The protein molecules in many foods provide the amino acids required for cells to produce new proteins. To determine whether a sample contains protein, Biuret solution is used. Biuret solution contains copper ions. In the absence of proteins, it is blue in color. However, when proteins are present, the chemical state of the copper ion causes them to form a chemical complex with the pep tide bonds between amino acids, changing the color of the solution. In the presence of short peptides, the solution will turn pink, and in the presence of long polypeptides, the solution will turn violet.

Record your hypothesis about what will happen when Biuret solution is mixed with the solutions from test tubes 1, 2, 3, and 4 here. Be sure to use scientific reasoning to support your hypothesis..