Knowledge Organiser: Respiration
Key Terms
- Aerobic respiration — uses oxygen, high ATP yield
- Anaerobic respiration — no oxygen, low ATP yield
- Mitochondria — site of aerobic respiration
- Lactic acid — product of animal anaerobic respiration
- Fermentation — yeast/plant anaerobic respiration
- Ethanol — alcohol product of fermentation
- Oxygen debt — extra O2 needed post-exercise
- Exothermic — releases energy as heat
Must-Know Facts
- Aerobic: glucose + O2 → CO2 + H2O (+ energy)
- Anaerobic (animals): glucose → lactic acid
- Anaerobic (yeast): glucose → ethanol + CO2
- Aerobic yields ~36-38 ATP; anaerobic yields only 2 ATP
- Respiration is exothermic (releases heat)
- All living organisms respire continuously
- Lactic acid is cleared in the liver using extra oxygen
- Mitochondria are most numerous in high-energy cells
Common Marks Lost
- Confusing respiration with breathing
- Saying anaerobic respiration in muscles produces CO2 (it produces lactic acid)
- Not mentioning the liver in oxygen debt answers
- Confusing exothermic (respiration) with endothermic (photosynthesis)
- Not comparing ATP yields when asked to compare aerobic and anaerobic
- Saying only animals respire (all living things do)
Memory Aid
- A — Anaerobic respiration during exercise produces lactic acid
- L — Lactic acid builds up in muscles (fatigue and pain)
- C — Continued heavy breathing after exercise (the "debt")
- E — Extra oxygen oxidises lactic acid in the liver back to CO2 and H2O