Which explains the basis of the biuret test? a. under base conditions, copper ions bind to the amino groups of proteins and change color. b. iodine fits into the coils of starch polymers and changes color. c. a blue dye binds to protein and changes color. d. sudan iii dye binds to lipids and changes color.

A

Explanation:

In the Biuret test, the copper ions bind covalently to the amino groups as shown in the image to form a violet complex. This violet complex is responsible for the colour change as shown

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