Energy Yield: Aerobic & Anaerobic Respiration (Cambridge International A-Level Biology)
Exam board Cambridge International · A-LevelUpdated 2026-06-30
Energy Yield: Aerobic and Anaerobic Respiration
Aerobic & anaerobic respiration
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There is a much greater energy yield from respiration in aerobic conditions than in anaerobic conditions
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In anaerobic respiration, glucose is only partially oxidised meaning only some of its chemical potential energy is released and transferred to ATP
- The only ATP-producing reaction that continues is glycolysis (~2 ATP)
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As there is no oxygen to act as the final electron acceptor, none of the reactions within the mitochondria can take place
- The stages that take place inside the mitochondria produce much more ATP than glycolysis alone (~36 ATP)
| Aerobic respiration | Anaerobic respiration | |
|---|---|---|
| Stages | Glycolysis Link reaction Krebs cycle Oxidative phosphorylation | Glycolysis Fermentation |
| Oxidation of glucose | Complete | Incomplete |
| Total ATP produced | High (≈36) | Low (2) |
| Location | Cytoplasm and mitochondria | Cytoplasm |
| Products | CO2, H2O | Yeast: CO2, ethanol Mammals: Lactate |
Exam Hint You won’t be expected to know the total yield of ATP from each stage of respiration in detail but be prepared to explain why aerobic respiration produces substantially more ATP than anaerobic respiration.
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