JEE Main · 2022 · Shift-ImediumBIO-025

A polysaccharide 'X' on boiling with dil H2SO4 at 393 K under 2-3 atm pressure yields 'Y'. 'Y' on treatment with…

Biomolecules · Class 12 · JEE Main Previous Year Question

Question

A polysaccharide 'X' on boiling with dil \ceH2SO4\ce{H2SO4} at 393 K393\text{ K} under 23 atm2-3\text{ atm} pressure yields 'Y'. 'Y' on treatment with bromine water gives gluconic acid. 'X' contains β\beta-glycosidic linkages only. Compound 'X' is:

Options
  1. a

    Starch

  2. b

    Cellulose

  3. c

    Amylose

  4. d

    Amylopectin

Correct Answerb

Cellulose

Detailed Solution

Step 1: Polysaccharide Hydrolysis — Boiling polysaccharide 'X' with acid yields 'Y' (glucose), as confirmed by its oxidation to gluconic acid with bromine water.

Step 2: Linkage Specificity — The question states 'X' contains only β\beta-glycosidic linkages. Starch, amylose, and amylopectin all contain α\alpha-glycosidic linkages.

Step 3: Conclusion — Cellulose is a linear polymer of D-glucose\text{D-glucose} units joined exclusively by β-1,4-glycosidic\beta\text{-1,4-glycosidic} linkages, making it the correct compound.

Common Mistake: Confusing the α\alpha-linkages in starch with the β\beta-linkages in cellulose.

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A polysaccharide 'X' on boiling with dil H2SO4 at 393 K under 2-3 atm pressure yields 'Y'. 'Y' on… (JEE Main 2022) | Canvas Classes