IGCSE biology notes on gas exchange should explain alveolus adaptations and the ribcage/diaphragm changes during inspiration and expiration.

Hub: IGCSE biology notes · Gas exchange exam tips · Respiration notes.

Note essentials

Topic	Write in notes
Alveoli	Thin wall, moist, large surface area, good blood supply
Breathing	Intercostal muscles + diaphragm — pressure changes
Air composition	% O₂ and CO₂ inhaled vs exhaled
Link	Gas exchange ≠ cellular respiration (definitions)

Diagram

Side view of thorax — label before exam season.

Frequently asked questions

Smoking and gas exchange?

Add short bullet on tar/cilia if on your syllabus section.

Asthma in exams?

Often application — keep example in notes from past paper.

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