IGCSE Biology
2026 - 2028
Syllabus Checklist
Topic 11: Gas Exchange in Humans
Gas Exchange in Humans
Describe the features of gas exchange surfaces
in humans, limited to:
▪ Large surface area
▪ Thin surface
▪ Good blood supply
▪ Good ventilation with air.
Identify in diagrams and images the following parts of the breathing system
:
lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli, and associated capillaries.
Investigate the differences in composition between inspired and expired air using limewater
as a test for carbon dioxide
.
Describe the differences in composition between inspired
and expired air
, limited to: oxygen, carbon dioxide, and water vapour.
Investigate and describe the effects of physical activity
on the rate
and depth of breathing
.
Explain the differences in composition between inspired and expired air.
Explain the link between physical activity
and the rate
and depth of breathing
in terms of:
▪ Increased carbon dioxide concentration in the blood
▪ Detection by the brain
▪ Increased rate and depth of breathing.
Explain the role of goblet cells
, mucus
, and ciliated cells
in protecting the breathing system from pathogens and particles.
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