Gas exchange and respiration

Learning objectives

• Distinguish ventilation from respiration.
• Explain alveolar exchange adaptations.
• Compare aerobic and anaerobic respiration.

The big idea

Ventilation moves air into and out of lungs, gas exchange transfers gases across surfaces and respiration comprises reactions transferring energy within cells. Alveoli combine a large area with thin moist barriers and blood flow.

Aerobic respiration uses oxygen and produces carbon dioxide and water. Anaerobic pathways transfer less energy per glucose; muscles form lactate and yeast fermentation produces ethanol and carbon dioxide. Tobacco smoke can damage exchange and circulation.

Investigate and explain

Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.

No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.

Open the interactive investigation

Check your understanding