Which of the following lowers the activation energy $E\_a$ of a biochemical reaction?

• A. Product
• B. Substrate
• C. Enzyme
• D. Inhibitor

Answer: (C)

Verified step by step guidance

1. Understand the concept of activation energy: Activation energy is the minimum energy required for a chemical reaction to occur. It is the energy barrier that must be overcome for reactants to be transformed into products.
2. Identify the role of enzymes: Enzymes are biological catalysts that speed up biochemical reactions by lowering the activation energy. They provide an alternative reaction pathway with a lower energy barrier.
3. Differentiate between the options: A substrate is a reactant in a biochemical reaction, and a product is the result of the reaction. Neither directly affects the activation energy. An inhibitor, on the other hand, typically increases the activation energy or prevents the reaction from occurring by interfering with the enzyme's activity.
4. Focus on the enzyme's mechanism: Enzymes lower activation energy by stabilizing the transition state, reducing the energy required to reach it. They achieve this through various mechanisms, such as providing an active site where substrates can be brought together in an optimal orientation.
5. Conclude with the correct choice: Based on the understanding of enzyme function, it is clear that enzymes are the entities that lower the activation energy of a biochemical reaction, facilitating the conversion of substrates into products more efficiently.