What role do enzymes play in biological reactions?

Enzymes primarily function as catalysts in biological reactions, which means they significantly increase the rate of these reactions without being consumed in the process. By lowering the activation energy required for a reaction to occur, enzymes enable complex biochemical transformations to take place more rapidly and efficiently than they would in the absence of an enzyme.

This catalytic activity is crucial in metabolic pathways, where enzymes facilitate essential life-sustaining processes, such as digestion and energy production. The specificity of enzymes, which often work on specific substrates, is also vital for regulating metabolic pathways and ensuring that the correct biochemical reactions occur at appropriate rates within cells.

The other options do not accurately describe the role of enzymes. While they do not serve as reactants themselves, supply energy, or inhibit all reactions, they maintain integral roles in facilitating and regulating reactions critical for life. Thus, recognizing enzymes as catalysts emphasizes their importance in biological systems.