What this practice covers
These questions are drawn from past CIE 0654 Co-ordinated Sciences papers and filtered to gas exchange in humans. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on gas exchange in humans, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Putting the trachea before the larynx, or bronchioles before bronchi.
- Saying expired air contains no oxygen.
- Saying inspired air is dry and expired air is moist. Inspired air is variable; expired air is saturated.
- Saying nitrogen is used up in the lungs.
- Saying cilia make mucus, or that goblet cells sweep it away.
- Saying cilia move mucus down into the lungs.
- Saying alveoli walls are thin "so the gases can get through", instead of saying the diffusion distance is short.
- Leaving the blood supply out of the list of alveolar adaptations.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Gas exchange in humans revision notes.