What type of molecule speeds up chemical reactions in biological processes?

The correct answer is enzyme, as these molecules are biological catalysts that significantly increase the rate of chemical reactions within cells. Enzymes function by lowering the activation energy required for a reaction to occur, which allows reactions to proceed much more swiftly than they would on their own. This is crucial for various biological processes, including metabolism, DNA replication, and energy production, since many of these reactions would occur too slowly to sustain life without the presence of enzymes.

In contrast, hormones are signaling molecules that regulate physiological processes but do not directly catalyze reactions. Vitamins are organic compounds that often act as coenzymes or cofactors for enzymes, supporting their activity, but are not catalysts themselves. Carbohydrates primarily serve as energy sources and structural components, rather than as accelerators of chemical reactions. Thus, enzymes are uniquely suited to the role of accelerating biochemical reactions, making them essential for life and biological function.