Advanced Placement (AP) Biology Practice Exam

In which scenario would hydrolysis occur?

1. When breaking down a protein into amino acids.

2. When forming a complex sugar from simple sugars.

3. When joining fatty acids to glycerol.

4. When digesting starch into glucose units.

The correct answer is: When digesting starch into glucose units.

Hydrolysis is a chemical reaction that involves the addition of water to break bonds within larger molecules, resulting in smaller molecules. It is commonly used in biological systems to degrade complex molecules during metabolic processes. In the context of the digestion of starch, hydrolysis occurs when enzymes break the glycosidic bonds between glucose units in the polysaccharide starch. This process results in the release of individual glucose molecules that can be easily absorbed by the body for energy. Enzymes like amylase are involved in this hydrolytic reaction during the digestive process. Other scenarios presented, such as forming complex sugars or joining fatty acids to glycerol, involve condensation reactions. In those cases, smaller molecules combine to form larger molecules while releasing water, which is the opposite of hydrolysis. Therefore, the digestion of starch into glucose units is the scenario that correctly illustrates hydrolysis.