C. Enzymes can only be used once in a chemical reaction.
Explanation: Enzymes are biological molecules that act as catalysts in chemical reactions. While enzymes facilitate chemical reactions, they themselves are not consumed or used up in the process. This is a fundamental characteristic of enzymes—they can be used repeatedly in multiple reactions.
Here's how it works:
1. Enzymes bind to specific substrates (the molecules upon which they act) to form enzyme-substrate complexes.
2. Enzymes lower the activation energy required for a chemical reaction to occur, which speeds up the reaction.
3. After the reaction is complete, enzymes release the products of the reaction, and they are free to bind to other substrates and catalyze additional reactions.
This ability of enzymes to be reused makes them highly efficient and essential for many biochemical processes in living organisms. Enzymes can facilitate thousands of reactions per second, maintaining the metabolic processes necessary for life.