A student is conducting an experiment in which he adds an inhibitor to an enzyme-catalyzed reaction that contains alkaline phosphatase. When the student first adds the inhibitor, the reaction rate decreases, however, he can return the reaction rate to normal by adding a large quantity of substrate. What type of inhibitor is the student using, non-competitive or competitive?

competitive

Explanation:

An inhibitor is a substance that hinders the action of an enzyme. An inhibitor may be competitive or non competitive.

A competitive inhibitor is an inhibitor that is very similar to the substrate hence it binds to the enzyme instead of the substrate. A noncompetitive inhibitor binds to a site that is different from the active site. This site is called an allosteric site.

If we look at the experiment described in the question, the reaction rate decreases upon addition of the inhibitor. This effect is reversed by adding a large quantity of substrate.

The implication of this observation is that the enzyme and the inhibitor compete for the active site on the substrate.

Hence the inhibitor is a competitive inhibitor.