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IB Biology SL B3.1 Gas Exchange Questions

Practise IB Biology SL B3.1 by applying diffusion, ventilation, concentration gradients, oxygen transport and transpiration to exam questions.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • link surface area, diffusion distance, permeability and moisture to efficient gas exchange
  • explain how ventilation and blood flow maintain oxygen and carbon-dioxide gradients
  • interpret spirometry and pressure-volume changes during inspiration and expiration
  • explain stomatal control, leaf adaptations and environmental effects on transpiration

Covered syllabus points

B3.1.1—Gas exchange as vital functionB3.1.2—Properties of gas-exchange surfacesB3.1.3—Maintaining concentration gradientsB3.1.4—Mammalian lung adaptationsB3.1.5—Lung ventilationB3.1.6—Lung volume measurementsB3.1.7—Leaf gas exchange adaptationsB3.1.8—Leaf tissue distributionB3.1.9—TranspirationB3.1.10—Stomatal density

Learn this topic

Study B3.1 Gas exchange conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

Question 1

[Maximum number: 3]

Outline the process of gas exchange necessary for aerobic respiration in a unicellular eukaryotic organism.

Question 2

[Maximum number: 1]

Emphysema is a condition where the alveoli of the lungs are destroyed, resulting in patients feeling out of breath. The micrograph shows air pockets resulting from emphysema.

Figure for Question 2 — IB Biology SL

What is a direct consequence of the destruction of alveoli?

A

Decrease in surface area for gas exchange

B

Increased blood flow to the lungs

C

Increase in pulmonary surfactant production

D

Decrease in ventilation rate

Question 3

[Maximum number: 4]

Compounds of carbon, hydrogen and oxygen are used to supply and store energy.

Describe how a concentration gradient of oxygen is maintained between the lungs and blood capillaries.

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