Question

Consider the following statements: I. Cellulose contains only \(\beta(1\rightarrow4)\) glycosidic linkages. II. Starch contains both \(\alpha(1\rightarrow4)\) and \(\alpha(1\rightarrow6)\) glycosidic linkages.

• A. Both I and II
• B. Neither I nor II
• C. Only II
• D. Only I

Hint:

Cellulose contains only \(\beta(1\rightarrow4)\) linkages, whereas starch contains \(\alpha(1\rightarrow4)\) and \(\alpha(1\rightarrow6)\) linkages due to branching in amylopectin.

Answer 1

The Correct Option is A

Concept: Cellulose and starch are important polysaccharides composed of glucose units but differ in the nature of glycosidic linkages.

Step 1: Examining cellulose. Cellulose consists of long chains of \(\beta\)-D-glucose units connected by \[ \beta(1\rightarrow4) \] glycosidic bonds. No \((1\rightarrow6)\) branching is present. Thus Statement I is correct.

Step 2: Examining starch. Starch consists mainly of two components:
• Amylose
• Amylopectin Amylose contains \[ \alpha(1\rightarrow4) \] linkages. Amylopectin contains \[ \alpha(1\rightarrow4) \] as well as \[ \alpha(1\rightarrow6) \] branching linkages. Therefore starch contains both types. Hence Statement II is correct.

Step 3: Conclusion. Both statements are true. \[ \boxed{(A)} \]