JEE Advanced Previous Year Questions (2021 - 2025): Biomolecules

 Page 1


 
Q1:  For a double strand DNA, one strand is given below:
The amount of energy required to split the double strand DNA into two single strands is ______ kcal mol ?¹.
[Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol ?¹, G-C base pair = 1.5 kcal mol ?¹, and A-U
base pair = 1.25 kcal mol ?¹. Ignore electrostatic repulsion between the phosphate groups.]       [JEE Advanced
2024 Paper 2]
Ans: 41
A = T ? 2 H-bond
G = C ? 3 H-bond
Number of A = T pair = 7
Number of G = C pair = 6
Number of H-bond involved in A = T = 7 × 2 = 14
Number of H-bond involved in G = C = 6 × 3 = 18
Energy required for A = T = 14 × 1 = 14
Energy required for G = C = 18 × 1.5 = 27
T otal energy required = 14 + 27 = 41
Page 2


 
Q1:  For a double strand DNA, one strand is given below:
The amount of energy required to split the double strand DNA into two single strands is ______ kcal mol ?¹.
[Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol ?¹, G-C base pair = 1.5 kcal mol ?¹, and A-U
base pair = 1.25 kcal mol ?¹. Ignore electrostatic repulsion between the phosphate groups.]       [JEE Advanced
2024 Paper 2]
Ans: 41
A = T ? 2 H-bond
G = C ? 3 H-bond
Number of A = T pair = 7
Number of G = C pair = 6
Number of H-bond involved in A = T = 7 × 2 = 14
Number of H-bond involved in G = C = 6 × 3 = 18
Energy required for A = T = 14 × 1 = 14
Energy required for G = C = 18 × 1.5 = 27
T otal energy required = 14 + 27 = 41
 
 
 JEE Advanced 2023 Paper 2 Online 
Q1. A disaccharide ?? cannot be oxidised by bromine water. The acid hydrolysis of ?? 
leads to a laevorotatory solution. The disaccharide ?? is : 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (a) 
A and D cannot be oxidised by bromine water as they do not have hemiacetal linkage. 
Page 3


 
Q1:  For a double strand DNA, one strand is given below:
The amount of energy required to split the double strand DNA into two single strands is ______ kcal mol ?¹.
[Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol ?¹, G-C base pair = 1.5 kcal mol ?¹, and A-U
base pair = 1.25 kcal mol ?¹. Ignore electrostatic repulsion between the phosphate groups.]       [JEE Advanced
2024 Paper 2]
Ans: 41
A = T ? 2 H-bond
G = C ? 3 H-bond
Number of A = T pair = 7
Number of G = C pair = 6
Number of H-bond involved in A = T = 7 × 2 = 14
Number of H-bond involved in G = C = 6 × 3 = 18
Energy required for A = T = 14 × 1 = 14
Energy required for G = C = 18 × 1.5 = 27
T otal energy required = 14 + 27 = 41
 
 
 JEE Advanced 2023 Paper 2 Online 
Q1. A disaccharide ?? cannot be oxidised by bromine water. The acid hydrolysis of ?? 
leads to a laevorotatory solution. The disaccharide ?? is : 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (a) 
A and D cannot be oxidised by bromine water as they do not have hemiacetal linkage. 
The acid hydrolysis of A leads to a laevorotatory solution. 
A is sucrose which is dextrorotatory, on acid hydrolysis gives mixture of alpha-D-glucose and 
beta-D-fructose, the mixture is laevorotatory 
 
2022 
 
JEE Advanced 2022 Paper 2 Online 
Q1: Treatment of D-glucose with aqueous ?? ?? ?? ?? results in a mixture of 
monosaccharides, which are 
A. 
 
B. 
 
C. 
 
D. 
 
Page 4


 
Q1:  For a double strand DNA, one strand is given below:
The amount of energy required to split the double strand DNA into two single strands is ______ kcal mol ?¹.
[Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol ?¹, G-C base pair = 1.5 kcal mol ?¹, and A-U
base pair = 1.25 kcal mol ?¹. Ignore electrostatic repulsion between the phosphate groups.]       [JEE Advanced
2024 Paper 2]
Ans: 41
A = T ? 2 H-bond
G = C ? 3 H-bond
Number of A = T pair = 7
Number of G = C pair = 6
Number of H-bond involved in A = T = 7 × 2 = 14
Number of H-bond involved in G = C = 6 × 3 = 18
Energy required for A = T = 14 × 1 = 14
Energy required for G = C = 18 × 1.5 = 27
T otal energy required = 14 + 27 = 41
 
 
 JEE Advanced 2023 Paper 2 Online 
Q1. A disaccharide ?? cannot be oxidised by bromine water. The acid hydrolysis of ?? 
leads to a laevorotatory solution. The disaccharide ?? is : 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (a) 
A and D cannot be oxidised by bromine water as they do not have hemiacetal linkage. 
The acid hydrolysis of A leads to a laevorotatory solution. 
A is sucrose which is dextrorotatory, on acid hydrolysis gives mixture of alpha-D-glucose and 
beta-D-fructose, the mixture is laevorotatory 
 
2022 
 
JEE Advanced 2022 Paper 2 Online 
Q1: Treatment of D-glucose with aqueous ?? ?? ?? ?? results in a mixture of 
monosaccharides, which are 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (C) 
 
 
 
 
 
 
 
Page 5


 
Q1:  For a double strand DNA, one strand is given below:
The amount of energy required to split the double strand DNA into two single strands is ______ kcal mol ?¹.
[Given: Average energy per H-bond for A-T base pair = 1.0 kcal mol ?¹, G-C base pair = 1.5 kcal mol ?¹, and A-U
base pair = 1.25 kcal mol ?¹. Ignore electrostatic repulsion between the phosphate groups.]       [JEE Advanced
2024 Paper 2]
Ans: 41
A = T ? 2 H-bond
G = C ? 3 H-bond
Number of A = T pair = 7
Number of G = C pair = 6
Number of H-bond involved in A = T = 7 × 2 = 14
Number of H-bond involved in G = C = 6 × 3 = 18
Energy required for A = T = 14 × 1 = 14
Energy required for G = C = 18 × 1.5 = 27
T otal energy required = 14 + 27 = 41
 
 
 JEE Advanced 2023 Paper 2 Online 
Q1. A disaccharide ?? cannot be oxidised by bromine water. The acid hydrolysis of ?? 
leads to a laevorotatory solution. The disaccharide ?? is : 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (a) 
A and D cannot be oxidised by bromine water as they do not have hemiacetal linkage. 
The acid hydrolysis of A leads to a laevorotatory solution. 
A is sucrose which is dextrorotatory, on acid hydrolysis gives mixture of alpha-D-glucose and 
beta-D-fructose, the mixture is laevorotatory 
 
2022 
 
JEE Advanced 2022 Paper 2 Online 
Q1: Treatment of D-glucose with aqueous ?? ?? ?? ?? results in a mixture of 
monosaccharides, which are 
A. 
 
B. 
 
C. 
 
D. 
 
Ans: (C) 
 
 
 
 
 
 
 
2021 
JEE Advanced 2021 Paper 1 Online 
MCQ (More than One Correct Answer) 
Q1: Given : 
 
The compound(s), which on reaction with ?? ?? ?? ?? will give the product having degree of 
rotation, [ ?? ]
?? = - ???? . ?? °
 is (are) 
A. 
 
B.