AP Biologyeasymcq1 pt

Adding an enzyme to a mixture speeds a reaction dramatically yet leaves its equilibrium position untouched. Which statement explains both observations?

A.The enzyme donates its own free energy, converting an unfavorable reaction into a favorable one
B.The enzyme lowers the activation energy of the transition state equally for forward and reverse directions, changing rate but not free energy change
C.The enzyme raises the energy of the products, pulling the reaction toward completion
D.The enzyme steadily consumes substrate until only product remains in the vessel

Explanation

Core Concept

A catalyst stabilizes the transition state, shrinking the barrier reactants must climb. It lowers this barrier identically for the forward and reverse reactions, so both directions accelerate proportionally. Because the starting and ending energy levels never move, the free energy change and the equilibrium constant stay fixed, and the system simply reaches its familiar balance point sooner.

Correct Answer

BThe enzyme lowers the activation energy of the transition state equally for forward and reverse directions, changing rate but not free energy change

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