Describe the human respiratory system with a labelled diagram. How are gases exchanged in the lungs?
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define in one line. Breathing takes air into the lungs, where oxygen enters the blood for respiration and carbon dioxide leaves.
2 · Trace the path of air. Nostrils (hairs and mucus filter air) → pharynx → larynx → trachea (rings of cartilage) → bronchi → bronchioles → alveoli.
3 · Explain breathing in. The ribs are lifted and the diaphragm flattens; the chest cavity grows and air rushes into the lungs.
4 · Explain gas exchange. Alveoli have thin walls and many capillaries. Oxygen diffuses into the blood and is carried by haemoglobin; CO₂ diffuses out and is breathed out.
5 · Draw the respiratory system. [Diagram: nasal passage, pharynx, larynx, trachea with rings of cartilage, bronchi, bronchioles, lungs, alveoli, ribs, diaphragm]
6 · Link to daily life. Smoke and dust harm the lungs, so avoiding smoking and wearing a mask in polluted air protect them.
7 · Close in one line. The large, thin, moist surface of the alveoli makes gas exchange fast.
Scoring tip: Draw the diagram first, then write the path of air as a flow chart. Show the rings of cartilage; examiners look for them.
