question_answer

Directions : (11 - 15)

Case III : Read the passage given below an answer the following questions from 11 to 15.

Pentose and hexose undergo intramolecular hemiacetal or hemiketal formation due to combination of the \[-OH\] group with the carbonyl group. The actual structure is either of five or six membered ring containing an oxygen atom.

In the free state all pentoses and hexoses exist in pyranose form (resembling pyran). However, in the combined state some of them exist as five membered cyclic structures, called furanose (resembling furan).

The cyclic structure of glucose is represented by Haworth structure :

\[\alpha \] and \[\beta \]-D-glucose have different configuration at anomeric (C-1) carbon atom, hence are called anomers and the C-1 carbon atom is called anomeric carbon (glycosidic carbon).

The six membered cyclic structure of glucose is called pyranose structure.

\[\alpha \]-D-(+)-glucose and \[\beta \]-D-(+)-glucose are

A) enantiomers

B) conformers

C) epimers

D) anomers.

Correct Answer: D

Solution :

\[\alpha \]-D-(+)-glucose and \[\beta \]-D-(+)-glucose  differ in configuration at \[{{C}_{1}}\] (i.e., anomeric or glycosidic carbon) and hence are called anomers.