JEE Main 2026 — Biomolecules Question with Solution
JEE Main 2026 (05 April Shift 2)
Question
Given below are two statements :
Statement I: The two cyclic forms of D-(+)-glucose (α and β anomers differing at C1 hydroxyl orientation) are two anomers of D-(+)-glucose.
Statement II: The open chain forms of D-glucose and D-fructose contain three similar chiral carbons at , and .
In the light of the above statements, choose the correct answer from the options given below :
Statement I: The two cyclic forms of D-(+)-glucose (α and β anomers differing at C1 hydroxyl orientation) are two anomers of D-(+)-glucose.
Statement II: The open chain forms of D-glucose and D-fructose contain three similar chiral carbons at , and .
In the light of the above statements, choose the correct answer from the options given below :
Choose an option
Show full solutionCorrect option: A
Correct answer
ABoth Statement I and Statement II are true
Step-by-step explanation
Statement I is true because the and forms of D-(+)-glucose are cyclic hemiacetals that differ only in the configuration of the hydroxyl group at C1, which is the anomeric carbon. Such isomers are called anomers.
Statement II is true because the open chain structures of D-glucose and D-fructose have identical configurations at C3, C4, and C5. D-glucose is an aldohexose with chiral centers at C2, C3, C4, and C5, while D-fructose is a ketohexose with chiral centers at C3, C4, and C5. The stereochemistry at C3 (hydroxyl group on the left), C4 (hydroxyl group on the right), and C5 (hydroxyl group on the right) is exactly the same in both sugars.
Therefore, both Statement I and Statement II are true.
Answer: Both Statement I and Statement II are true
Statement II is true because the open chain structures of D-glucose and D-fructose have identical configurations at C3, C4, and C5. D-glucose is an aldohexose with chiral centers at C2, C3, C4, and C5, while D-fructose is a ketohexose with chiral centers at C3, C4, and C5. The stereochemistry at C3 (hydroxyl group on the left), C4 (hydroxyl group on the right), and C5 (hydroxyl group on the right) is exactly the same in both sugars.
Therefore, both Statement I and Statement II are true.
Answer: Both Statement I and Statement II are true
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This is a previous-year question from JEE Main 2026, covering the Biomolecules chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.