Advanced Placement (AP) Biology Practice Exam

How does digestion function in relation to polymers?

1. It combines monomers to form larger structures.

2. It uses water to break down polymers into monomers.

3. It typically requires the absence of enzymes.

4. It involves the condensation of multiple polymers.

The correct answer is: It uses water to break down polymers into monomers.

Digestion involves breaking down complex molecules, known as polymers, into their simpler building blocks, called monomers. This process is essential for the body to utilize nutrients effectively. The correct answer highlights the role of water in this breakdown process; specifically, it utilizes a chemical reaction known as hydrolysis. During hydrolysis, water molecules are added to the polymer, breaking the bonds that hold the monomers together. This allows cells to absorb the resultant monomers for various biochemical functions, such as energy production and cellular repair. In contrast, combining monomers to form larger structures is a process called polymerization, which occurs in the body for growth and repair but is not part of digestion itself. The assertion that digestion requires the absence of enzymes is incorrect, as enzymes are crucial for facilitating the breakdown of polymers into monomers efficiently. Additionally, the idea that digestion involves the condensation of multiple polymers incorrectly describes a process that would lead to the formation of larger molecules rather than the breakdown necessary for digestion.