Which polysaccharide is used in energy storage?

Glycogen is the correct answer because it serves as a primary form of energy storage in animals and fungi. It is a branched polysaccharide made up of glucose units, which can be hydrolyzed to release glucose when energy is needed. This is crucial for maintaining blood glucose levels during times of fasting or intense physical activity.

In contrast, cellulose is a structural polysaccharide found in the cell walls of plants and is not utilized for energy storage. Chitin, while a polysaccharide, primarily functions as a structural component in the exoskeletons of arthropods and in fungal cell walls. Carrageenan is a polysaccharide derived from red seaweed and is primarily used as a thickening and stabilizing agent in food products, rather than for energy storage. Thus, glycogen stands out as the polysaccharide specifically designated for energy storage functions in biological systems.