Enlist the natural sources, structural units and functions of the following polysaccharides. 

a. Starch: 

1. Natural Sources: Cereals (wheat, maize, rice), root vegetables (potato, cassava etc.) 

2. Structural units: Starch consist of two types of molecules – Amylose and amylopectin. 

3. Functions: It acts as a reserve food and supply energy.

b. Cellulose: 

1. Natural sources: Plant fibers (cotton, flax, hemp, jute, etc.), wood. 

2. Structural units: It is made from p glucose molecules. 

3. Functions: It in a major component of cell wall. It provides structural support. 

c. Glycogen: 

1. Natural sources:

Fruits, starchy vegetables, whole grain foods. 

2. Structural units: 

It consists of linear chains of glucose residues. The glucose is linked linearly by a (1 → 4) glycosidic bonds and branches are linked to the linear chain by a (1 → 6) glycosidic bonds. 

3. Functions: 

It is stored in liver and muscles and it readily provides energy when the blood glucose level decreases.