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JEE Main · 2010 · 11 Apr 2010 · Offline · Biomolecules

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Biuret test is not given by
  1. (A)carbohydrates✓ Correct
  2. (B)polypeptides
  3. (C)urea
  4. (D)proteins

Answer: (A)

Solution

The biuret test responds to two or more peptide (amide) linkages lying close together, turning violet. Proteins and polypeptides are chains of such linkages and give the test, and urea, though a small molecule, carries amide groups and also responds. Carbohydrates are polyhydroxy aldehydes or ketones with no peptide or amide linkage at all, so they do not give the biuret test.

JEE Main · 2010 · 11 Apr 2010 · Offline · Single correct option

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