Answer the following question given this paragraph: 

An enzyme is a protein that acts as a biological catalyst. Recall that a catalyst is a substance that increases the rate of a chemical reaction without itself being consumed in the reaction. Cellular processes consist of many chemical reactions that must occur quickly in order for the cell to function properly. Enzymes catalyze most of the chemical reactions that occur in a cell. A substrate is the molecule or molecules on which the enzyme acts. In the urease catalyzed reaction above, urea is the substrate. The Figure below diagrams a typical enzymatic reaction.


Q: What term is used to describe a protein that acts as a biological catalyst?


A:
enzyme