Which of the following is incorrect statement with respect to carbohydrates?

1. Mannose and galactose are polymers of glucose 

2. Cellulose acetate is used in fabrics, cellulosic plastics and shatter proof glasses

3. Most of sugars show Benedict's test but not sucrose

4. Sucrose is composed of glucose and fructose and is a non-reducing sugar

Compounds which consists of only one type of monosaccharide monomer are called homopolysaccharides. Which one of the following does not belong this category?

1. Starch 

2. Pectin

3. Cellulose

4. Glycogen