I believe the term is "catalyst," though I'm not sure. I seem to remember that "enzyme" means the same thing in biological terms.
A factor in a scientific experiment that is subject to change is called a variable.
A variable.
Variables
A variable.
The factors which you change (vary) are called variables.
The part of an experiment that you test or manipulate change is called your independent variable.
In an experiment, factors that you change are called independent variables.
variables
changable factors
There are different types of factors that can change in an experiment. The environmental factors may change, and are out of your control. The variables in the experiment may also be changed but, are usually controlled by the individual conducting the experiment the majority of the time.
The variable that stays the same throughout the entire experiment is called the control.
The independent variable.