O-LevelBiologyRespiration5090/11 · May/June 2022 · Q181 Mark

Four flasks are sterilised and set up as shown. Which flask will show signs of fermentation (anaerobic respiration) after one hour? [Figure 18.1]

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AFlask A: Dried yeast and water in refrigerator (4°C)

BFlask B: Dried yeast and water in warm room (20°C)

CFlask C: Dried yeast, water and sugar in refrigerator (4°C)

DFlask D: Dried yeast, water and sugar in warm room (20°C)

✓ Correct answer

D: Flask D: Dried yeast, water and sugar in warm room (20°C)

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Topic: Respiration, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2022 Paper 1 Variant 1, question 18.

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