Glycogen is primarily an energy source in which organisms?

• A. plants
• B. animals
• C. fungi
• D. bacteria

Answer: (B)

Glycogen serves as the quick-access glucose storage form in animals. Its highly branched structure allows enzymes to rapidly add or remove glucose units, providing fast energy during activity and helping to maintain blood glucose levels via the liver. Plants store glucose as starch, which is suited for long-term energy storage in seeds and chloroplasts rather than rapid use. While fungi and some bacteria also synthesize glycogen, the primary, readily mobilized energy reserve characterizing whole-animal metabolism is glycogen in animals.