MODEL
Design a gas-exchange surface
Control area, thickness and gradient.
Model
Halve area and double thickness. Explain why the index becomes one quarter of baseline.
Diffusion index (baseline 100)100
Diffusion rate is proportional to area × gradient ÷ thickness when diffusion coefficient is fixed. Ventilation and perfusion help maintain the gas gradients.
Fick-style relative comparison, not an anatomical scale drawing or a prediction of total oxygen delivery.
Explain what you observed
How can you isolate the effect of one factor?
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Read a related learning guide →Practise Respiration →Open the student notes folder ↗Concepts and sources
Chapter extension: selected concepts, not complete syllabus coverage.
Read the supporting source ↗PMDC curriculum ↗Questions and explanations are original teaching material; these are not official exam questions.