Pepsin, a common enzyme found in the stomach, is most active at pH values between 0.5 and 2.5. It works slowly between pH values of 2.6 and 3.4. Beyond a pH of about 3.5, it becomes completely inactive. Why does this happen?

a. The enzyme inactivates because it melts into a liquid when it is not at the right pH.
b. pH changes also affect temperature, and that affects the reaction.
c. Because a pH of 3.5 is an acid and eats away at the enzyme.
d. The change in pH affects the shape and function of the enzyme. It can only function properly in its optimal pH range.

Question

Pepsin, a common enzyme found in the stomach, is most active at pH values between 0.5 and 2.5. It works slowly between pH values of 2.6 and 3.4. Beyond a pH of about 3.5, it becomes completely inactive. Why does this happen?

a. The enzyme inactivates because it melts into a liquid when it is not at the right pH.
b. pH changes also affect temperature, and that affects the reaction.
c. Because a pH of 3.5 is an acid and eats away at the enzyme.
d. The change in pH affects the shape and function of the enzyme. It can only function properly in its optimal pH range.

blues · Answer

Use process of elimination on multiple choice questions - focus on which ones you know it isn't. For example, pH and temperature are completely unrelated. So you know option b is not the correct answer...