What role do enzymes play in biological reactions?

Enzymes serve a crucial function in biological reactions as biological catalysts. This means that they increase the rate of reactions without being consumed or permanently altered by the reaction process. They achieve this by lowering the activation energy required for the reaction to proceed, allowing substrates to be transformed into products more efficiently.

This catalytic activity enables various biochemical processes, such as metabolism, digestion, and DNA replication, to occur at rates essential for life. Importantly, because enzymes are not changed permanently by the reactions they facilitate, they can continue to function repeatedly, further supporting their role as catalysts in cellular processes.

The other options do not accurately represent the role of enzymes: they do not alter the chemical composition of substrates in a permanent way, nor do they slow down reaction rates. Enzymes also do not undergo permanent changes after catalyzing a reaction; instead, they can be reused and remain available for subsequent reactions.