Science — AI-generated practice question

Structure of the Human Respiratory System:

Air enters through the nostrils, passes through the nasal cavity (where it is filtered and warmed), down the pharynx and larynx, into the trachea (windpipe). The trachea divides into two bronchi, one entering each lung. Inside the lungs, bronchi branch into smaller bronchioles, which end in tiny air sacs called alveoli.

Alveoli are the functional units of the lungs. They have:

• Extremely thin, moist walls
• Rich network of blood capillaries
• Large surface area (millions of alveoli)

Function:
Oxygen from inhaled air diffuses across the thin alveolar walls into the blood capillaries. Simultaneously, carbon dioxide from the blood diffuses into the alveoli and is expelled during exhalation. This process is called gaseous exchange. The diaphragm and rib muscles create breathing movements that ventilate the lungs, ensuring a continuous supply of fresh air to the alveoli.

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• Examiners expect you to cover both structure and function — name the organs in sequence (nostrils → alveoli) and then explain gaseous exchange.
• Key terms to include: alveoli, bronchi, bronchioles, trachea, diffusion, gaseous exchange, diaphragm.
• The alveolar features (thin walls, large surface area, capillary network) are high-value points — always mention all three.
• Avoid writing a long essay; structured points or short paragraphs score well for a 5-mark question.