Which carbohydrate is known for its energy storage capability in animals?

Glycogen is the primary carbohydrate that functions as an energy storage molecule in animals. It is a polysaccharide composed of glucose units, and it is primarily stored in the liver and muscle tissues. When energy is needed, glycogen can be quickly broken down into glucose, which can then be utilized by cells for energy production.

This efficiency in managing energy storage and release makes glycogen particularly important for maintaining blood glucose levels and providing a rapid source of energy during physical activity. In contrast, other carbohydrates listed have different roles; for instance, cellulose is a structural component found in plant cell walls, starch is the primary energy storage form in plants, and fructose is a simple sugar that serves as an immediate source of energy rather than a storage form.