Question

which of the following statements about enzyme - catalyzed reactions is true?
the free - energy change of the reaction is greater than when the same reaction occurs in the absence of an enzyme.
the rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.
the activation energy required for the reaction to proceed is greater than when the same reaction occurs in the absence of an enzyme.
energy from atp is required to activate the enzyme before it can catalyze the reaction.

Explanation:

Enzymes are biological catalysts. Catalysts increase the rate of a reaction by lowering the activation energy. The free - energy change ($\Delta G$) of a reaction is determined by the difference in free - energy between reactants and products and is not affected by the presence of an enzyme. Enzymes lower the activation energy, so the activation energy required for the reaction to proceed is less than when the reaction occurs without an enzyme. Also, not all enzymes require ATP for activation.

Answer:

The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.