SAT Subject Biology Practice Question 20: Answer and Explanation

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Question: 20

1. As a reaction proceeds, reactants form a transition state, which then forms the products. An enzyme affects the energy of the

A. products only
B. reactants only
C. transition state only
D. products and reactants
E. transition state and products

Correct Answer: C


An enzyme speeds up the rate of a reaction by lowering the activation energy, making the transition state less stable. It does not affect the energy of the products or the reactants.

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