Biomolecules: JEE Main Previous Year Questions (2021-2026)

 Page 1


JEE Main Previous Year Questions (2021-2026): 
Biomolecules  
 
(January 2026) 
 
Q1: Structures of four disaccharides are given below. Among the given disaccharides, 
the non-reducing sugar is: 
A:  
B:  
Page 2


JEE Main Previous Year Questions (2021-2026): 
Biomolecules  
 
(January 2026) 
 
Q1: Structures of four disaccharides are given below. Among the given disaccharides, 
the non-reducing sugar is: 
A:  
B:  
C:  
D:  
Answer: A 
Explanation:  
Structure (1) given is of sucrose which is non reducing. 
 
For non reducing sugar compound should have acetal linkage not hemi acetal linkage. 
 
 
Q2: 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: 
A:  
Page 3


JEE Main Previous Year Questions (2021-2026): 
Biomolecules  
 
(January 2026) 
 
Q1: Structures of four disaccharides are given below. Among the given disaccharides, 
the non-reducing sugar is: 
A:  
B:  
C:  
D:  
Answer: A 
Explanation:  
Structure (1) given is of sucrose which is non reducing. 
 
For non reducing sugar compound should have acetal linkage not hemi acetal linkage. 
 
 
Q2: 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: 
A:  
B:  
C:  
D:  
Answer: D  
Explanation: 
 
 
Q3: 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: 
A: 8 
B: 3 
C: 4 
D: 6 
Answer: D 
Explanation:  
Page 4


JEE Main Previous Year Questions (2021-2026): 
Biomolecules  
 
(January 2026) 
 
Q1: Structures of four disaccharides are given below. Among the given disaccharides, 
the non-reducing sugar is: 
A:  
B:  
C:  
D:  
Answer: A 
Explanation:  
Structure (1) given is of sucrose which is non reducing. 
 
For non reducing sugar compound should have acetal linkage not hemi acetal linkage. 
 
 
Q2: 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: 
A:  
B:  
C:  
D:  
Answer: D  
Explanation: 
 
 
Q3: 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: 
A: 8 
B: 3 
C: 4 
D: 6 
Answer: D 
Explanation:  
Gly ala val 
Gly val ala 
Val gly ala 
Val ala gly 
Ala val gly 
Ala gly val 
Total tri peptides = 6 
 
Q4: Both human DNA and RNA are chiral molecules. The chirality in DNA and RNA arises 
due to the presence of 
A: L-sugar component 
B: D-sugar component 
C: Chiral phosphate unit 
D: Base unit 
Answer: B 
Explanation:  
DNA and RNA show chirality because they contain a chiral sugar in their structure. 
In DNA, the sugar present is chiral 2-deoxy-Ribose. 
In RNA, the sugar present is chiral Ribose. 
 
Q5: Match List - I with List - II. 
 
Choose the correct answer from the options given below: 
A: A-IV, B-III, C-II, D-I 
B: A-I, B-III, C-IV, D-II 
C: A-III, B-I, C-IV, D-II 
D: A-IV, B-I, C-II, D-III 
Answer: D 
Page 5


JEE Main Previous Year Questions (2021-2026): 
Biomolecules  
 
(January 2026) 
 
Q1: Structures of four disaccharides are given below. Among the given disaccharides, 
the non-reducing sugar is: 
A:  
B:  
C:  
D:  
Answer: A 
Explanation:  
Structure (1) given is of sucrose which is non reducing. 
 
For non reducing sugar compound should have acetal linkage not hemi acetal linkage. 
 
 
Q2: 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: 
A:  
B:  
C:  
D:  
Answer: D  
Explanation: 
 
 
Q3: 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: 
A: 8 
B: 3 
C: 4 
D: 6 
Answer: D 
Explanation:  
Gly ala val 
Gly val ala 
Val gly ala 
Val ala gly 
Ala val gly 
Ala gly val 
Total tri peptides = 6 
 
Q4: Both human DNA and RNA are chiral molecules. The chirality in DNA and RNA arises 
due to the presence of 
A: L-sugar component 
B: D-sugar component 
C: Chiral phosphate unit 
D: Base unit 
Answer: B 
Explanation:  
DNA and RNA show chirality because they contain a chiral sugar in their structure. 
In DNA, the sugar present is chiral 2-deoxy-Ribose. 
In RNA, the sugar present is chiral Ribose. 
 
Q5: Match List - I with List - II. 
 
Choose the correct answer from the options given below: 
A: A-IV, B-III, C-II, D-I 
B: A-I, B-III, C-IV, D-II 
C: A-III, B-I, C-IV, D-II 
D: A-IV, B-I, C-II, D-III 
Answer: D 
Explanation:  
 
Q6: 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 : 
A: Both Statement I and Statement II are false 
B: Both Statement I and Statement II are true 
C: Statement I is true but Statement II is false 
D: Statement I is false but Statement II is true 
Answer: C 
Explanation: 
 
 
? Sucrose is dextrorotatory and hydrolysed product is laevorotatory. 
 
Q7: The correct statements are: