Cellulose is a _____ polymer composed of _____.

The correct answer is Option (3) → Linear, $β$-D-glucose

Core Concept:

Cellulose is formed by β-1,4 glycosidic linkage of glucose units.

Explanation:

Cellulose is a polysaccharide made up of β-D-glucose units linked together through β-1,4-glycosidic bonds. These linkages produce a straight chain structure, making cellulose a linear polymer. Unlike starch, which contains α-linkages and branching, cellulose remains unbranched due to its bonding pattern.

Option 1: Linear, α-D-glucose

Incorrect because cellulose contains β-D-glucose, not α.

Option 2: Branched, β-D-glucose

Incorrect because cellulose is not branched.

Option 3: Linear, β-D-glucose

Correct because cellulose is a linear polymer of β-D-glucose.

Option 4: Branched, α-D-glucose

Incorrect because both structure and glucose type are wrong.