Final answer:
Glycogen is the storage form of glucose in humans and other vertebrates. It is primarily stored in the liver and muscle cells. Glycogen is broken down into glucose when blood glucose levels decrease.
Step-by-step explanation:
Glycogen is the storage form of glucose in humans and other vertebrates. It is made up of monomers of glucose and is primarily stored in the liver and muscle cells. Liver glycogen provides glucose to other cells and helps maintain normal blood glucose levels, while muscle glycogen serves as a readily available source of glucose during exercise and muscle activity.
When blood glucose levels decrease, glycogen is broken down into glucose through a process called glycogenolysis. The presence of glycogen allows ATP to be produced for a longer period of time during exercise, supporting muscle activity.