Question

a substance that influences the reaction but does not participate in the reaction is a catalyst reactant product substrate

Explanation:

A catalyst is a substance that influences the reaction rate by lowering the activation energy. It is not consumed in the reaction, meaning it does not participate in the reaction in a way that gets used up. A reactant is consumed in the reaction, a product is formed from the reaction, and a substrate is a substance on which an enzyme acts (in biochemical reactions, and this is a more specific term compared to the general reaction context here).

Answer:

catalyst