The Biuret test is used to detect peptide bonds. It requires at least two peptide bonds to produce a positive result (a purple color change). Glycine, being the smallest amino acid, doesn't have any peptide bonds *within* its structure. Therefore, a solution of *only* glycine will not give a positive Biuret test. A solution of a *peptide* or *protein* containing glycine will, however, give a positive result because of the peptide bonds between amino acids *in the peptide or protein*.