Trace the path of air through the human respiratory system with a labelled diagram, and explain how the movements of the ribs and diaphragm make air flow in and out.

1. 1 · Define in one line. Breathing takes air into the lungs, where oxygen enters the blood and carbon dioxide leaves it.
2. 2 · Trace the path of air. Nostrils → nasal cavity → pharynx → glottis → trachea (rings of cartilage) → bronchi → bronchioles → alveoli.
3. 3 · Explain inhalation. The diaphragm contracts and flattens, and the ribs move up and out. Chest volume rises, pressure falls, and air rushes in.
4. 4 · Explain exhalation. The diaphragm relaxes into a dome, and the ribs move down and in. Chest volume falls, pressure rises, and air is pushed out.
5. 5 · Explain gas exchange. In the alveoli, oxygen diffuses into the capillaries and carbon dioxide diffuses out.
6. 6 · Draw the respiratory system. [Diagram: nostrils, nasal cavity, pharynx, larynx, trachea with cartilage rings, bronchi, bronchioles, lungs, alveoli, ribs, diaphragm]
7. 7 · Link to daily life. Smoke and dust harm the alveoli, so avoid smoking and cover your nose in dusty or smoky air.
8. 8 · Close in one line. So breathing works because a bigger chest means lower pressure, and air flows in.

Scoring tip: Label the diaphragm and the bronchioles clearly; examiners often ask for exactly these.