JEE Main · Chemistry ↓ Falling

Biomolecules appeared 36 times across 3 years — 4.2% of Chemistry. This question is from Nucleic Acids.

Year 2026 2025 2024 Total
Questions 9 19 8 36
Practice all Biomolecules questions → View full JEE Main weightage & trends →

Both human DNA and RNA are chiral molecules. The chirality in DNA and RNA arises due to the presence of

Solution & Explanation

Core Logic

Nucleic acids (DNA and RNA) are composed of three fundamental building blocks: nitrogenous bases, a pentose sugar, and phosphate groups. The nitrogenous bases are planar and generally achiral. The phosphate groups are also achiral. The chirality in both DNA and RNA originates strictly from their pentose sugar components, which have multiple chiral carbon centers.

Step 1: Identifying the specific sugar

DNA contains β-D-2-deoxyribose, and RNA contains β-D-ribose. Both of these are chiral D-sugar components.

Pattern Recognition

Any question asking about the source of chirality in nucleic acid backbones always points to the pentose sugar ring (D-sugar component).

Chapter Mix

Class 12 Chemistry: Biomolecules

Reference Study Guides

Biomolecules

More Biomolecules Previous-Year Questions — Page 8

Q78 jee_main_2024_31_jan_morning Reactions of Glucose
Match List I with List II
LIST-ILIST-II
A. Glucose/NaHCO₃/ΔI. Gluconic acid
B. Glucose/HNO₃II. No reaction
C. Glucose/HI/ΔIII. n-hexane
D. Glucose/Bromine waterIV. Saccharic acid
Choose the correct answer from the options given below:
  • A. A-IV, B-I, C-III, D-II
  • B. A-II, B-IV, C-III, D-I
  • C. A-III, B-II, C-I, D-IV
  • D. A-I, B-IV, C-III, D-II

Solution

Core Logic

Matching the reactions of glucose: (A) Glucose does not react with NaHCO₃, so there is no reaction. (A arrow II) (B) Oxidation of glucose with strong oxidizing agents like HNO₃ yields a dicarboxylic acid called saccharic acid. (B arrow IV) (C) Prolonged heating of glucose with HI forms n-hexane, indicating a straight chain of six carbon atoms. (C arrow III) (D) Oxidation with mild agents like bromine water converts glucose to gluconic acid. (D arrow I)

Chapter Mix

Class 12 Chemistry: Biomolecules

More Biomolecules Questions — jee_main_2026_23_january_evening

Practice all Biomolecules previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)