What is the primary function of carbohydrates in biological systems?

The primary function of carbohydrates in biological systems is energy storage. Carbohydrates are a major source of energy for living organisms. They can be quickly broken down into glucose, which is utilized by cells to produce ATP (adenosine triphosphate), the energy currency of the cell. Simple carbohydrates, like sugars, provide immediate energy, while complex carbohydrates, such as starch and glycogen, serve as stored energy reserves that can be mobilized when needed.

While carbohydrates can play roles in other areas like structural support in cell walls of plants (as seen in cellulose), their most significant and fundamental role revolves around energy. Signaling molecules and insulation are functions more commonly associated with proteins and lipids, respectively, rather than carbohydrates. This distinction underlines the importance of carbohydrates as energy sources in biological processes.