Advanced Placement (AP) Biology Practice Exam

What factor can lead to the denaturation of an enzyme?

1. Decreased temperature

2. Increased pH

3. High substrate concentration

4. Extreme environmental temperature

The correct answer is: Extreme environmental temperature

Denaturation of an enzyme refers to the structural alteration that results in the loss of its biological activity, often due to changes in the environment. Extreme environmental temperatures, whether very high or very low, can significantly affect the stability of an enzyme. When temperatures become excessively high, the kinetic energy of molecules increases, which can disrupt the interactions that maintain the enzyme's three-dimensional structure. This can lead to the unfolding of the polypeptide chains, rendering the enzyme inactive. Environmental temperatures that are too low can also affect enzyme activity, but they do not typically cause denaturation; rather, they slow down molecular movement, which decreases reaction rates. Therefore, extreme high temperatures are primarily associated with the denaturation process, making this factor crucial in understanding enzyme functionality.