15. What is the role of enzymes in biological reactions? 11 a. They act as inhibitors. b. They act as catalysts. c. They act as reactants.

**15. What is the role of enzymes in biological reactions?****b. They act as catalysts.****Explanation:** Enzymes are proteins that speed up chemical reactions in the body by lowering the activation energy required for the reaction to proceed. They do this without being consumed in the process, making them highly efficient catalysts.