Which is an example of a biological catalyst?

• A. Lipids
• B. Enzymes
• C. Nucleic acids
• D. Carbohydrates

Answer: (B)

Biological catalysts are molecules that speed up chemical reactions in living organisms without being consumed. The best example is enzymes, which are typically proteins with a specific shape that forms an active site where substrates bind. When the substrate fits, it creates an enzyme–substrate complex that lowers the activation energy required for the reaction, allowing it to proceed much faster than it would on its own. After the reaction happens, the products are released and the enzyme can catalyze more reactions. Enzymes are highly specific for their substrates and reactions, and their activity can be influenced by factors like temperature, pH, and inhibitors. While RNA can also act as a catalyst in some cases (ribozymes), the common, most familiar biological catalysts are enzymes.

Lipids, nucleic acids, and carbohydrates perform other essential roles—lipids form membranes and store energy, nucleic acids store and transmit genetic information, and carbohydrates provide energy and structural support. They are not used as catalysts in the same way enzymes are.