A student performed the biuret test on a sample of red peas soup from a Jamaican school canteen. The solution changed from blue to purple. Which bond in the nutrient caused this colour change?

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Question

A student performed the biuret test on a sample of red peas soup from a Jamaican school canteen. The solution changed from blue to purple. Which bond in the nutrient caused this colour change?

Accepted Answer

Peptide bond — Award 1 mark for identifying that the biuret test detects peptide bonds present in proteins. A is incorrect — glycosidic bonds link monosaccharides in carbohydrates. C is incorrect — ester bonds are found in lipids. D is incorrect — hydrogen bonds are weak bonds not specifically detected by biuret reagent.

Answer

Ester bond

Answer

Glycosidic bond

Answer

Peptide bond

Answer

Hydrogen bond

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