Cellulose is a _____ polymer composed of _____.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Linear, \(β\)-D-glucose
Cellulose, the main constituent of plant cell walls, is a straight chain (linear) polysaccharide made only of β-D-glucose units. They are joined by β-glycosidic links between C1 of one glucose unit and C4 of the next. The β-links let the chains lie straight and pack side by side with many hydrogen bonds, which gives cellulose its strength and makes it insoluble in water. Humans lack the enzyme that breaks β-links, so cellulose is not digested by us.
So cellulose is a linear polymer of β-D-glucose.
Why the other options are incorrect
Option (1) Linear, \(α\)-D-glucose — Incorrect. This describes amylose, the unbranched component of starch, with C1–C4 α-glycosidic links.
Option (2) Branched, \(β\)-D-glucose — Incorrect. Cellulose has no branches; its chains are straight.
Option (4) Branched, \(α\)-D-glucose — Incorrect. This describes amylopectin and glycogen, which have C1–C4 links in the chain and C1–C6 links at the branches.
NCERT (2026-27 edition):
Cellulose
