Cellulose does not form blue colour with Iodine because

Cellulose does not form blue colour with Iodine because
  1. It breaks down when iodine reacts with it.
  2. It is a disaccharide.
  3. It is a helical molecule.
  4. It does not contain complex helices and hence cannot hold iodine molecules.

Solution

Cellulose is a polymeric polysaccharide consisting of only one type of monosaccharide, i.e., glucose. Cellulose is a homopolymer. Starch is a variant of this but is present as a storehouse of energy in plant tissues. Starch forms helical secondary structures, and it can hold iodine molecules in the helical portion. The starch-iodine is blue. Cellulose does not contain complex helices and hence cannot hold iodine.

Asked in: NEET 2023 (All India)

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