Identify the carbohydrate which is not a polysaccharide
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Cane sugar
Carbohydrates are classified by the number of monosaccharide units they give on hydrolysis. A disaccharide gives two units, while a polysaccharide gives a large number of units.
Cane sugar is sucrose, \( \ce{C12H22O11} \), a disaccharide. On hydrolysis it gives one molecule of glucose and one of fructose:
\( \displaystyle \ce{C12H22O11 + H2O} \xrightarrow{\ce{H+}} \ce{C6H12O6\,(glucose) + C6H12O6\,(fructose)} \)
Starch, cellulose and glycogen are all polysaccharides of glucose, so cane sugar is the carbohydrate that is not a polysaccharide.
Option (1) Starch — A polysaccharide. It is the storage polysaccharide of plants, made of amylose and amylopectin, both chains of α-D-glucose.
Option (2) Cellulose — A polysaccharide. It is the structural polysaccharide of plant cell walls, a straight chain of β-D-glucose units.
Option (3) Cane sugar — Not a polysaccharide. It is sucrose, a disaccharide of glucose and fructose.
Option (4) Glycogen — A polysaccharide. It is the storage polysaccharide of animals (“animal starch”), with a highly branched structure like amylopectin.
NCERT (2026-27 edition):
Classification of Carbohydrates – …
