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Biomolecules · Question 1

JEE Advanced 2026 Paper 2Multiple CorrectMedium📈 Topic in 17% papers+4−1
1

The correct statement(s) regarding sugars is(are) Given: Specific rotations of L-(−)-glucose and L-(+)-fructose are -52.5 and +92.5 , respectively.

  1. On treatment with HNO3, gluconic acid is oxidized to saccharic acid, whereas glucose is not oxidized to saccharic acid.
  2. Fructose gives a positive Fehling's test because it isomerises to glucose and another aldohexose in the presence of Fehling's reagent.
  3. Invert sugar is an equimolar mixture of D-glucose and D-fructose formed after hydrolysis of the corresponding disaccharide.
  4. Specific rotation of invert sugar is -40 .

Answer

(2) Fructose gives a positive Fehling's test because it isomerises to glucose and another aldohexose in the presence of Fehling's reagent., (3) Invert sugar is an equimolar mixture of D-glucose and D-fructose formed after hydrolysis of the corresponding disaccharide.

Solution

(A) HNO3 oxidises both the CHO and the terminal CH2OH of glucose, so glucose itself gives saccharic acid: wrong.

(B) In alkaline Fehling's solution fructose undergoes enolisation (Lobry de Bruyn–van Ekenstein rearrangement) to glucose and mannose, which reduce Cu2+: correct.

(C) Hydrolysis of sucrose gives equal moles of D-glucose and D-fructose (invert sugar): correct.

(D) D-isomers have the opposite signs: D-glucose +52.5 , D-fructose -92.5 . For the equimolar mixture [ ]= 52.5-92.52=-20 : wrong.

Answer: (B), (C)

JEE Advanced 2026 Paper 2

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2

A known artificial sweetener X is composed of 4-chloro-4-deoxy-α-D-galactose and 1,6-dichloro-1,6-dideoxy-β-D-fructose joined by a glycosidic linkage. Structure of D-galactose is given below: [figure] The correct structure of X is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Advanced 2026 Paper 2
3

A linear octasaccharide (molar mass = 1024 g mol-1) on complete hydrolysis produces three monosaccharides: ribose, 2-deoxyribose and glucose. The amount of 2-deoxyribose formed is 58.26 % (w/w) of the total amount of the monosaccharides produced in the hydrolyzed products. The number of ribose unit(s) present in one molecule of octasaccharide is . Use: Molar mass (in g mol-1): ribose = 150, 2-deoxyribose = 134, glucose = 180; Atomic mass (in amu): H = 1, O = 16

JEE Advanced 2025 Paper 2
4

Aspartame, an artificial sweetener, is a dipeptide aspartyl phenylalanine methyl ester. The structure of aspartame is [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Advanced 2024 Paper 1
5

For a double strand DNA, one strand is given below: [figure] The amount of energy required to split the double strand DNA into two single strands is kcal mol-1. [Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol-1, G-C base pair = 1.5 kcal mol-1, and A-U base pair = 1.25 kcal mol-1. Ignore electrostatic repulsion between the phosphate groups.]

JEE Advanced 2024 Paper 2

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