JEE Main Previous Year Questions (2025): Biomolecules

 Page 1


T : 1 Q he total number of hydrogen bonds of a DNA-double Helix strand
whose one strand has the following sequence of bases is ________.
JEE Main 2025 (Online) 4th April Morning Shift
Ans: 33
Solution:
Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.
Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.
In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine
and thymine base which will form total 12 H -bonds with other DNA strand.
Total no. of H bonds 
Ans. 33
W : 3 2 Q hich of the following acids is a vitamin ?
JEE Main 2025 (Online) 22nd January Morning Shift
5 ' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' 5 ' G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' = 7 × 3 + 6 × 2 = 3 3
Page 2


T : 1 Q he total number of hydrogen bonds of a DNA-double Helix strand
whose one strand has the following sequence of bases is ________.
JEE Main 2025 (Online) 4th April Morning Shift
Ans: 33
Solution:
Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.
Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.
In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine
and thymine base which will form total 12 H -bonds with other DNA strand.
Total no. of H bonds 
Ans. 33
W : 3 2 Q hich of the following acids is a vitamin ?
JEE Main 2025 (Online) 22nd January Morning Shift
5 ' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' 5 ' G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' = 7 × 3 + 6 × 2 = 3 3 Options:
A. Saccharic acid
B. Ascorbic acid
C. Aspartic acid
D. Adipic acid
Ans: B
Solution:
Correct Answer: Ascorbic Acid
Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily
functions, including:
Antioxidant Function: It helps protect cells from damage caused by free radicals.
Collagen Synthesis: It is crucial for the formation of collagen, a protein necessary for skin, cartilage,
tendons, ligaments, and blood vessels.
Immune Support: It supports the immune system by enhancing the body's natural defenses.
Iron Absorption: It improves the absorption of non-heme iron from plant-based foods.
Among the given options, only ascorbic acid qualifies as a vitamin.
I : 3 Q dentify the number of structure/s from the following which can be
corelated to D-glyceraldehyde.
JEE Main 2025 (Online) 22nd January Evening Shift
Page 3


T : 1 Q he total number of hydrogen bonds of a DNA-double Helix strand
whose one strand has the following sequence of bases is ________.
JEE Main 2025 (Online) 4th April Morning Shift
Ans: 33
Solution:
Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.
Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.
In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine
and thymine base which will form total 12 H -bonds with other DNA strand.
Total no. of H bonds 
Ans. 33
W : 3 2 Q hich of the following acids is a vitamin ?
JEE Main 2025 (Online) 22nd January Morning Shift
5 ' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' 5 ' G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' = 7 × 3 + 6 × 2 = 3 3 Options:
A. Saccharic acid
B. Ascorbic acid
C. Aspartic acid
D. Adipic acid
Ans: B
Solution:
Correct Answer: Ascorbic Acid
Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily
functions, including:
Antioxidant Function: It helps protect cells from damage caused by free radicals.
Collagen Synthesis: It is crucial for the formation of collagen, a protein necessary for skin, cartilage,
tendons, ligaments, and blood vessels.
Immune Support: It supports the immune system by enhancing the body's natural defenses.
Iron Absorption: It improves the absorption of non-heme iron from plant-based foods.
Among the given options, only ascorbic acid qualifies as a vitamin.
I : 3 Q dentify the number of structure/s from the following which can be
corelated to D-glyceraldehyde.
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. three
B. two
C. one
D. four
Ans: A
Solution:
In  group in right hand side then D-configuration is assigned. A , B , D - O H G : 4 Q iven below are two statements:
Page 4


T : 1 Q he total number of hydrogen bonds of a DNA-double Helix strand
whose one strand has the following sequence of bases is ________.
JEE Main 2025 (Online) 4th April Morning Shift
Ans: 33
Solution:
Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.
Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.
In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine
and thymine base which will form total 12 H -bonds with other DNA strand.
Total no. of H bonds 
Ans. 33
W : 3 2 Q hich of the following acids is a vitamin ?
JEE Main 2025 (Online) 22nd January Morning Shift
5 ' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' 5 ' G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' = 7 × 3 + 6 × 2 = 3 3 Options:
A. Saccharic acid
B. Ascorbic acid
C. Aspartic acid
D. Adipic acid
Ans: B
Solution:
Correct Answer: Ascorbic Acid
Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily
functions, including:
Antioxidant Function: It helps protect cells from damage caused by free radicals.
Collagen Synthesis: It is crucial for the formation of collagen, a protein necessary for skin, cartilage,
tendons, ligaments, and blood vessels.
Immune Support: It supports the immune system by enhancing the body's natural defenses.
Iron Absorption: It improves the absorption of non-heme iron from plant-based foods.
Among the given options, only ascorbic acid qualifies as a vitamin.
I : 3 Q dentify the number of structure/s from the following which can be
corelated to D-glyceraldehyde.
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. three
B. two
C. one
D. four
Ans: A
Solution:
In  group in right hand side then D-configuration is assigned. A , B , D - O H G : 4 Q iven below are two statements:
Statement I: Fructose does not contain an aldehydic group but still
reduces Tollen's reagent
Statement II: In the presence of base, fructose undergoes
rearrangement to give glucose.
In the light of the above statements, choose the correct answer from
the options given below
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. Statement I is true but Statement II is false
B. Statement I is false but Statement II is true
C. Both Statement I and Statement II are true
D. Both Statement I and Statement II are false
Ans: C
Solution:
Page 5


T : 1 Q he total number of hydrogen bonds of a DNA-double Helix strand
whose one strand has the following sequence of bases is ________.
JEE Main 2025 (Online) 4th April Morning Shift
Ans: 33
Solution:
Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.
Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.
In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine
and thymine base which will form total 12 H -bonds with other DNA strand.
Total no. of H bonds 
Ans. 33
W : 3 2 Q hich of the following acids is a vitamin ?
JEE Main 2025 (Online) 22nd January Morning Shift
5 ' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' 5 ' G - G - C - A - A - A - T - C - G - G - C - T - A - 3 ' = 7 × 3 + 6 × 2 = 3 3 Options:
A. Saccharic acid
B. Ascorbic acid
C. Aspartic acid
D. Adipic acid
Ans: B
Solution:
Correct Answer: Ascorbic Acid
Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily
functions, including:
Antioxidant Function: It helps protect cells from damage caused by free radicals.
Collagen Synthesis: It is crucial for the formation of collagen, a protein necessary for skin, cartilage,
tendons, ligaments, and blood vessels.
Immune Support: It supports the immune system by enhancing the body's natural defenses.
Iron Absorption: It improves the absorption of non-heme iron from plant-based foods.
Among the given options, only ascorbic acid qualifies as a vitamin.
I : 3 Q dentify the number of structure/s from the following which can be
corelated to D-glyceraldehyde.
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. three
B. two
C. one
D. four
Ans: A
Solution:
In  group in right hand side then D-configuration is assigned. A , B , D - O H G : 4 Q iven below are two statements:
Statement I: Fructose does not contain an aldehydic group but still
reduces Tollen's reagent
Statement II: In the presence of base, fructose undergoes
rearrangement to give glucose.
In the light of the above statements, choose the correct answer from
the options given below
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. Statement I is true but Statement II is false
B. Statement I is false but Statement II is true
C. Both Statement I and Statement II are true
D. Both Statement I and Statement II are false
Ans: C
Solution:
T : 5 Q he -Helix and  - Pleated sheet structures of protein are
associated with its :
JEE Main 2025 (Online) 23rd January Evening Shift
Options:
A. tertiary structure
B. quaternary structure
C. primary structure
D. secondary structure
Ans: D
Solution:
-helix and -pleated sheet belongs to secondary structure of protein, which have hydrogen bonds.
a ß a ß T : 6 Q he carbohydrate "Ribose" present in DNA, is
A. A pentose sugar
B. present in pyranose from
C. in "D" configuration
D. a reducing sugar, when free