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Learning objective

Explain how to conduct tests for: (a) starch using iodine solution, (b) reducing sugars using Benedict’s solution, (c) proteins using the biuret test, and (d) fats and oils using the ethanol emulsion test.

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Cambridge IGCSE Combined ScienceBiological moleculesCore contentPractical objective

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Quick explanation

Explain how to conduct tests for: (a) starch using iodine solution, (b) reducing sugars using Benedict’s solution, (c) proteins using the biuret test, and (d) fats and oils using the ethanol emulsion test

  • This point belongs to Biological molecules, especially Biological molecules outcomes.
  • You need to be able to explain how to conduct tests for: (a) starch using iodine solution, (b) reducing sugars using Benedict’s solution, (c) proteins using the biuret test, and (d) fats and oils using the ethanol emulsion test.
  • The key ideas to know are Describe, Demonstrate, and Explain.
  • Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

DescribeDemonstrateExplain

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Paper 6 structured question: Biological molecules

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Method

Testing for Starch

To test for starch, follow these steps: 1. Take a small sample of the substance. 2. Add a few drops of iodine solution to the sample. 3. Observe any color change.

  1. a

    Describe the importance of using a control sample in this test.

    Aim for approximately 2 distinct marking points.

    [2]
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