What are glycogen and starch primarily composed of?

Glycogen and starch are primarily composed of branched glucose chains, which is why this response is the correct choice. Both glycogen and starch are polysaccharides that serve as energy storage in living organisms.

Glycogen, found in animals, is highly branched, allowing for rapid mobilization of glucose units when energy is needed quickly. This branching structure enables enzymes to break down glycogen efficiently, making glucose readily available to meet energy demands.

Starch, found in plants, also consists of glucose units but can be made up of both unbranched and branched chains. Its structure allows for a slower release of glucose compared to glycogen, providing a more sustained source of energy.

Overall, the branched structure of glucose chains in both glycogen and starch is critical for their functional roles in energy storage and mobilization in organisms.