`"_____________"` are the sites of gaseous exchange in lungs.

Answer

To answer the question, "_____________" are the sites of gaseous exchange in lungs, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question is asking for the specific structures in the lungs that facilitate the exchange of gases.

2. **Define Respiration and Breathing**:
- Respiration is the process of breaking down food to release energy, which also produces carbon dioxide (CO2) as a waste product.
- Breathing refers to the physical process of inhaling and exhaling, which is part of the overall respiration process.

3. **Identify the Structures in the Lungs**:
- In the lungs, there are millions of tiny structures that resemble bags or sacs. These structures are crucial for the exchange of gases.

4. **Name the Structures**:
- The bag or sac-like structures in the lungs are called **alveoli**.

5. **Explain the Function of Alveoli**:
- Alveoli increase the surface area available for gas exchange, allowing for efficient transfer of oxygen into the blood and removal of carbon dioxide from the blood.

6. **Location of Alveoli**:
- Alveoli are located at the terminal regions of the lungs, where they are grouped together to form clusters.

### Final Answer:
**Alveoli** are the sites of gaseous exchange in lungs.

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