Why will the enzyme sucrase only act on sucrose and not bind to other disaccharides, such as maltose?

Answer: Because of its specificity.

Sucrase is an enzyme that catalyzes the hydrolysis of sucrose to glucose and fructose.

Explanation:

Enzymes are substances that catalyze biological reactions. Enzymes are specific that is they have the ability to bind with a selected substrate to catalyze a particular reaction. They have active sites which are specifically made for the binding of a particular substrate to elicit catalysis. Sucrose is a disaccharide made up of a glucose and fructose joined together while maltose is a disaccharide made up of two glucose molecules. Therefore, maltose will not be able to bind to the active site of sucrase due to its structure.