Question

Gaseous exchange takes place in which part of the respiratory system?

• A. Bronchus
• B. Alveolus
• C. Pharynx
• D. Larynx

Hint:

Alveoli are called functional units of lungs because gaseous exchange occurs there.

Answer 1

The Correct Option is B

Concept:
The respiratory system helps in:
• Intake of oxygen
• Removal of carbon dioxide Actual gaseous exchange occurs in tiny air sacs of lungs called: \[ \boxed{\text{Alveoli}} \] Single air sac is called: \[ \text{Alveolus} \]

Step 1: Understand alveoli.
Alveoli are:
• Thin-walled
• Moist
• Richly supplied with blood capillaries These features help rapid diffusion of gases.

Step 2: Understand gaseous exchange.
Inside alveoli:
• Oxygen enters blood
• Carbon dioxide leaves blood Diffusion occurs because of concentration differences.

Step 3: Analyze options carefully.
Option (A): Bronchus
Air conducting passage. Incorrect. Option (B): Alveolus
Site of gaseous exchange. Correct. Option (C): Pharynx
Common passage for food and air. Incorrect. Option (D): Larynx
Voice box. Incorrect.

Step 4: Select the correct answer.
Therefore, gaseous exchange takes place in: \[ \boxed{\text{Alveolus}} \] Hence, \[ \boxed{(2)\ \text{Alveolus}} \]