Edexcel IGCSE Biology · Spec 2.50
Exercise and Breathing
Required practical: how exercise affects breathing rate, why muscles need more oxygen, and the oxygen debt.
Biology revision video
Exercise and Breathing
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Spec 2.50
What you need to know
- Measure breathing rate before and after exercise
- Present the results clearly
- Explain why the breathing rate changes
Active recall
Quick check
Answer each question before opening the answer.
How and why do breathing rate and depth change during exercise?
They increase, to supply more oxygen to muscles and remove the extra carbon dioxide produced by faster respiration.
Why does an oxygen debt build up during hard exercise?
Muscles respire anaerobically, producing lactic acid; oxygen is later needed to break it down.
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