Final answer:
A molecule that increases the rate of an enzyme reaction is termed an activator, as it enhances enzyme activity, whereas an inhibitor binds to an enzyme to decrease its activity.
Step-by-step explanation:
The molecule that has the effect of increasing the rate of an enzyme reaction is known as a(n) activator. An activator increases the activity of specific enzymes by binding to the enzyme and enhancing its ability to bind to the substrate, thereby increasing the catalytic rate of the reaction. In contrast, an inhibitor is a molecule that interferes with enzyme function, often by binding to an enzyme and decreasing its affinity for the substrate or by directly blocking the active site, thus reducing or stopping the chemical reaction that the enzyme catalyzes. Inhibitors can either be competitive, binding to the active site in place of the substrate, or allosteric, binding to a different site on the enzyme and inducing a conformational change that affects the active site.