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Biomolecules · Question 11

JEE Main 2026 (Online) 4th April Evening ShiftMCQHard📈 Topic in 26% papers+4−1
1

A D-aldotetrose on oxidation with concentrated HNO3 resulted in optically inactive dicarboxylic acid. The structure of the D-aldotetrose is:

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(3) [figure]

Solution

An aldotetrose has two chiral carbons (C-2 and C-3). Conc. HNO3 oxidises both –CHO and –CH2OH to –COOH ⇒ 2,3-dihydroxybutanedioic acid (tartaric acid).

It is optically inactive only in the meso form, which has a plane of symmetry ⇒ both –OH on the same side of the Fischer projection.

D-sugar ⇒ –OH on C-3 (the carbon next to –CH2OH) on the right ⇒ –OH on C-2 also on the right ⇒ D-erythrose.

[figure]

∴ Option (3). (Option (4) is D-threose, which gives optically active tartaric acid; (1) and (2) are L-sugars.)

Answer: (3)

JEE Main 2026 (Online) 4th April Evening Shift

Keep practising — Biomolecules

2

Match List - I with List - II.

  1. A-II, B-I, C-III, D-IV
  2. A-IV, B-III, C-II, D-I
  3. A-III, B-IV, C-I, D-II
  4. A-I, B-III, C-II, D-IV
JEE Main 2026 (Online) 2nd April Morning Shift
3

Identify the correct pair having amino acid (A) and the hormone (B) that is iodinated derivative of the amino acid (A). (T and Y represent one letter code for amino acids)

  1. Amino acid (A) - T Hormone (B) - Insulin
  2. Amino acid (A) - T Hormone (B) - Thyroxine
  3. Amino acid (A) - Y Hormone (B) - Thyroxine
  4. Amino acid (A) - Y Hormone (B) - Insulin
JEE Main 2026 (Online) 2nd April Evening Shift
4

In the given pentapeptide, find out an essential amino acid (Y) and the sequence present in the pentapeptide : [figure] Choose the correct answer from the options given below :

  1. arrayll(Y) & (Sequence) \ Serine & Thr-Ser-Asp-Ala-Gly array
  2. arrayll(Y) & (Sequence) \ Serine & Ser-Asp-Thr-Ala-Gly array
  3. arrayll(Y) & (Sequence) \ Threonine & Ser-Thr-Asp-Gly-Ala array
  4. arrayll(Y) & (Sequence) \ Threonine & Thr-Ser-Asp-Gly-Ala array
JEE Main 2026 (Online) 28th January Morning Shift
5

Structures of four disaccharides are given below. Among the given disaccharides, the non-reducing sugar is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 28th January Evening Shift
6

The number of possible tripeptides formed involving alanine (ala), glycine (gly) and valine (val), where no amino acid has been used more than once is:

  1. 8
  2. 3
  3. 4
  4. 6
JEE Main 2026 (Online) 24th January Evening Shift
7

From the given following (A to D) cyclic structures, those which will not react with Tollens' reagent are: [figure]

  1. A and D
  2. A and B
  3. B and D
  4. B and C
JEE Main 2026 (Online) 23rd January Morning Shift
8

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

  1. L-sugar component
  2. D-sugar component
  3. Chiral phosphate unit
  4. Base unit
JEE Main 2026 (Online) 23rd January Evening Shift
9

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are false
  2. Both Statement I and Statement II are true
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 22nd January Morning Shift
10

Match List-I with List-II. Choose the correct answer from the options given below :

  1. A-IV, B-III, C-II, D-I
  2. A-I, B-III, C-IV, D-II
  3. A-III, B-I, C-IV, D-II
  4. A-IV, B-I, C-II, D-III
JEE Main 2026 (Online) 22nd January Evening Shift
11

Identify the correct statements. Choose the correct answer from the options given below :

  1. C and D Only
  2. A and D Only
  3. C and E Only
  4. B and E Only
JEE Main 2026 (Online) 21st January Morning Shift

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