Question

Which of the following statements are/is correct.
I.Amylose doesn’t give a blue colored solution with iodine.
II.Amylopectin gives a blue colored solution with iodine.
III.Amylum is present is rice, maize, wheat, potatoes, barley, sorghum etc.
IV.Amylose is a linear polymer of D-glucose unit.
A) I and II
B) III and IV
C) I and III
D) II and III

Answer 1

Hint: We have to know that amylose is a straight chain of polymer D-glucose unit whereas Amylopectin is a branched chain of polymer D-glucose. Amylose has $20\% $ starch in it whereas amylopectin constitutes 80% of starch. Amylopectin molecules are linked by \[\alpha - 1,4 - \]glycosidic bonds and \[\alpha - 1,6 - \]glycosidic bonds.

Complete answer:
We will look for the correct explanation of the statements given.
This statement is incorrect as Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine.
This statement is incorrect as amylopectin gives reddish brown color in presence with iodine.
This is a correct statement as Amylum is present in rice, maize, wheat, potatoes, barley, sorghum etc.
This statement is correct as Amylose is a non branched linear molecule polymer composed of \[\alpha - 1,4 - d - \]glucose units linked by \[\alpha - d - \left( {1-4} \right)\]linkages.
Option A) this is an incorrect option as statements I and II are not correct.
Option B) this is a correct option as statements III and IV are correct.
Option C) this is an incorrect option as statement I is not correct but statement III is correct. Since one is not correct thus this is an incorrect option.
Option D) this is an incorrect option as statement II is not correct but statement III is correct. Since one is not correct thus this is an incorrect option.

Note:
We must have to know that amylose is a polysaccharide made of several D-glucose units. They are linked by 1,4-glycosidic bonds. Amylose is soluble in water and can be hydrolyzed into glucose units by the enzymes \[\alpha \]- amylase and \[\beta \] -amylase. Amylopectin is a polymer of several D-glucose molecules. 80% of amylopectin is present in starch. Amylopectin molecules are linked by \[\alpha - 1,4 - \]glycosidic bonds and \[\alpha - 1,6 - \]glycosidic bonds.