Question

Pick out the incorrect statement(s) from the following
1. Glucose exists in two different crystalline forms, $\alpha$-D-glucose and $\beta$-D-glucose
2. $\alpha$-D-glucose and $\beta$-D-glucose are anomers
3. $\alpha$-D-glucose and $\beta$-D-glucose are enantiomers
4. Cellulose is a straight chain polysaccharide made of only $\beta$-D-glucose units
5. Starch is a mixture of amylose and amylopectin, both contain unbranched chain of $\alpha$-D-glucose units

• A. 1 and 2 only
• B. 2 and 3 only
• C. 3 and 4 only
• D. 3 and 5 only
• E. 4 and 5 only

Answer 1

Answer: (D)

$\alpha$-D-glucose and $\beta$-D-glucose differ in the orientation of .Hand OH-groups around first carbon atom. Such isomers are called anomers not enantiomers. Starch is a mixture of amylose and amylopectin but amylose is a straight chain polymer of $\alpha$-D-glucose while amylopectin is a branched chain polymer of $\alpha$-D-glucose.