Given below are two statements:
Statement I: D-(+)-glucose + D-(+)-fructose -H₂O sucrose sucrose Hydrolysis D-(+)-glucose + D-(+)-fructose$\text{D-(+)-glucose} + \text{D-(+)-fructose} \xrightarrow{-\mathrm{H}_2\mathrm{O}} \text{sucrose} \qquad \text{sucrose} \xrightarrow{\text{Hydrolysis}} \text{D-(+)-glucose} + \text{D-(+)-fructose}$
Statement II: Invert sugar is formed during sucrose hydrolysis.
In the light of given statements, choose the correct answer from the options given below:
A.Both Statement I and Statement II are true.$\text{Both Statement I and Statement II are true.}$
B.Statement I is false but Statement II is true.$\text{Statement I is false but Statement II is true.}$
C.Statement I is true but Statement II is false.$\text{Statement I is true but Statement II is false.}$
D.Both Statement I and Statement II are false.$\text{Both Statement I and Statement II are false.}$
Solution & Explanation
Core Logic
Statement I: Sucrose is formed by condensation of D-(+)-glucose$\text{D-(+)-glucose}$ and D-(-)-fructose$\text{D-(-)-fructose}$ (levorotatory fructose, not dextrorotatory as claimed). Hydrolysis of sucrose yields D-(+)-glucose$\text{D-(+)-glucose}$ and D-(-)-fructose$\text{D-(-)-fructose}$. Thus, Statement I is false.
Statement II: Hydrolysis of dextrorotatory sucrose (+66.5°$+66.5^{\circ}$) yields a mixture of dextrorotatory glucose (+52.5°$+52.5^{\circ}$) and highly levorotatory fructose (-92.4°$-92.4^{\circ}$). Because the overall specific rotation of the mixture becomes levorotatory (-39.9°$-39.9^{\circ}$), the hydrolyzed mixture is called invert sugar. Thus, Statement II is true.
Pattern Recognition
Natural fructose is always levorotatory, D-(-)-fructose$\text{D-(-)-fructose}$. Dextrorotatory fructose mentioned in Statement I is an immediate giveaway that the statement is false.
Keywords:#Sucrose hydrolysis products#JEE Main 2025 Morning Q43#Invert sugar specific rotation#Dextrorotatory vs levorotatory sugars
More Biomolecules Previous-Year Questions — Page 5
Q50jee_main_2025_04_april_morningNucleic Acids
The total number of hydrogen bonds of a DNA-double Helix strand whose one strand has the following sequence of bases is:
5' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3'$$5' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3'$$
Numerical Answer.Answer: 33 to 33
Solution
Related Formula
G-C base pairing 3 Hydrogen bonds$$\text{G-C base pairing} \implies 3 \text{ Hydrogen bonds}$$A-T base pairing 2 Hydrogen bonds$$\text{A-T base pairing} \implies 2 \text{ Hydrogen bonds}$$
Core Logic
Let's audit the nucleotide base distribution across the given single strand structure:
5' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3'$$5' - G - G - C - A - A - A - T - C - G - G - C - T - A - 3'$$
Count the Guanine (G) and Cytosine (C) bases:
Bases present: G₁, G₂, C₃, C₈, G₉, G₁₀, C₁₁$G_1, G_2, C_3, C_8, G_9, G_{10}, C_{11}$$\implies$ Total of 7 bases.
Each G-C interaction forms 3 hydrogen bonds:
Q26jee_main_2025_07_april_eveningProteins and Amino Acids
Given below are two statements:
Statement (I): On hydrolysis, oligo peptides give rise to fewer number of α$\alpha$-amino acids while proteins give rise to a large number of β$\beta$-amino acids.
Statement (II): Natural proteins are denatured by acids which convert the water soluble form of fibrous proteins to their water insoluble form.
In the light of the above statements, choose the most appropriate answer from the options given below:
A.Both statement I and statement II are correct$\text{Both statement I and statement II are correct}$
B.Statement I is incorrect but Statement II is correct$\text{Statement I is incorrect but Statement II is correct}$
C.Both statement I and statement II are incorrect$\text{Both statement I and statement II are incorrect}$
D.Statement I is correct but Statement II is incorrect$\text{Statement I is correct but Statement II is incorrect}$
Statement (I) is incorrect because the complete hydrolysis of both oligopeptides and proteins yields α$\alpha$-amino acids, not β$\beta$-amino acids.
Statement (II) is incorrect because fibrous proteins are inherently water-insoluble structural materials. Denaturation typically disrupts the tertiary and secondary structures of water-soluble globular proteins, making them insoluble.
Step 1: Final Conclusion
Since both Statement I and Statement II are false, option (3) is the correct choice.
Pattern Recognition
All naturally occurring proteins are polymers of α$\alpha$-amino acids, so any statement mentioning β$\beta$-amino acids as direct translation products can be confidently ruled out. Fibrous proteins (like keratin or collagen) are structural and always insoluble, unlike globular proteins.
Chapter Mix
Class 12 Chemistry: Biomolecules
Q44jee_main_2025_24_jan_eveningStructure of Nucleic Acids
Match List-I with List-II tracking nitrogenous bases structures:
List-I (Base)
List-II (Chemical Structure Diagram)
(A) Adenine
(I) The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.
(B) Cytosine
(II) The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.
(C) Thymine
(III) The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.
(D) Uracil
(IV) The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.
Choose the correct answer from the options given below :
A. \text{(A)-(III), (B)-(IV), (C)-(II), (D)-(I)}
B. \text{(A)-(III), (B)-(I), (C)-(IV), (D)-(II)}
C. \text{(A)-(IV), (B)-(III), (C)-(II), (D)-(I)}
D. \text{(A)-(III), (B)-(IV), (C)-(I), (D)-(II)}
Solution
Core Logic
Let's identify the chemical structures of the nitrogenous bases used in nucleic acids:
* (A) Adenine: A purine derivative featuring a characteristic fused bicyclic ring system with an amino substituent at position 6 (6-aminopurine) arrow$\rightarrow$(III).
* (B) Cytosine: A pyrimidine monocyclic derivative with an amino group at position 4 and a carbonyl group at position 2 (4-amino-2-oxo-pyrimidine) arrow$\rightarrow$(IV).
* (C) Thymine: Found in DNA, this pyrimidine derivative features a methyl substituent at position 5 along with carbonyl groups at positions 2 and 4 (5-methyl-2,4-dioxo-pyrimidine) arrow$\rightarrow$(II).
* (D) Uracil: Found in RNA, this pyrimidine derivative lacks the methyl group found in thymine, featuring just carbonyl groups at positions 2 and 4 (2,4-dioxo-pyrimidine) arrow$\rightarrow$(I).
Matching these structures gives the sequence: (A)-(III), (B)-(IV), (C)-(II), (D)-(I).
Step-by-Step Structural Validation
The biochemical structures correspond to the following configurations:
The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.The Match List contains nitrogenous bases aligned with their corresponding biochemical molecular ring structures.
Pattern Recognition
Quick identification keys:
Bicyclic ring = Adenine
Monocyclic ring with a -CH₃$-\mathrm{CH}_3$ group = Thymine
Monocyclic ring without a -CH₃$-\mathrm{CH}_3$ group = Uracil
Monocyclic ring with an amino group (-NH₂$-\mathrm{NH}_2$) = Cytosine
The carbohydrates "Ribose" present in DNA, is
A. A pentose sugar
B. present in pyranose from
C. in "D" configuration
D. a reducing sugar, when free
E. in α$\alpha$ -anomeric form
Choose the correct answer from the options given below:
A. A, C and D Only
B. A, B and E Only
C. B, D and E Only
D. A, D and E Only
Solution
Core Logic
The specific carbohydrate residue present across backbone units in DNA molecules is β$\beta$-2-deoxy-D-ribose.
Its spatial parameters satisfy the following conditions:
It is a 5-carbon pentose sugars skeleton structure (A).
It maintains a canonical D configuration pathway sequence (C).
When localized in free, open unlinked molecular solutions, it standardly functions as a reducing carbohydrate assembly agent (D).
It exists predominantly in a furanose cycle form inside DNA, rather than a pyranose ring. Carbohydrates - Nucleic Acids component diagram for Q36 - JEE Main 2025 Morning
Pattern Recognition
Ribose in nucleic acids occurs primarily as a five-membered furanose ring configuration system.
Chapter Mix
Class 12 Chemistry: Biomolecules
Q28jee_main_2025_28_jan_eveningCarbohydrates and Glycosidic Linkages
Match List-I with List-II
List-I (Saccharides)
List-II (Glycosidic-linkages found)
(A) Sucrose
(I) α 1-4$\alpha\text{ 1-4}$
(B) Maltose
(II) α 1-4 and α 1-6$\alpha\text{ 1-4 and }\alpha\text{ 1-6}$
(C) Lactose
(III) α 1 - β 2$\alpha\text{ 1 - }\beta\text{ 2}$
(D) Amylopectin
(IV) β 1-4$\beta\text{ 1-4}$
Choose the correct answer from the options given below :
Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.