Final answer:
Enzymes lower the activation energy needed for a chemical reaction to occur by bringing reactant molecules together and facilitating bond-breaking and bond-forming processes.
Step-by-step explanation:
Enzymes help facilitate chemical reactions by lowering the activation energy needed for the reaction to occur. They do this by binding to reactant molecules, bringing them together and contorting them in a way that facilitates bond-breaking and bond-forming processes. Enzymes are not consumed by the reactions they catalyze and they remain unchanged at the end of the reaction.