What is the primary role of carbohydrates in living organisms?

Carbohydrates are essential biomolecules that primarily serve as a key source of energy for living organisms. They are composed of carbon, hydrogen, and oxygen, and their structure allows for the efficient storage and release of energy. During metabolic processes, carbohydrates can be broken down into simpler sugars, such as glucose, which are then used in cellular respiration to produce ATP (adenosine triphosphate), the energy currency of the cell.

In addition to energy provision, carbohydrates also play roles in structural components of cells, such as in cellulose in plants and chitin in fungi. However, their primary and most immediate function is to supply energy for cellular activities, making them a fundamental part of diets across many life forms.

Other options describe functions of different macromolecules: building cell membranes is largely the function of lipids, storing genetic information pertains to nucleic acids, and acting as enzymes describes the role of proteins. Thus, while these other molecules play vital roles in biological systems, carbohydrates are distinctly recognized for their energy-providing capacity.