Hello!
Chemical reactions require energy to begin. The reactants must collide with enough energy for bonds to change. This energy is known as activation energy - the difference in energy between that of the reactants and the amount needed for the reaction to occur.
Catalysts lower the activation energy needed for a chemical reaction to occur, therefore also increasing the rate of a reaction. Enzymes are proteins which act as catalysts within cells.
Therefore, enzymes cause the activation energy to lower.
Hope this helps!
