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Biomolecules

JEE Main 2026 (Online) 23rd January Morning ShiftMCQMedium📈 Topic in 25% papers+4−1
Ques. 1JEE Main 2026, 23 January (Morning Shift)

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

Answer

(4) B and C

Solution

A sugar reduces Tollens' reagent only if its anomeric carbon (the carbon joined to the ring O) carries a free –OH (hemiacetal), because then the ring opens in solution to give the open-chain –CHO form.

A: β-D-glucopyranose; anomeric C has –OH (hemiacetal) reacts

B: methyl glucopyranoside; anomeric C has -OCH3 (acetal, glycoside) ring cannot open, does not react

C: methyl furanoside; anomeric C has -OCH3 (acetal, glycoside) does not react

D: α-D-galactopyranose; anomeric C has –OH (hemiacetal) reacts

B and C do not react with Tollens' reagent.

Answer: (4)

Keep practising — Biomolecules

Ques. 2JEE Main 2026, 23 January (Evening Shift)

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
Ques. 3JEE Main 2026, 22 January (Morning Shift)

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
Ques. 4JEE Main 2026, 22 January (Evening Shift)

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
Ques. 5JEE Main 2026, 21 January (Morning Shift)

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
Ques. 6JEE Main 2026, 21 January (Evening Shift)

The correct statements are : Choose the correct answer from the options given below :

  1. A, B and D Only
  2. A, C and D Only
  3. B and C Only
  4. A and B Only
Ques. 7JEE Main 2025, 8 April (Evening Shift)

[figure] Choose the correct option for structures of A and B, respectively

  1. [figure] and [figure]
  2. [figure] and [figure]
  3. [figure] and [figure]
  4. [figure] and [figure]
Ques. 8JEE Main 2025, 7 April (Morning Shift)

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. Statement I is false but Statement II is true
  3. Both Statement I and Statement II are true
  4. Statement I is true but Statement II is false
Ques. 9JEE Main 2025, 7 April (Evening Shift)

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

  1. Statement I is incorrect but Statement II is correct
  2. Both Statement I and Statement II are incorrect
  3. Both Statement I and Statement II are correct
  4. Statement I is correct but Statement II is incorrect
Ques. 10JEE Main 2025, 4 April (Morning Shift)

Identify the pair of reactants that upon reaction, with elimination of HCl will give rise to the dipeptide Gly-Ala.

  1. NH2-CH2-COOH and NH2- CH3 |CH-COOH
  2. NH2-CH2-COCl and NH3- CH3 |CH-COCl
  3. NH2-CH2-COCl and NH2- CH3 |CH-COOH
  4. NH2-CH2-COOH and NH2- CH3 |CH-COCl
Ques. 11JEE Main 2025, 4 April (Morning Shift)

The total number of hydrogen bonds of a DNA-double Helix strand whose one strand has the following sequence of bases is . 5'-G-G-C-A-A-A-T-C-G-G-C-T-A-3'

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