Breathing, Respiration and Gas Exchange — Revision notes

What this lesson covers

• Describe what air is made of and explain why nitrogen plays no part in breathing
• Define breathing and describe how air moves in and out of the lungs
• Explain what gas exchange is and where in the body it happens
• Explain what cellular respiration is and why it happens in mitochondria
• Compare breathing, gas exchange and respiration and say where each takes place
• Explain how exhaled air differs from inhaled air, and why rescue breaths work

Test yourself

Cover the answer, say it out loud, then check the full quiz on the lesson page.

• Which gas makes up most of the air you breathe in?
• Which of these does NOT happen during gas exchange?
• A candle burns out faster in exhaled air. Why?