In which part of the respiratory system does the exchange of gases take place?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Alveoli
The alveoli are tiny balloon-like air sacs at the ends of the finest air tubes in the lungs. Their thin walls are covered with a network of blood capillaries, so oxygen passes from the air into the blood and carbon dioxide passes from the blood into the air here.
Why the other options are incorrect
Option (1) Pharynx — Incorrect. The throat, a common passage for air and food behind the nose and mouth.
Option (2) Oesophagus — Incorrect. The food pipe, a part of the digestive system, not the respiratory system.
Option (4) Trachea — Incorrect. The windpipe, which only carries air to and from the lungs.