Four Groups of Biological Molecules: Monomers, Chains and Identification Tests

Integrated ScienceChemical ReactionsAges 14–15

Choose a group of substances and watch monomers link together into a long chain: glucose molecules join to form starch, amino acids join into a protein chain via peptide bonds, glycerol combines with three fatty acids to form a fat, and ethylene polymerizes into polyethylene. On the right, a test tube shows identification tests: iodine solution turns starch blue-black, biuret reagent turns protein purple, and shaking fat with water leaves it floating as an undissolved layer. Raise the temperature above 70 °C to watch the protein chain unfold and coagulate – denaturation.