Biomolecules

21 JEE Main questions · Chemistry

ChemistryJEE Main 21 Jan 2026, Shift 1·Q17·MCQ·Easy–moderate
Open
Amino acid structure
Identify the correct statements.
- (A)Arginine and Tryptophan are essential amino acids.
- (B)Histidine does not contain heterocyclic ring in its structure.
- (C)Proline is a six membered cyclic ring amino acid.
- (D)Glycine does not have chiral centre.
- (E)Cysteine has characteristic feature of side chain as $\ce{MeS-CH2-CH2-}$ .
Choose the correct answer from the options given below:
Option
1. (1)C and E Only
2. (2)B and E Only
3. (3)C and D Only
4. (4)A and D Only
ChemistryJEE Main 21 Jan 2026, Shift 2·Q11·MCQ·Easy–moderate
Open
Proteins enzymes and nucleic acids
The correct statements are:
- (A)Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.
- (B)During denaturation, secondary and tertiary structures of a protein are destroyed but primary structure remains intact.
- (C)Nucleotides are joined together by glycosidic linkage between C $_1$ and C $_4$ carbons of the pentose sugar
- (D)Quaternary structure of proteins represents overall folding of the polypeptide chain.
Choose the correct answer from the options given below:
1. (1)A, C and D Only
2. (2)A, B and D Only
3. (3)A and B Only
4. (4)B and C Only
ChemistryJEE Main 22 Jan 2026, Shift 1·Q15·MCQ·Easy–moderate
Open
Inversion of sucrose
Given below are two statements:
Statement I : Sucrose is dextrorotatory. However sucrose upon hydrolysis gives a solution having mixture of products. This solution shows laevorotation.
Statement II : Hydrolysis of sucrose gives glucose and fructose. Since the laevorotation of glucose is more than the dextrorotation of fructose the resulting solution becomes laevorotatory.
In the light of the above statements, choose the correct answer from the options given below.
1. (1)Statement I is false but Statement II is true.
2. (2)Both Statement I and Statement II are false.
3. (3)Both Statement I and Statement II are true.
4. (4)Statement I is true but Statement II is false.

ChemistryJEE Main 22 Jan 2026, Shift 2·Q10·MCQ·Easy

Reactions of glucose

Match List-I with List-II.

List-I	List-II
Reaction of glucose with	Product formed
A. Hydroxylamine	I. Gluconic acid
B. $\ce{Br2}$ water	II. Glucose pentaacetate
C. Excess acetic anhydride	III. Saccharic acid
D. Concentrated $\ce{HNO3}$	IV. Glucoxime

Choose the correct answer from the options given below :

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

We corrected a printing error in the original paper

Source printed “Glouconic acid” and “Glucose pentacetate”.

ChemistryJEE Main 23 Jan 2026, Shift 1·Q14·MCQ·Easy–moderate
Open
Glycosides and reducing sugars
From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :
1. (1)B and D
2. (2)A and D
3. (3)A and B
4. (4)B and C
ChemistryJEE Main 23 Jan 2026, Shift 2·Q4·MCQ·Easy
Open
Nucleic acid sugar chirality
Both human DNA and RNA are chiral molecules. The chirality in DNA and RNA arises due to the presence of
1. (1)Base unit
2. (2)Chiral phosphate unit
3. (3)D-sugar component
4. (4)L-sugar component
ChemistryJEE Main 24 Jan 2026, Shift 2·Q3·MCQ·Easy
Open
Peptide sequences of amino acids
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. (1)6
2. (2)3
3. (3)4
4. (4)8
ChemistryJEE Main 28 Jan 2026, Shift 1·Q14·MCQ·Easy–moderate
Open
Peptide sequence and essential amino acids
In the given pentapeptide, find out an essential amino acid (Y) and the sequence present in the pentapeptide:
Choose the correct answer from the options given below:
1. (1)
  (Y) (Sequence)
  Threonine Ser – Thr – Asp – Gly – Ala
2. (2)
  (Y) (Sequence)
  Serine Thr – Ser – Asp – Ala – Gly
3. (3)
  (Y) (Sequence)
  Threonine Thr – Ser – Asp – Gly – Ala
4. (4)
  (Y) (Sequence)
  Serine Ser – Asp – Thr – Ala – Gly
ChemistryJEE Main 28 Jan 2026, Shift 2·Q11·MCQ·Easy–moderate
Open
Reducing and non-reducing disaccharides
Structures of four disaccharides are given below. Among the given disaccharides, the non-reducing sugar is :
1. (1)
2. (2)
3. (3)
4. (4)
We corrected a printing error in the original paper
Option (1): source printed “OH” on the fructose ring carbon next to the ring oxygen (C-5), which makes that carbon a hemiacetal and leaves no non-reducing option; corrected in the figure to the intended “CH $_2$ OH” (sucrose, source key (1)); glyphs copied from the same drawing.
ChemistryJEE Main 2 Apr 2026, Shift 1·Q19·MCQ·Easy
Open
Vitamins and their names
Match List-I with List-II.
List-I List-II
Vitamin Name
A. Vitamin B $_1$ I. Pyridoxine
B. Vitamin B $_2$ II. Ascorbic acid
C. Vitamin B $_6$ III. Thiamine
D. Vitamin C IV. Riboflavin
Choose the correct answer from the options given below :
1. (1)A-II, B-I, C-III, D-IV
2. (2)A-IV, B-III, C-II, D-I
3. (3)A-III, B-IV, C-I, D-II
4. (4)A-I, B-III, C-II, D-IV
ChemistryJEE Main 2 Apr 2026, Shift 2·Q19·MCQ·Easy
Open
Amino acids and iodinated hormones
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)
Amino acid (A) – Hormone (B)
1. (1)T – Insulin
2. (2)T – Thyroxine
3. (3)Y – Thyroxine
4. (4)Y – Insulin
We corrected a printing error in the original paper
Source printed “Insuline” in options (1) and (4).
ChemistryJEE Main 4 Apr 2026, Shift 1·Q18·MCQ·Easy–moderate
Open
Reducing and non-reducing sugars
Statement-I : The structure of Maltose is given below :
Maltose is a non reducing sugar
Statement-II : The structure of Lactose is given below
Lactose is a reducing sugar
In the light of the above statements, choose the correct answer from the options given below
1. (1)Both Statement I and Statement II are true
2. (2)Both Statement I and Statement II are false
3. (3)Statement I is true but Statement II is false
4. (4)Statement I is false but Statement II is true
ChemistryJEE Main 4 Apr 2026, Shift 1·Q19·MCQ·Easy
Open
Essential amino acids
Match the LIST-I with LIST-II :
List-I List-II
Name of One letter
amino acid symbol/type)
A Arginine I. D / Non-essential
B Aspartic acid II. R / Essential
C Lysine III. E / Non-essential
D Glutamic acid IV. K/Essential
Choose the correct answer from the options given below :
1. (1)A-II, B-I, C-IV, D-III
2. (2)A-IV, B-III, C-II, D-I
3. (3)A-III, B-IV, C-I, D-II
4. (4)A-II, B-IV, C-I, D-III
ChemistryJEE Main 4 Apr 2026, Shift 2·Q18·MCQ·Moderate
Open
Carbohydrate fischer projection
A D-aldotetrose on oxidation with concentrated $\ce{HNO3}$ resulted in optically inactive dicarboxylic acid. The structure of the D-aldotetrose is :
1. (1)
2. (2)
3. (3)
4. (4)
ChemistryJEE Main 5 Apr 2026, Shift 1·Q19·MCQ·Easy–moderate
Open
Anomers of glucose
Identify the correct statements
- (A)Glucose exists in two anomeric forms.
- (B)Anomers of glucose differ in configuration at C-1 in cyclic hemiacetal structure.
- (C)Melting point of $\alpha$ -anomer of glucose is greater than $\beta$ -anomer.
- (D)Specific rotation of $\alpha$ -anomer is $+19^\circ$ while for $\beta$ -anomer is $+112^\circ$
- (E) $\alpha$ and $\beta$ -anomers of glucose are prepared by crystallization of saturated glucose solution at 303 K and 371 K respectively.
Choose the correct answer from the options given below :
1. (1)A and B only
2. (2)B and C only
3. (3)A, B and D only
4. (4)A, B and E only
We corrected a printing error in the original paper
Source printed “Glucose exist in two anomeric forms”.
ChemistryJEE Main 5 Apr 2026, Shift 2·Q18·MCQ·Easy
Open
Protein tertiary structure
Identify the incorrect statement about tertiary structure of proteins.
1. (1)They can be fibrous or globular in structure.
2. (2)The main forces that stabilize the structure are hydrogen bonding, disulphide links, van der Waals and electrostatic forces of attraction.
3. (3)The structure remains intact when exposed to pH changes.
4. (4)A linear polypeptide chain will convert to a secondary structure and then further folding of the secondary structure will convert to tertiary structure.
ChemistryJEE Main 5 Apr 2026, Shift 2·Q19·MCQ·Easy–moderate
Open
Glucose anomers and fructose configuration
Given below are two statements :
Statement-I : and are two anomers of D-(+)-glucose.
Statement-II : The open chain forms of D-glucose and D-fructose contain three similar chiral carbons at C $_3$ , C $_4$ and C $_5$ .
In the light of the above statements, choose the correct answer from the options given below :
1. (1)Both Statement-I and Statement-II are true.
2. (2)Both Statement-I and Statement-II are false.
3. (3)Statement-I is true but Statement-II is false.
4. (4)Statement-I is false but Statement-II is true.
ChemistryJEE Main 6 Apr 2026, Shift 1·Q19·MCQ·Easy
Open
Vitamins and deficiency diseases
Match the List-I with List-II :
List-I List-II
Deficiency Disease Vitamin
A. Scurvy I. Pyridoxine
B. Convulsions II. Vitamin A
C. Cheilosis III. Ascorbic Acid
D. Xerophthalmia IV. Riboflavin
Choose the correct answer from the options given below :
1. (1)A-I, B-III, C-II, D-IV
2. (2)A-I, B-III, C-IV, D-II
3. (3)A-III, B-I, C-IV, D-II
4. (4)A-III, B-I, C-II, D-IV

ChemistryJEE Main 6 Apr 2026, Shift 1·Q20·MCQ·Moderate

Open

Amino acid side chain tests

Match the List-I with List-II

List-I		List-II
Amino acid		Positive reaction/Test for
		functional group present in
		side chain of amino acid
A.	Glutamine	I.	Hinsberg's test
B.	Lysine	II.	Neutral $\ce{FeCl3}$ test
C.	Tyrosine	III.	Ceric ammonium nitrate test
D.	Serine	IV.	Hoffman bromamide degradation

Choose the correct answer from the options given below :

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

ChemistryJEE Main 8 Apr 2026, Shift 2·Q19·MCQ·Easy
Open
Carbohydrate classification and properties
The incorrect statement from the following with respect to carbohydrates is :
1. (1)All monosaccharides are reducing sugars.
2. (2)The monosaccharide units obtained from hydrolysis of oligosaccharides are always the same.
3. (3)Starch and cellulose are typical examples of polysaccharides, which are very high molecular weight compounds of more than ten monosaccharide units.
4. (4)Open chain and cyclic structures co-exist at equilibrium that are responsible for certain properties as in the case of D-(+)-glucose.
ChemistryJEE Main 8 Apr 2026, Shift 2·Q20·MCQ·Easy
Open
Amino acid tests
Which of the following amino acid will give violet coloured complex with neutral ferric chloride solution?
1. (1)Threonine
2. (2)Serine
3. (3)Tyrosine
4. (4)Cysteine

	List-I		List-II
	Vitamin		Name
A.	Vitamin B $_1$	I.	Pyridoxine
B.	Vitamin B $_2$	II.	Ascorbic acid
C.	Vitamin B $_6$	III.	Thiamine
D.	Vitamin C	IV.	Riboflavin

	List-I		List-II
	Name of		One letter
	amino acid		symbol/type)
A	Arginine	I.	D / Non-essential
B	Aspartic acid	II.	R / Essential
C	Lysine	III.	E / Non-essential
D	Glutamic acid	IV.	K/Essential

List-I		List-II
Deficiency Disease		Vitamin
A.	Scurvy	I.	Pyridoxine
B.	Convulsions	II.	Vitamin A
C.	Cheilosis	III.	Ascorbic Acid
D.	Xerophthalmia	IV.	Riboflavin

(Y)	(Sequence)
Threonine	Ser – Thr – Asp – Gly – Ala

(Y)	(Sequence)
Serine	Thr – Ser – Asp – Ala – Gly

(Y)	(Sequence)
Threonine	Thr – Ser – Asp – Gly – Ala

(Y)	(Sequence)
Serine	Ser – Asp – Thr – Ala – Gly