How do enzymes help an organism conserve energy?

Each chemical reaction has something called an activation energy. This means that a certain amount of energy is required for this reaction to occur. Let's hypothetically say Reaction A requires 400 J of energy to proceed. Enzymes, which are catalysts, dramatically lower this activation energy. Reaction A, if an enzyme is present, may now require only 150 J of energy to proceed. Thus, the organism can expend less energy to create chemical reactions.