Which of the following statements about enzymes is true?

Enzymes are biological catalysts that play a crucial role in speeding up chemical reactions within living organisms. The statement that they lower the activation energy of reactions is true because enzymes provide an alternative reaction pathway with a lower activation energy compared to the uncatalyzed reaction. This means that more molecules have sufficient energy to undergo the reaction at a given temperature, ultimately increasing the reaction rate.

Lowering the activation energy allows reactions to occur more quickly and efficiently without the enzyme becoming consumed in the process; instead, the enzyme can be reused for multiple reactions. This characteristic makes enzymes essential for facilitating biological processes.

While enzymes do have specific optimal conditions, including temperature and pH, stating that they work optimally at all temperatures is inaccurate since high temperatures can denature enzymes, rendering them ineffective. Additionally, most enzymes are specific to particular substrates rather than being limited to one specific reaction, though they do often catalyze a range of closely related reactions.