In aqueous acid or enzyme-catalyzed reactions, hydrolysis of a polymer proceeds by adding a molecule of which substance?

• A. Water
• B. Oxygen
• C. Nitrogen
• D. Methane

Answer: (A)

Hydrolysis is the breaking of bonds by adding water. In aqueous acid or enzyme-catalyzed hydrolysis, a water molecule attacks the bond in the polymer, leading to its cleavage and forming two smaller molecules. Water donates a hydrogen to one fragment and a hydroxyl group to the other, effectively splitting the polymer. The other substances listed (oxygen, nitrogen, methane) don’t participate as the adding reactant in hydrolysis under these conditions; they’re associated with other types of reactions, not the water-driven bond-breaking that defines hydrolysis.