What is the path of carbon dioxide as it leaves the lungs?
▶️ Answer/Explanation
Ans: A
Carbon dioxide follows this path when exhaled: starts in alveoli (gas exchange), moves to bronchioles (smaller tubes), then bronchi (larger tubes), and finally trachea (windpipe) before exiting. Option A correctly shows this sequence from smallest to largest airways.
The diagram shows the breathing system in humans. Which labelled part is surrounded by blood capillaries for gas exchange?
▶️ Answer/Explanation
Ans: D
Gas exchange occurs in the alveoli (labelled D), where oxygen diffuses into the blood and carbon dioxide diffuses out. These tiny air sacs are surrounded by a dense network of blood capillaries, maximizing surface area for efficient gas exchange.
Other labelled parts (A, B, C) represent structures like the trachea or bronchi, which transport air but lack capillary networks for gas exchange. Thus, the correct answer is D.