Answer:Answer: Under base conditions, copper ions bind to amino groups of proteins and change colour.
Explanation: Biuret test is a general test for detecting the presence of a peptide bond in a compound. It is a test for proteins. Amino acids are joined together in proteins by peptide bonds. Copper ions from blue alkaline solution of CuSO4 react with amino groups of proteins to give a violet colored complex called a biuret compound