Briefly describe the structural differences for each pair listed: A) Glycogen and Cellulose   B) Lactose and Sucrose

Glycogen is the form in which glucose is stored in bacteria, fungi and animals. In humans, glycogen is produced and stored in the liver and muscles. Glycogen stored in muscle cells is broken down into glucose molecules, which provide energy for the muscle. However, when glycogen from the liver is broken down, the glucose which is made available for other tissues of the body. 

Cellulose is a polypeptide which is the main component of the cell wall of a plant cell. Therefore it provides the structural support for the plant cell. Cellulose is also the most abundant organic polymer on earth. While cellulose can be digested by organisms such as termites but it is indigestible by humans.

Lactose is a disaccharide which is abundantly found in milk and milk products such as cheese. It can be digested by the enzyme lactase, however, some humans are lactose intolerant as they lack the ability to digest lactose. 

Sucrose is a disaccharide which is naturally produced in plants. Sucrose is extracted from sugar-cane and used for human consumption as refined sugar. Sucrose undergoes hydrolysis to form glucose and fructose.