What type of tests are used to show if a specific enzyme or drug is present and conducting the expected reaction?

An activity assay is specifically designed to measure the presence and function of a particular enzyme or drug by assessing its ability to conduct a specific biochemical reaction. This type of assay provides quantitative information about the enzyme's activity under defined conditions, allowing researchers to determine if the enzyme is functional and how effectively it catalyzes the reaction.

In this context, the focus is on measuring the activity level, which directly correlates to the enzyme or drug's efficacy. By utilizing substrate concentrations, measuring the reaction rate, and employing specific conditions such as temperature and pH, activity assays can produce reliable data on how well the enzyme or drug performs its role in a biological or experimental system.

This contrasts with other options. A potency assay typically evaluates the strength of a drug, often focusing on its effect or response rather than the specific activity of an enzyme. The term assay itself is broad and could refer to various types of tests without specifying functionality. Chromatography, while an important analytical technique for separating components within a mixture, does not directly measure enzyme activity or the specific biochemical reaction carried out by the enzyme.

Thus, the activity assay stands out as the correct choice for accurately demonstrating whether a specific enzyme or drug is present and performing its expected reaction.