusion of Gases**: After breathing, the inhaled oxygen diffuses across the alveolar membrane in the lungs into the bloodstream. Simultaneously, carbon dioxide diffuses from the blood into the alveoli to be exhaled.

4. **Transport of Gases**: Once the oxygen is in the blood, it is transported by red blood cells to various body tissues. This transport is crucial for delivering oxygen where it is needed.

5. **Diffusion at the Tissue Level**: Upon reaching the tissues, oxygen diffuses from the blood into the body cells, while carbon dioxide produced by cellular metabolism diffuses from the cells into the blood.

6. **Utilization of Oxygen**: The final step in respiration is the utilization of oxygen by body cells for metabolic processes. During these processes, cells produce energy and release carbon dioxide as a waste product.

7. **Conclusion**: Therefore, the last step involved in respiration is the utilization of oxygen by body cells and the resultant release of carbon dioxide.

**Final Answer**: The last step involved in respiration is the utilization of oxygen by body cells and the resultant release of carbon dioxide.

---