<prompt> Biuret reaction is specific forCONH-linkagesCSNH2 groupNHNH2 groupAll of these  <response>: Biuret Reaction : Cupric ions in an alkaline medium form a violet color with peptide bond nitrogen Schiff, 1896. This needs a minimum of two peptide bonds, and so individual amino acids and dipeptides will not answer this test.Reference: Vasudevan 7th ed, pg 31 