Question

On hydrolysis, which of the following carbohydrates gives only $\mathrm{\beta}$-glucose ?

• A. Starch
• B. Sucrose
• C. Maltose
• D. Cellulose

Hint:

Cellulose is a β(1→4) chain of glucose, so it gives only β-glucose.

Answer 1

The Correct Option is D

Step 1: Hydrolysis gives back the building blocks.
Breaking a carbohydrate with water releases whatever sugar units were used to build it. So the question simplifies to, which of these is made purely from $\mathrm{\beta}$-glucose units.

Step 2: Check what each one is built from.
Starch and maltose are constructed from $\mathrm{\alpha}$-glucose, so they release $\mathrm{\alpha}$-glucose on hydrolysis. Sucrose is a mixed sugar that splits into glucose and fructose, so it cannot give pure $\mathrm{\beta}$-glucose either.

Step 3: Focus on cellulose.
Cellulose is a long unbranched chain made entirely of $\mathrm{\beta}$-D-glucose units linked by $\mathrm{\beta}$(1→4) bonds. When those bonds are hydrolysed, the only sugar that comes out is $\mathrm{\beta}$-D-glucose.

Step 4: Conclusion.
\[ \boxed{\text{Option (D): Cellulose}} \]