Which of the following statements about enzymes is true?
Multiple Choice
Enzymes lower the energy of the transition state for the rate-determining step.
Enzymes Increase the activation energy for a reaction.
Enzymes shift the equilibrium to favor the product.
Enzymes decrease the equlilibrium constant.
The correct answer and explanation is:
The correct answer is:
Enzymes lower the energy of the transition state for the rate-determining step.
Explanation:
Enzymes are biological catalysts that speed up chemical reactions in living organisms. They do this by lowering the activation energy, which is the energy required to start a chemical reaction. Specifically, enzymes achieve this by stabilizing the transition state, the high-energy state that reactants must reach before forming products. By reducing the activation energy for the rate-determining step, enzymes make the reaction occur more rapidly.
Enzymes do not affect the overall equilibrium of a reaction. They speed up both the forward and reverse reactions equally, meaning the position of the equilibrium does not change. The equilibrium constant, which reflects the ratio of the concentration of products to reactants at equilibrium, remains the same in the presence of an enzyme as it would without the enzyme.
The role of enzymes is to accelerate the rate of reaction by providing an alternative pathway with a lower activation energy. They do not change the thermodynamic parameters of the reaction (such as the change in free energy, ΔG). This is why enzymes are not said to shift the equilibrium to favor the product or decrease the equilibrium constant. Their function is purely kinetic, impacting how quickly equilibrium is reached, not its position.
In summary, enzymes work by lowering the energy barrier to the transition state, thereby allowing reactions to proceed at a faster rate without affecting the thermodynamic balance between reactants and products.