In hydrolysis, enzymes break down large molecules by adding which molecule?

• A. Oxygen
• B. Sugar
• C. Water
• D. Heat

Answer: (C)

Hydrolysis involves breaking chemical bonds by adding a water molecule. Enzymes that catalyze hydrolysis deliver water to the bond and split the substrate into smaller parts, so water is the molecule that gets added. That’s why water is the correct choice. Oxygen isn’t added to perform hydrolysis—it's more about oxidation or other processes. Sugar is typically a product formed after the bond is cleaved, not the molecule that drives the break. Heat can speed up reactions but isn’t the reactant being added in hydrolysis. For example, digestive enzymes break down starch, proteins, and fats by incorporating water to yield smaller sugars, amino acids, glycerol, and fatty acids.