Final answer:
Glycogen is the storage form of glucose found in liver and muscle cells of animals, acting as an easily mobilized energy reserve for when glucose levels in the blood are low. The correct option is 4.
Step-by-step explanation:
The polysaccharide that serves as a storage form of energy in muscle and liver cells is glycogen. Glycogen is made up of monomers of glucose and is highly branched, allowing for rapid release of glucose when energy is needed.
It is mainly stored in the liver, comprising about 4%-8% by weight of tissue, and in muscle cells, where it's about 0.5%-1.0%. Glycogen functions as an energy reserve that can be quickly mobilized to meet sudden needs for glucose.
When blood glucose levels decrease, glycogenolysis occurs, which is the process of breaking down glycogen into glucose to be used by the body.
This process is crucial for maintaining metabolic balance, especially during fasting or between meals. Since glycogen is more soluble in water due to its structure, compared to cellulose which is not used for energy storage, it can be quickly hydrolyzed into glucose units. Option 4. is the correct one.