Question

Starch is composed of amylose and ___________.
A. Amylopectin
B. Maltose
C. Glycogen
D. None of the above

Answer 1

Hint: Starch is polysaccharide containing a large number of monosaccharide units joined together by glycosidic linkages. It is the main storage polysaccharide of plants. Starch is a polymer of $\alpha$-glucose.

Complete step by step solution:
Starch is polysaccharide consisting of two components Amylose and Amylopectin. Amylose is water soluble which constitutes about $15-20\mathrm{\%}$ of starch. Chemically amylose is a long unbranched chain with $$200-1000$$ $\alpha$-D-(+)-glucose units held by C1-C4 glycosidic linkage. Amylose leaves blue stains with iodine. It does not form gel when hot water is added to it.
Amylopectin is insoluble in water. It constitutes about $$80-85\mathrm{\%}$$ of starch. It is a branched chain polymer of $\alpha$-D-glucose units in which chain is formed by C1-C4 glycosidic linkage whereas branching occurs by C1-C6 glycosidic linkage.Amylopectin leaves reddish brown stains with iodine. It forms gel when hot water is added to it.

Hence Correct option is A.

Additional Information:

Glycogen stores carbohydrates in the animal body and its structure is similar to amylopectin. It is more complex in branching.
Maltose is a disaccharide composed of two $\alpha$-D-glucose units in which C1 of one glucose is linked to C4 of another glucose.

Note:
Remember starch is polysaccharide and it consists of only two components amylose and amylopectin. Amylose is more water soluble than amylopectin.