A student cuts their finger during a sports lesson and notices the wound feels warm. Explain how anaerobic respiration in the muscle cells during exercise contributes to changes in the body, and describe one difference between anaerobic and aerobic respiration in animal cells.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
During intense exercise, muscle cells may not receive enough oxygen to meet their energy demands. They switch from aerobic respiration to anaerobic respiration. Cellular respiration is a continuously occurring chemical process that releases energy from the breakdown of organic compounds such as glucose.
Model answer (4 marks)
Anaerobic respiration occurs when oxygen supply is insufficient, so muscle cells use glucose without oxygen and produce lactic acid.
The production of lactic acid releases heat, which makes the wound feel warm.
Aerobic respiration requires oxygen and yields more energy from glucose than anaerobic respiration.
Thus, anaerobic respiration does not use oxygen, whereas aerobic respiration does.
The production of lactic acid releases heat, which makes the wound feel warm.
Aerobic respiration requires oxygen and yields more energy from glucose than anaerobic respiration.
Thus, anaerobic respiration does not use oxygen, whereas aerobic respiration does.
Examiner tips
- Use the word "anaerobic" and mention oxygen debt. Explain heat release as a result of lactic acid. State the key difference: oxygen requirement. Show the energy comparison briefly.
Common mistakes
- Confusing anaerobic with aerobic as the main energy source. Forgetting to mention heat or lactic acid. Mixing up which process uses oxygen.
Mark scheme (4 marks)
- Anaerobic respiration occurs when there is an insufficient/inadequate supply of oxygen (oxygen debt)
- Anaerobic respiration in animal cells produces lactic acid (from glucose)
- Aerobic respiration uses/requires oxygen whereas anaerobic respiration does not use oxygen
- Aerobic respiration releases more energy (from glucose) than anaerobic respiration
Key terms in this question
anaerobic respiration · aerobic respiration
Related
- Revision notes: Respiration →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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