A polysaccharide $[\mathrm{X}]$ represented as $\left(\mathrm{C}_6 \mathrm{H}_{10} \mathrm{O}_5\right)$ n serves as a reserve carbohydrate in human beings. An enzyme Phosphorylase breaks it down to glucose when required. It is also found in yeast and fungi. What is $[\mathrm{X}]$ ?

The polysaccharide represented by the formula $(\mathrm{C}_6 \mathrm{H}_{10} \mathrm{O}_5)_n$ is a polymer of glucose. Among the given options, glycogen is the primary reserve carbohydrate in humans and animals, stored mainly in the liver and muscles. It is also known as animal starch and is found in yeast and fungi. Glycogen is broken down into glucose-1-phosphate by the enzyme glycogen phosphorylase during glycogenolysis to meet the body's energy requirements. Cellulose is a structural polysaccharide in plants, while starch and amylose are reserve carbohydrates in plants.

Answer: Glycogen