Two types of starch are amylose and amylopectin.

• A. cellulose and glycogen
• B. glucose and fructose
• C. amylose and amylopectin
• D. starch and cellulose

Answer: (C)

Starch consists of two components: amylose and amylopectin. Amylose is a mostly linear polymer of glucose linked by α-1,4 glycosidic bonds, which gives it a helical shape. Amylopectin is a branched polymer with α-1,4 linkages in the chains and α-1,6 branches at intervals, creating a highly branched structure. Together, these two forms make up starch, the storage polysaccharide in plants. The other substances listed aren’t starch, for example cellulose is a β-1,4 linked polymer of glucose forming plant cell walls, glycogen is the animal storage polysaccharide with even more branching, and glucose and fructose are simple sugars. Hence, amylose and amylopectin are the two types that constitute starch.