Which carbohydrate functions as the main energy storage carbohydrate in animals?

• A. Starch is the main energy storage carbohydrate in animals.
• B. Glycogen is the main energy storage carbohydrate in animals.
• C. Cellulose is the main energy storage carbohydrate in animals.
• D. Chitin is the main energy storage carbohydrate in animals.

Answer: (B)

Energy storage in animals is carried by glycogen, a highly branched polymer of glucose. This branching makes it possible to release many glucose units quickly when energy is needed, which is ideal for rapid activity. Glycogen is stored mainly in the liver—to help maintain blood glucose between meals—and in skeletal muscle—to supply energy during muscle contraction. In contrast, starch stores energy in plants, while cellulose and chitin serve structural roles (cell walls and exoskeletons, respectively), not energy storage. So glycogen is the main energy storage carbohydrate in animals.