Question

Starch and glycogen differ from each other in
(a) Type of glycosidic bonding in straight chains
(b) Type of monomer unit
(c) Type of branching and glycosidic bonding at branches.
(d) Occurrence of coiling in the straight chain and resultant property of interaction with iodine and the components.
(e) Types of cells in which they are present as stored food.

• A. (c) and (d) only
• B. (a) (c) and (d) only.
• C. (a), (c) (d) and (e)
• D. (d) and (e) only.

Answer 1

The correct option is A (c) and (d) only

Starch is the stored form of sugar in plants, a homopolymer of glucose units exist in two forms: amylose which is the helical form of a structure composed of $\alpha$ 1-4 glycosidic linkages, and amylopectin has a structure like glycogen except that $\alpha$ 1- 6 glycosidic linkage present only at branches and amylose in starch is responsible for the formation of deep blue colour in the presence of iodine as it fits into the helix structure whereas

Glycogen is the storage form of sugar in humans and other vertebrates and more highly branched structure than amylopectin but lacks $\alpha$ 1-6 bonding. Glycogen is usually stored in liver and muscle cells whereas starch stored in the amyloplast cells in plants.

So, the correct answer is 'c and d'.