Final answer:
Monosaccharides are the building blocks of carbohydrates providing energy for cells, while disaccharides provide a source of energy. Polysaccharides serve as energy storage molecules or structural components in organisms.
Step-by-step explanation:
Carbohydrates play important roles in living organisms. Monosaccharides are the basic building blocks of carbohydrates and provide energy for cells. Examples of monosaccharides include glucose, fructose, and galactose. Disaccharides are formed by the bonding of two monosaccharides and serve as a source of energy, such as sucrose and lactose. Polysaccharides are complex carbohydrates made up of many monosaccharide units and serve as energy storage molecules or structural components in organisms. Examples include starch, glycogen, cellulose, and chitin.