In lung, gaseous exchange is done by `:-`

Options

A. Simple diffusion
B. Active transport
C. Passive transport
D. fascilitated diffusion

Answer

**Step-by-Step Solution:**

1. **Understanding Gaseous Exchange in the Lungs:**
- The primary function of the lungs is to facilitate the exchange of gases, specifically oxygen (O2) and carbon dioxide (CO2).

2. **Identifying the Mechanism of Gaseous Exchange:**
- Gaseous exchange occurs due to differences in concentration levels of the gases in the alveoli (air sacs in the lungs) and the blood.

3. **Examining the Options:**
- **Simple Diffusion:** This is the process where molecules move from an area of higher concentration to an area of lower concentration without the need for energy.
- **Active Transport:** This process requires energy to move substances against their concentration gradient (from lower to higher concentration).
- **Passive Transport:** This is a broader category that includes simple diffusion and does not require energy.
- **Facilitated Diffusion:** This involves the use of specific proteins to help transport substances across the membrane, also from higher to lower concentration.

4. **Applying the Concept to Gaseous Exchange:**
- In the lungs, oxygen is present in higher concentration in the alveoli compared to the blood, which has a higher concentration of carbon dioxide. Therefore, oxygen diffuses into the blood, and carbon dioxide diffuses out into the alveoli.

5. **Conclusion:**
- The process of gaseous exchange in the lungs is primarily accomplished through **simple diffusion**, as it involves the movement of gases from areas of higher concentration to areas of lower concentration without the use of energy.

**Final Answer:**
In the lungs, gaseous exchange is done by **simple diffusion**.

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