Most cellular activities are primarily regulated by which type of biological molecules?

The correct choice highlights enzymes as the key regulators of most cellular activities. Enzymes are specialized proteins that act as catalysts, accelerating chemical reactions within cells. They lower the activation energy needed for reactions, which means that metabolic processes can occur more efficiently and at a faster rate. Because enzymes are highly specific, they ensure that the correct biochemical pathways are followed and that the cellular environment is maintained optimally for life processes.

While proteins play various roles in the cell, not all proteins function as enzymes; therefore, they encompass a broader category that includes structural and signaling functions. Nucleic acids, such as DNA and RNA, are primarily involved in the storage and transmission of genetic information rather than directly regulating enzymatic activity. Carbohydrates serve mainly as energy sources and structural components, but they are not key regulators of cellular functions. Hence, focusing on enzymes provides an understanding of how biological processes are executed and controlled within the cell, underscoring their critical importance in cellular regulation.