Atomos Test Generator Free PYQs ExamsMy practice Log in / Sign up free

Biomolecules

JEE Main 2026 (Online) 5th April Evening ShiftMCQEasy📈 Topic in 24% papers+4−1
Ques. 1JEE Main 2026, 5 April (Evening Shift)

Identify the incorrect statement about tertiary structure of proteins.

  1. They can be fibrous or globular in structure.
  2. The main forces that stabilize the structure are hydrogen bonding, disulphide links, van der Waals and electrostatic forces of attraction.
  3. The structure remains intact when exposed to pH changes.
  4. A linear polypeptide chain will convert to a secondary structure and then further folding of the secondary structure will convert to tertiary structure.

Answer

(3) The structure remains intact when exposed to pH changes.

Solution

(A) As per NCERT, the tertiary structure gives rise to two major molecular shapes – fibrous and globular ⇒ correct

(B) The tertiary structure is stabilised by hydrogen bonds, disulphide linkages, van der Waals and electrostatic forces of attraction ⇒ correct

(C) A change in pH disturbs the hydrogen bonds and ionic interactions; the protein uncoils and loses its 2° and 3° structure (denaturation), while the 1° structure stays intact ⇒ incorrect

(D) Polypeptide chain → coiling into secondary structure (α-helix / β-pleated sheet) → further folding into tertiary structure ⇒ correct

∴ The incorrect statement is (C).

Answer: (3)

Keep practising — Biomolecules

Ques. 2JEE Main 2026, 5 April (Evening 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 true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
Ques. 3JEE Main 2026, 4 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 true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
Ques. 4JEE Main 2026, 4 April (Morning Shift)

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

  1. A-II, B-I, C-IV, D-III
  2. A-IV, B-III, C-II, D-I
  3. A-III, B-IV, C-I, D-II
  4. A-II, B-IV, C-I, D-III
Ques. 5JEE Main 2026, 4 April (Evening Shift)

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]
Ques. 6JEE Main 2026, 2 April (Morning Shift)

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
Ques. 7JEE Main 2026, 2 April (Evening Shift)

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
Ques. 8JEE Main 2026, 28 January (Morning Shift)

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
Ques. 9JEE Main 2026, 28 January (Evening Shift)

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10JEE Main 2026, 24 January (Evening Shift)

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
Ques. 11JEE 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

All Biomolecules PYQs →

PDFDownload Biomolecules PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All JEE Main Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolid StateSolutionsElectrochemistryChemical Kinetics
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular Structures-Block Elementsp-Block Elements (Group 13 & 14)Environmental ChemistryGeneral Principles of Isolation of Elementsp-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPrinciples Related to Practical Chemistry