How does an enzyme affect a chemical reaction?

• A. It lowers the activation energy required for the reaction to proceed.
• B. It permanently alters the substrate into a different enzyme.
• C. It raises the activation energy, slowing down the reaction.
• D. It increases the overall free energy change (\( \Delta G \)) of the reaction.

Answer: (A)

Verified step by step guidance

1. Understand the role of enzymes in chemical reactions: Enzymes are biological catalysts that speed up reactions by lowering the activation energy required for the reaction to proceed. They do not alter the overall free energy change ( $∆G$ ) of the reaction.
2. Clarify the concept of activation energy: Activation energy is the minimum energy required for reactants to transform into products. Enzymes lower this energy barrier, making it easier for the reaction to occur.
3. Examine the enzyme-substrate interaction: Enzymes bind to specific substrates at their active site, forming an enzyme-substrate complex. This interaction stabilizes the transition state and reduces the activation energy.
4. Address the incorrect options: Enzymes do not permanently alter themselves or the substrate into a different enzyme. They also do not raise the activation energy or increase the overall free energy change ( $∆G$ ).
5. Conclude with the correct answer: The correct explanation is that enzymes lower the activation energy required for the reaction to proceed, facilitating faster reaction rates without being consumed in the process.