Describe how to test a sample of food for protein, starch and sugar - AQA - GCSE Biology Combined Science - Question 2 - 2021 - Paper 1
Question 2
Describe how to test a sample of food for protein, starch and sugar.
Give the colours that would be seen if the food sample contained protein, starch and sugar.
Worked Solution & Example Answer:Describe how to test a sample of food for protein, starch and sugar - AQA - GCSE Biology Combined Science - Question 2 - 2021 - Paper 1
Step 1
Protein Test
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Answer
To test for protein, grind up the food sample and add Biuret reagent (solution). If proteins are present, a purple or lilac color will develop.
Step 2
Starch Test
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Answer
For starch, add iodine solution to the food sample. A positive result is indicated by a color change to blue-black or dark blue.
Step 3
Sugar Test
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Answer
To test for sugar, grind up the food again and add Benedict's reagent (solution), then heat it. If sugar is present, the color changes to brick red, orange, brown, green, or yellow depending on the concentration.
