Respiration: Anaerobic Respiration
10.3 Anaerobic Respiration
Definition
- Breakdown of glucose without oxygen, releasing a small amount of energy.
- Occurs when oxygen supply is limited (e.g., vigorous exercise).
Word Equations
- In humans:
Glucose → Lactic acid + Energy - In yeast:
Glucose → Ethanol + Carbon dioxide + Energy
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Lactic Acid & Oxygen Debt
- Vigorous exercise → oxygen supply not enough → lactic acid builds up.
- Causes muscle fatigue and cramps.
- After exercise:
- Heart rate remains high to transport lactic acid to liver.
- Breathing rate remains high to supply extra oxygen.
- Extra oxygen breaks down lactic acid → repays “oxygen debt”.
Comparison: Aerobic vs Anaerobic
| Feature | Aerobic | Anaerobic |
|---|---|---|
| Oxygen used | Yes | No |
| Energy yield | High (≈38 ATP per glucose) | Low (≈2 ATP per glucose) |
| Products in humans | COâ‚‚ + Hâ‚‚O | Lactic acid |
| Products in yeast | COâ‚‚ + Hâ‚‚O | Ethanol + COâ‚‚ |
Applications
- Yeast anaerobic respiration → alcohol production (beer, wine), bread-making (CO₂ makes dough rise).
- Human anaerobic respiration → short bursts of intense activity.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course