A-LevelBiologyBiological moleculesMay/June 2023Paper 1 Q71 Mark
Which set of steps is the best method for conducting the emulsion test for lipids?
AAdd 2 cm³ of water to the sample.
Pour the water into a test-tube containing 2 cm³ of ethanol.
Lipids are present if the mixture becomes cloudy.
BAdd 2 cm³ of ethanol to the sample and shake.
Pour the ethanol into a test-tube containing 2 cm³ of water and boil.
Lipids are present if the mixture becomes clear.
CAdd 2 cm³ of water to the sample and shake.
Pour the water into a test-tube containing 2 cm³ of ethanol and boil.
Lipids are present if the mixture becomes cloudy.
DAdd 2 cm³ of ethanol to the sample and shake.
Pour the ethanol into a test-tube containing 2cm³ of water and shake again.
Lipids are present if the mixture becomes cloudy.
✓ Correct Answer
The correct answer is D. This question tests the candidate's understanding of biological molecules within the Biologysyllabus. The examiner's mark scheme requires...
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Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
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