IGCSE Biology glossary
Anaerobic respiration
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
The chemical reactions in cells that break down glucose without oxygen, releasing much less energy than aerobic respiration. In muscles: glucose → lactic acid. In yeast: glucose → alcohol + carbon dioxide.
What to include in an exam answer
Know both equations and the comparison: less energy released per glucose than aerobic. 'Oxygen debt' (lactic acid removal after exercise) is a favourite Extended question.
Example in context
Explaining muscle fatigue in a sprint: 'When oxygen runs short, the muscles respire anaerobically, breaking glucose into lactic acid and releasing a small amount of energy.'
Related syllabus topic
Respiration