Which of the following describes the function of enzymes?

Enzymes are biological catalysts that play a crucial role in facilitating chemical reactions within living organisms. The primary function of enzymes is to speed up these reactions by lowering the activation energy required for the reaction to occur. By doing so, enzymes increase the rate at which reactions take place, allowing essential biochemical processes to occur more efficiently and under physiological conditions.

Enzymes achieve this catalytic effect without being consumed in the reaction. This means that after an enzyme has facilitated a reaction, it can be reused multiple times to catalyze additional substrate molecules. This characteristic is vital, as it allows for efficient use of enzymes within cells, making them indispensable for numerous metabolic pathways.

Overall, the correct answer reflects the fundamental role of enzymes in biology, highlighting their ability to enhance reaction rates and their reusable nature.