GCSE Biology · Edexcel 1BI0 · Topic 8C
Respiration
Key points
- Cellular respiration is an exothermic reaction that releases energy from glucose for muscle contraction, building molecules and keeping warm.
- Aerobic: glucose + oxygen → carbon dioxide + water. It happens in mitochondria and releases a lot of energy.
- Anaerobic in animals: glucose → lactic acid. It releases much less energy. After exercise, extra oxygen is needed to break down the lactic acid (the oxygen debt).
- Anaerobic in plants and yeast: glucose → ethanol + carbon dioxide (fermentation).
- Core practical: measure respiration rate in small organisms with a respirometer; soda lime absorbs CO₂ so the coloured liquid moves as oxygen is used.
- During exercise heart rate and breathing rate rise to deliver more oxygen and glucose and remove CO₂.
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Respiration is the process in every living cell that releases energy from glucose. This sub-topic compares aerobic and anaerobic respiration, explains the oxygen debt after exercise and describes the core practical that measures respiration…
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