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AS · Practice questions · The gas exchange system and its airways

Name the airway, then list its wall.

Six original Cambridge-style questions on the human gas exchange system, from the distribution of cartilage to why smokers cough.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Tell the airways apart

Cartilage first, then lining.

01
Recall
[3 marks]

Name, in order, the structures that air passes through from the trachea to the site of gas exchange.

  • Trachea, then a bronchus. ✓
  • Then bronchioles (branching into smaller bronchioles). ✓
  • Then the alveoli, where gas exchange with the capillary network occurs. ✓
02
Recall
[4 marks]

Describe the distribution of cartilage, goblet cells and smooth muscle in the trachea, bronchi and bronchioles.

  • Cartilage: C-shaped rings in the trachea, irregular plates in the bronchi, none in the bronchioles. ✓
  • Goblet cells: in the ciliated epithelium of the trachea and bronchi; few or none in bronchioles. ✓
  • Smooth muscle: in the walls of all three. ✓
  • It makes up a relatively larger proportion of the wall in the bronchioles. ✓
03
Explain
[4 marks]

Explain how goblet cells, mucous glands and ciliated epithelial cells work together to maintain the health of the gas exchange system.

  • Goblet cells and mucous glands secrete mucus onto the airway lining. ✓
  • The sticky mucus traps dust, pollen and pathogens such as bacteria in the inhaled air. ✓
  • Cilia beat in a coordinated way to move the mucus up to the throat, where it is swallowed. ✓
  • So particles and pathogens are removed before they reach the alveoli, reducing infection and keeping the exchange surface clean. ✓
04
Explain
[3 marks]

Suggest why people who smoke for many years often have a persistent cough and frequent chest infections.

  • Tobacco smoke paralyses and destroys cilia, so mucus is not moved up the airways. ✓
  • Smoke increases mucus secretion by goblet cells and mucous glands, so mucus builds up. ✓
  • Coughing is the only way to remove the mucus, and bacteria trapped in it multiply, causing infections such as bronchitis. ✓
05
Analysis
[3 marks]

A student looks at a slide of lung tissue and sees a tube with a lining of columnar ciliated cells, a ring of smooth muscle and no cartilage, surrounded by many thin-walled air spaces. Identify the tube and the air spaces and give the evidence for each.

  • The tube is a bronchiole. ✓
  • Evidence: no cartilage (so not trachea or bronchus) but a ciliated lining and smooth muscle. ✓
  • The air spaces are alveoli: thin walls of squamous epithelium. ✓
06
Data
[3 marks]

Describe the features you would include, and those you would leave out, when making a plan diagram of a transverse section of the trachea wall.

  • Include clear, continuous outlines of each tissue layer: ciliated epithelium, smooth muscle, the C-shaped cartilage and the lumen. ✓
  • Draw the layers in the correct relative proportions and label them. ✓
  • Do not draw individual cells and do not shade. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.