O Levels Biology (5090)•5090/12/M/J/18
Explanation
Anaerobic respiration in yeast produces alcohol and CO2
Steps:
- Recall that anaerobic respiration in yeast is alcoholic fermentation, lacking oxygen.
- Identify the glucose breakdown: C6H12O6 → 2C2H5OH + 2CO2 + energy.
- Note yeast converts pyruvate to ethanol and releases CO2, unlike animal cells.
- Match products to options, confirming alcohol (ethanol) and carbon dioxide.
Why A is correct:
- Alcoholic fermentation equation shows yeast produces ethanol (alcohol) and CO2 from glucose under anaerobic conditions.
Why the others are wrong:
- B: Lactic acid is produced in animal muscle cells, not yeast.
- C: Water is from aerobic respiration, not anaerobic in yeast.
- D: Lactic acid is absent; yeast makes alcohol, not just lactic acid.
Final answer: A
Topic: Anaerobic respiration
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