The feature of an experiment that is changed from one treatment to the next is referred to as a(n):

Variable

Explanation:

In the environment observed phenomena can be linked to a given set of possible outcomes. Thus, a variable can be understood as any quantity, quality or magnitude of a characteristic that can have several numerical values.

A variable can be understood as a classification or a measure; an amount that changes in each case or unit of study. A property in the study object that can be measured and enumerated, so the feature of an experiment that changes from one treatment to the next is called a variable.

bradykinin is a physiologically and pharmacologically active peptide of the kinin group of proteins, consisting of nine amino acids.