Science — AI-generated practice question

| Basis | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| (i) Presence of oxygen | Takes place in the presence of oxygen | Takes place in the absence of oxygen |
| (ii) Products formed | Carbon dioxide and water | Ethanol + CO₂ (in yeast) OR lactic acid (in muscle cells) |
| (iii) Energy released | Much greater amount of energy released | Less energy released |
| (iv) Location in cell | Cytoplasm (glycolysis) + Mitochondria (breakdown of pyruvate) | Cytoplasm only |

Organisms using anaerobic respiration: Yeast (fermentation), some bacteria, and human muscle cells (during sudden/intense activity).

Note: In both types, the first step — breakdown of glucose (6-carbon) into pyruvate (3-carbon) — occurs in the cytoplasm.

Source: Life Processes, Section 5.3 Respiration

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• Examiners award one mark per comparison point; the table format makes this clear and easy to mark.
• Mention both anaerobic products (ethanol/CO₂ for yeast AND lactic acid for muscles) — missing one costs a mark.
• Stating that aerobic respiration also begins in the cytoplasm (glycolysis) and continues in the mitochondria shows complete understanding.
• The textbook explicitly states "the release of energy in the aerobic process is a lot greater than in the anaerobic process" — use this language.
• Naming organisms that use anaerobic respiration (yeast, bacteria, muscle cells) is often asked as a follow-up; including it here covers Exercise Q.8.