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Biomolecules

JEE Main 2025 (Online) 4th April Morning ShiftMCQEasy📈 Topic in 24% papers+4−1
Ques. 1JEE 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

Answer

(3) NH2-CH2-COCl and NH2- CH3 |CH-COOH

Solution

In the dipeptide Gly-Ala, the –CO– of glycine is joined to the –NH– of alanine (N-terminal residue written first):

NH2-CH2-CO-NH- CH3 |CH-COOH

To form this amide bond with loss of HCl, glycine must react as its acid chloride and alanine through its free -NH2 group:

NH2-CH2-COCl + NH2- CH3 |CH-COOH

NH2-CH2-CO-NH- CH3 |CH-COOH + HCl

(A) would need loss of water, not HCl. (D) loses HCl but joins the –CO– of alanine to the –NH– of glycine, giving Ala-Gly. In (B) the - NH3 group has no lone pair to attack.

Answer: (3)

Keep practising — Biomolecules

Ques. 2JEE 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'

Ques. 3JEE Main 2025, 4 April (Evening Shift)

A dipeptide, "x" on complete hydrolysis gives "y" and "z". "y" on treatment with aq. HNO2 produces lactic acid. On the other hand "z" on heating gives the following cyclic molecule. [figure] Based on the information given, the dipeptide "x" is :

  1. alanine-alanine
  2. valine-glycine
  3. valine-leucine
  4. alanine-glycine
Ques. 4JEE Main 2025, 3 April (Morning Shift)

Which of the following is the correct structure of L-Fructose?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 5JEE Main 2025, 3 April (Evening Shift)

Fat soluble vitamins are: Choose the correct answer from the options given below:

  1. B & C Only
  2. C & D Only
  3. C & E Only
  4. A & B Only
Ques. 6JEE Main 2025, 2 April (Morning Shift)

Identify the correct statement among the following :

  1. All naturally occurring amino acids except glycine contain one chiral centre.
  2. Amino acid, cysteine can easily undergo dimerisation due to the presence of free SH group.
  3. Glutamic acid is the only amino acid that contains a –COOH group at the side chain.
  4. All naturally occurring amino acids are optically active.
Ques. 7JEE Main 2025, 2 April (Evening Shift)

A tetrapeptide, "x" on complete hydrolysis produced glycine (Gly), alanine (Ala), valine (Val), leucine (Leu) in equimolar proportion each. The number of tetrapeptides (sequences) possible involving each of these amino acids is:

  1. 32
  2. 24
  3. 8
  4. 16
Ques. 8JEE Main 2025, 29 January (Morning Shift)

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

  1. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
  2. (A)-(III), (B)-(III), (C)-(I), (D)-(IV)
  3. (A)-(IV), (B)-(I), (C)-(III), (D)-(II)
  4. (A)-(IV), (B)-(I), (C)-(II), (D)-(III)
Ques. 9JEE Main 2025, 29 January (Evening Shift)

Identify the essential amino acids from below: Choose the correct answer from the options given below:

  1. (A), (C) and (D) only
  2. (C), (D) and (E) only
  3. (A), (C) and (E) only
  4. (B), (C) and (E) only
Ques. 10JEE Main 2025, 28 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. Statement I is true but Statement II is false
  2. Both Statement I and Statement II are true
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are false
Ques. 11JEE Main 2025, 28 January (Evening Shift)

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

  1. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
  2. (A)-(I), (B)-(II), (C)-(III), (D)-(IV)
  3. (A)-(II), (B)-(IV), (C)-(III), (D)-(I)
  4. (A)-(IV), (B)-(II), (C)-(I), (D)-(III)

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