BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Histidine is the only amino acid that give biuret test positive.

Detailed explanation-2: -1. During the Biuret testing, the samples that gave a positive result were albumin, casein, and gelatin. Biuret tests the presence of molecules that contain two or more peptide bonds. Albumin and casein and gelatin gave an intense purple color.

Detailed explanation-3: -Glycine and tyrosine will give negative test results because of the absence of peptide bonds, These are amino acids that make up proteins, however, single amino acids do not have peptide bonds. Gelatin, albumin, and casein are proteins made up of peptide bonds. These will give positive results (purple color).

Detailed explanation-4: -Only amino acid, Histidine, gives a positive result.

Detailed explanation-5: -As previously mentioned, if a sample is tested using the biuret reagent it will change to a purple color, if it contains protein. This is a positive biuret test result. Conversely, if the sample solution remains a light blue color, the protein concentration is low and considered a negative result.