Final answer:
The primary function of carbohydrates is energy storage, as they are broken down into glucose to provide energy in the form of ATP for cellular functions and also offer structural support in organisms.
Step-by-step explanation:
The primary function of carbohydrates is energy storage. Carbohydrates, including sugars and starches, are vital for providing energy to cells and come in various forms such as monosaccharides (e.g., glucose), disaccharides, and polysaccharides (e.g., glycogen in animals and starch in plants).
They are broken down into glucose, which through metabolic pathways, is converted into ATP, the primary fuel molecule for cellular functions. Besides energy storage, carbohydrates also offer structural support as seen in substances like cellulose in plant cell walls and chitin in fungi and animals.