Complete Biomolecules Package

Biomolecules – Complete Board-Focused Notes (GSEB HSC)

1. Carbohydrates
Definition: Polyhydroxy aldehydes or ketones, or compounds
which produce them on hydrolysis.
General Formula: C_n(H_2_n
Classification:
1. Monosaccharides – Simple sugars, cannot be hydrolysed
further.
Examples: Glucose, Fructose.
Aldose: Aldehyde group (Glucose)
Ketose: Ketone group (Fructose)
2. Oligosaccharides – 2–10 monosaccharide units.
Examples:
Disaccharides: Sucrose (Glucose + Fructose), Lactose (Glucose +
Galactose), Maltose (Glucose + Glucose).
3. Polysaccharides – Many monosaccharide units.
Examples: Starch, Cellulose, Glycogen.
Reducing vs Non-reducing sugars:
Reducing sugars: Contain free aldehyde/ketone group (Glucose,
Lactose, Maltose).
Non-reducing sugars: No free aldehyde/ketone group (Sucrose).
Tests:
Molisch test: General carbohydrate test (purple ring).
Fehling’s/Benedict’s test: Reducing sugar test (red ppt).
Important points for MCQs:
Starch → Amylose (linear, α-1,4) + Amylopectin (branched, α-1,6).
Cellulose → β-1,4 linkages, cannot be digested by humans.
Glycogen → Highly branched, animal storage polysaccharide.
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2. Proteins
Definition: Polymers of α-amino acids linked by peptide bonds.
Levels of Structure:
1. Primary: Sequence of amino acids.
2. Secondary: α-helix, β-pleated sheet (H-bonds).
3. Tertiary: 3D folding (disulfide bonds, H-bonds, hydrophobic
interactions).
4. Quaternary: Arrangement of multiple polypeptide chains (e.g.,
Hemoglobin).
Types:
Fibrous proteins: Structural, insoluble (Keratin, Collagen).
Globular proteins: Functional, soluble (Enzymes, Hemoglobin).
Denaturation: Loss of biological activity due to unfolding (e.g.,
egg white cooking).
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3. Enzymes
Definition: Biological catalysts, mostly proteins.
Specificity: Highly substrate-specific.
Nomenclature: Suffix -ase (except pepsin, trypsin).
Mechanism: Enzyme-Substrate complex → product.
Factors affecting activity:
Temperature, pH, substrate concentration, inhibitors.
Cofactors:
Prosthetic group (tightly bound), Coenzyme (loosely bound), Metal
activators.
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4. Vitamins
Definition: Organic compounds needed in small amounts for
normal growth & metabolism.
Classification:
Fat-soluble: A, D, E, K – stored in liver & fat.
Water-soluble: B-complex, C – excreted in urine, not stored.
Deficiency diseases:
Vit A → Night blindness.
Vit D → Rickets.
Vit E → Reproductive disorders.
Vit K → Blood clotting issues.
Vit C → Scurvy.
Vit B_1 → Beriberi.
Vit B_2 → Cheilosis.
Vit B_3 → Pellagra.
Vit B_6 → Convulsions.
Vit B_{12} → Pernicious anemia.
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5. Nucleic Acids
Definition: Biopolymers controlling heredity & protein synthesis.
Types: DNA & RNA.
Nucleoside: Base + sugar.
Nucleotide: Base + sugar + phosphate.
Nitrogenous Bases:
Purines: Adenine, Guanine.
Pyrimidines: Cytosine, Thymine (DNA), Uracil (RNA).
DNA: Double helix (Watson-Crick model).
Base pairing: A=T (2 H-bonds), G≡C (3 H-bonds).
RNA types: mRNA, tRNA, rRNA.
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6. Hormones
Definition: Chemical messengers secreted by endocrine glands.
Examples: Insulin (protein), Adrenaline (amine), Steroid hormones
(estrogen, testosterone).
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High-Yield Diagram List for MCQs
1. Open chain & cyclic structure of glucose.
2. Structure of α-D-glucopyranose.
3. Structure of sucrose, lactose, maltose.
4. α-helix and β-pleated sheet diagram.
5. DNA double helix with base pairing.
6. General structure of nucleotide.

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📚 Class 12 Chemistry – Biomolecules Notes (Board + MCQ Focus)
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1. Carbohydrates
Definition: Polyhydroxy aldehydes or ketones (or substances that
give these on hydrolysis).
General formula: C_n(H₂O) (not valid for all).
Classification
(A) Monosaccharides (can’t be hydrolysed):
Trioses: Glyceraldehyde, Dihydroxyacetone.
Pentoses: Ribose, Deoxyribose.
Hexoses: Glucose, Fructose.
(B) Oligosaccharides (2–10 monosaccharides):
Disaccharides: Sucrose (α-D-glucose + β-D-fructose), Maltose (α-
D-glucose + α-D-glucose), Lactose (β-D-galactose + β-D-glucose).
(C) Polysaccharides (>10 units):
Starch (plants, α-glucose).
Glycogen (animals, α-glucose, highly branched).
Cellulose (plants, β-glucose, straight chain).
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Glucose
Sources: Grapes, honey.
Open-chain formula: Aldohexose.
Cyclic forms: α-D-glucopyranose, β-D-glucopyranose (formed via
hemiacetal linkage between C1 and C5 OH).
Mutarotation: Change in optical rotation due to interconversion
between α and β forms in aqueous solution.
Test positive for: Tollen’s, Fehling’s (due to –CHO).
---
Fructose
Source: Honey, fruits.
Structure: Ketohexose.
Cyclic forms: α-D-fructofuranose, β-D-fructofuranose.
Test positive for: Tollen’s, Fehling’s (after tautomerisation in
alkaline medium).
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Important Reactions of Glucose
1. Acetylation: Glucose + Ac₂O → Glucose pentaacetate.
2. Oxidation:
Mild: Gluconic acid.
Strong: Saccharic acid.
3. Reduction: Glucitol (sorbitol).
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2. Proteins
Definition: Polymers of α-amino acids linked by peptide bonds.
Structure levels:
1. Primary – sequence of amino acids.
2. Secondary – α-helix, β-pleated sheet (H-bonds).
3. Tertiary – 3D folding (disulfide bonds, ionic bonds).
4. Quaternary – more than one polypeptide chain.
Amino acids:
General formula: NH₂–CH(R)–COOH.
Types: Essential (must be taken in diet) & Non-essential (made in
body).
Zwitter ion: Contains both +ve (–NH₃⁺) and –ve (–COO⁻) charges
at isoelectric point.
---
3. Enzymes
Nature: Mostly globular proteins.
Function: Biological catalysts, specific for substrate.
Factors affecting activity: pH, temperature, substrate
concentration.
Examples: Amylase, Invertase, Pepsin.
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4. Vitamins
Fat-soluble: A, D, E, K (stored in liver, not excreted easily).
Water-soluble: B-complex, C (excreted in urine).
Deficiency diseases:
A → Night blindness.
D → Rickets.
C → Scurvy.
K → Prolonged blood clotting.
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5. Nucleic Acids
Monomers: Nucleotides = Nitrogen base + Sugar + Phosphate.
Types:
DNA: Deoxyribose, bases A, G, C, T.
RNA: Ribose, bases A, G, C, U.
Functions:
DNA – genetic information storage.
RNA – protein synthesis (mRNA, tRNA, rRNA).
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6. Hormones
Definition: Chemical messengers secreted by endocrine glands.
Examples: Insulin (protein), Adrenaline (amine), Thyroxine
(iodinated amino acid derivative).
---
🔥 Quick MCQ Triggers
Sucrose is non-reducing because no free –CHO or –C=O.
Cellulose: β(1→4) glycosidic bonds.
α-helix: Right-handed coil.
Vitamin K: Blood clotting.
DNA base pair rule: A=T (2 H-bonds), G≡C (3 H-bonds).

--- MCQ Section -----

1. Carbohydrates (25 MCQs)

1. Which of the following is a disaccharide?

A. Glucose
B. Fructose
C. Maltose
D. Galactose
Answer: C

2. Which of the following is a ketose sugar?

A. Glucose
B. Fructose
C. Galactose
D. Mannose
Answer: B

3. Which carbohydrate does not reduce Tollen’s reagent?

A. Glucose
B. Fructose
C. Sucrose
D. Maltose
Answer: C

4. In glucose, the number of chiral carbon atoms is:

A. 4
B. 5
C. 6
D. 3
Answer: A

5. Which is the storage polysaccharide in animals?

A. Starch
B. Cellulose
C. Glycogen
D. Chitin
Answer: C

6. Which of the following is a pentose sugar?

A. Ribose
B. Glucose
C. Maltose
D. Galactose
Answer: A

7. The bond connecting monosaccharide units in disaccharides is:

A. Peptide bond
B. Glycosidic bond
C. Hydrogen bond
D. Phosphodiester bond
Answer: B

8. Glucose on oxidation with bromine water gives:

A. Gluconic acid
B. Glucaric acid
C. Gluconolactone
D. Sorbitol
Answer: A

9. The cyclic form of glucose is:

A. Pyranose only
B. Furanose only
C. Both pyranose and furanose
D. Neither pyranose nor furanose
Answer: C

10. Which is a homopolysaccharide?

A. Cellulose
B. Starch
C. Glycogen
D. All of these
Answer: D

11. Cellulose is not digested by humans because:

A. No cellulase enzyme
B. Insoluble nature
C. Toxic nature
D. High molecular mass
Answer: A

12. Which sugar is known as invert sugar?

A. Glucose
B. Fructose
C. Sucrose hydrolysis mixture
D. Lactose
Answer: C

13. Which test distinguishes aldoses from ketoses?

A. Fehling’s test
B. Tollen’s test
C. Bial’s test
D. Seliwanoff’s test
Answer: D

14. Which is an example of a reducing sugar?

A. Sucrose
B. Lactose
C. Maltose
D. Both B and C
Answer: D

15. The main structural polysaccharide in plant cell walls is:

A. Cellulose
B. Glycogen
C. Chitin
D. Amylopectin
Answer: A

16. Which form of glucose rotates plane polarised light to the

right?
A. D-(+)-glucose
B. L-(-)-glucose
C. D-(-)-glucose
D. L-(+)-glucose
Answer: A

17. Which sugar is found in RNA?

A. Deoxyribose
B. Ribose
C. Fructose
D. Mannose
Answer: B

18. Starch is made up of:

A. Amylose + Amylopectin
B. Amylopectin + Glycogen
C. Amylose only
D. Cellulose only
Answer: A

19. Which is the sweetest sugar?

A. Glucose
B. Sucrose
C. Fructose
D. Maltose
Answer: C

20. (Diagram-based) Identify the cyclic structure below: (Shows α-

D-glucopyranose ring)
A. α-D-glucopyranose
B. β-D-glucopyranose
C. α-D-fructofuranose
D. β-D-fructofuranose
Answer: A

21. Glucose is converted into fructose in the presence of:

A. Invertase
B. Zymase
C. Glucose isomerase
D. Maltase
Answer: C

22. Which monosaccharide is a component of lactose?

A. Glucose and Galactose
B. Glucose and Fructose
C. Galactose and Fructose
D. Galactose and Mannose
Answer: A

23. The number of monosaccharide units in maltose is:

A. 1
B. 2
C. 3
D. Many
Answer: B

24. Which of the following is an example of a

heteropolysaccharide?
A. Hyaluronic acid
B. Glycogen
C. Amylose
D. Cellulose
Answer: A

25. (Diagram-based) Identify the linkage type in amylopectin:

A. α-1,4 and α-1,6 glycosidic bonds
B. α-1,4 and β-1,4 glycosidic bonds
C. β-1,6 and β-1,4 glycosidic bonds
D. α-1,2 and β-1,2 glycosidic bonds
Answer: A
2. Proteins (20 MCQs)
26. Proteins are polymers of:
A. Nucleotides
B. Amino acids
C. Monosaccharides
D. Fatty acids
Answer: B
27. How many amino acids are commonly found in proteins?
A. 10
B. 20
C. 22
D. 24
Answer: B
28. Which of the following is an essential amino acid?
A. Glycine
B. Alanine
C. Valine
D. Serine
Answer: C
29. The bond between two amino acids is called:
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Disulphide bond
Answer: B
30. The primary structure of a protein refers to:
A. Sequence of amino acids
B. Folding of polypeptide
C. 3D structure of protein
D. Association of multiple polypeptides
Answer: A
31. Which type of protein structure is held by hydrogen bonds
between peptide chains?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: B
32. In α-helix structure, hydrogen bonds form between:
A. CO and NH groups of the same turn
B. CO of one residue and NH of the fourth residue ahead
C. Side chains of amino acids
D. Between peptide bonds and disulphide bridges
Answer: B
33. The tertiary structure of a protein is stabilised by:
A. Hydrogen bonds
B. Ionic interactions
C. Disulphide bridges
D. All of these
Answer: D
34. Which of the following proteins has quaternary structure?
A. Myoglobin
B. Hemoglobin
C. Insulin
D. Pepsin
Answer: B
35. Which amino acid contains a sulphur atom?
A. Glycine
B. Alanine
C. Cysteine
D. Phenylalanine
Answer: C
36. Denaturation of proteins involves:
A. Breaking peptide bonds
B. Loss of primary structure
C. Loss of secondary/tertiary structure
D. Breaking amino acid sequence
Answer: C
37. Which protein is fibrous?
A. Hemoglobin
B. Myoglobin
C. Keratin
D. Albumin
Answer: C
38. Globular proteins are:
A. Soluble in water
B. Insoluble in water
C. Always fibrous
D. Always enzymes
Answer: A
39. Which of the following is a simple protein?
A. Nucleoprotein
B. Chromoprotein
C. Albumin
D. Glycoprotein
Answer: C
40. The amphoteric nature of amino acids is due to the presence
of:
A. -COOH group only
B. -NH₂ group only
C. Both -COOH and -NH₂ groups
D. Side chains
Answer: C
41. Which test detects proteins by purple/violet colour?
A. Biuret test
B. Xanthoproteic test
C. Ninhydrin test
D. Millon’s test
Answer: A
42. Collagen is:
A. Globular protein
B. Fibrous protein
C. Conjugated protein
D. Hormone protein
Answer: B
43. Which amino acid is not optically active?
A. Glycine
B. Alanine
C. Serine
D. Valine
Answer: A
44. (Diagram-based) The given figure shows the arrangement of
polypeptide chains in: (Image of α-helix)
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Answer: A
45. The number of peptide bonds in a tripeptide is:
A. 1
B. 2
C. 3
D. 4
Answer: B
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3. Enzymes (15 MCQs)
46. Enzymes are mostly:
A. Carbohydrates
B. Proteins
C. Lipids
D. Nucleic acids
Answer: B
47. Which of the following is a coenzyme?
A. NAD⁺
B. Mg²⁺
C. Zn²⁺
D. Fe²⁺
Answer: A
48. The enzyme that catalyses the breakdown of starch into
maltose is:
A. Maltase
B. Amylase
C. Lactase
D. Zymase
Answer: B
49. Which factor does NOT affect enzyme activity?
A. Temperature
B. pH
C. Substrate concentration
D. Colour of enzyme
Answer: D
50. Lock and key hypothesis is related to:
A. DNA replication
B. Protein folding
C. Enzyme–substrate interaction
D. Hormone binding
Answer: C
51. Which enzyme catalyses the conversion of sucrose to glucose
+ fructose?
A. Maltase
B. Invertase
C. Zymase
D. Urease
Answer: B
52. The non-protein part of an enzyme is called:
A. Apoenzyme
B. Cofactor
C. Coenzyme
D. Holoenzyme
Answer: B
53. Which of the following is a ribozyme?
A. Pepsin
B. RNase P
C. Amylase
D. Trypsin
Answer: B
54. Enzymes increase the rate of reaction by:
A. Increasing activation energy
B. Lowering activation energy
C. Increasing temperature
D. Changing equilibrium constant
Answer: B
55. Optimum temperature for most enzymes in human body is:
A. 25°C
B. 37°C
C. 50°C
D. 60°C
Answer: B
56. Enzyme activity decreases sharply above optimum
temperature because:
A. Substrate denatures
B. Enzyme denatures
C. Cofactor is lost
D. pH changes
Answer: B
57. Which enzyme catalyses the hydrolysis of urea?
A. Urease
B. Amylase
C. Maltase
D. Lactase
Answer: A
58. The rate of an enzyme reaction can be doubled by:
A. Increasing enzyme concentration
B. Decreasing substrate concentration
C. Decreasing pH below optimum
D. Heating above optimum
Answer: A
59. (Diagram-based) The point at which the enzyme is saturated
with substrate corresponds to:
A. Vmax
B. Km
C. Half Vmax
D. Zero activity
Answer: A
60. Which is an example of an enzyme working outside the body?
A. Amylase in mouth
B. Pepsin in stomach
C. Papain in meat tenderiser
D. Trypsin in intestine
Answer: C
4. Vitamins (10 MCQs)
61. Which vitamin is also known as ascorbic acid?
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin E
Answer: B
62. Deficiency of vitamin D causes:
A. Scurvy
B. Rickets
C. Beriberi
D. Pellagra
Answer: B
63. Which vitamin is fat-soluble?
A. Vitamin B₁
B. Vitamin B₂
C. Vitamin C
D. Vitamin K
Answer: D
64. Night blindness is caused by deficiency of:
A. Vitamin A
B. Vitamin B₁₂
C. Vitamin C
D. Vitamin K
Answer: A
65. Pellagra is caused by deficiency of:
A. Niacin (B₃)
B. Thiamine (B₁)
C. Riboflavin (B₂)
D. Pantothenic acid (B₅)
Answer: A
66. Which vitamin acts as an antioxidant?
A. Vitamin A
B. Vitamin C
C. Vitamin E
D. All of these
Answer: D
67. Which vitamin is required for blood clotting?
A. Vitamin A
B. Vitamin D
C. Vitamin E
D. Vitamin K
Answer: D
68. Which vitamin can be synthesised in the skin by sunlight?
A. Vitamin A
B. Vitamin D
C. Vitamin E
D. Vitamin K
Answer: B
69. Which vitamin has cobalt in its structure?
A. Vitamin B₆
B. Vitamin B₁₂
C. Vitamin B₂
D. Vitamin C
Answer: B
70. (Diagram-based) The given structure corresponds to:
(Structure of retinol)
A. Vitamin A
B. Vitamin D
C. Vitamin E
D. Vitamin K
Answer: A
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5. Nucleic Acids (DNA & RNA) (20 MCQs)
71. Nucleic acids are polymers of:
A. Nucleotides
B. Amino acids
C. Monosaccharides
D. Fatty acids
Answer: A
72. The sugar present in DNA is:
A. Ribose
B. Deoxyribose
C. Glucose
D. Fructose
Answer: B
73. The sugar present in RNA is:
A. Ribose
B. Deoxyribose
C. Fructose
D. Glucose
Answer: A
74. Which nitrogen base is present in RNA but not in DNA?
A. Adenine
B. Thymine
C. Uracil
D. Cytosine
Answer: C
75. In DNA, complementary base pairing occurs between:
A. A–G and C–T
B. A–T and C–G
C. A–C and T–G
D. A–U and C–G
Answer: B
76. The bond between sugar and base in a nucleotide is:
A. Glycosidic bond
B. Peptide bond
C. Phosphodiester bond
D. Hydrogen bond
Answer: A
77. The bond between nucleotides in a polynucleotide chain is:
A. Peptide bond
B. Glycosidic bond
C. Phosphodiester bond
D. Disulphide bond
Answer: C
78. Chargaff’s rule states:
A. A = T and G = C
B. A = G and T = C
C. A + T = G + C
D. A/T = G/C
Answer: A
79. Which scientist proposed the double helix structure of DNA?
A. Watson and Crick
B. Meselson and Stahl
C. Avery and MacLeod
D. Hershey and Chase
Answer: A
80. DNA replication is:
A. Conservative
B. Semiconservative
C. Dispersive
D. None of these
Answer: B
81. Which type of RNA carries amino acids to ribosomes?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: B
82. Which type of RNA forms ribosomes?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: C
83. Which type of RNA carries genetic information from DNA to
ribosomes?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: A
84. Transcription is the process of:
A. Protein synthesis
B. DNA to RNA formation
C. RNA to DNA formation
D. DNA replication
Answer: B
85. Translation is the process of:
A. DNA to RNA
B. RNA to protein
C. RNA to DNA
D. DNA to protein
Answer: B
86. Which base pair is connected by three hydrogen bonds?
A. A–T
B. G–C
C. A–U
D. C–U
Answer: B
87. The total number of base pairs in human DNA is
approximately:
A. 3 million
B. 3 billion
C. 6 million
D. 6 billion
Answer: B
88. The length of DNA in a human cell is approximately:
A. 2.2 m
B. 2.2 cm
C. 22 cm
D. 22 m
Answer: A
89. (Diagram-based) The given diagram shows: (Double helix with
labelled strands)
A. DNA secondary structure
B. RNA structure
C. tRNA cloverleaf
D. Chromosome diagram
Answer: A
90. Which RNA acts as an adapter molecule during protein
synthesis?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: B
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6. Hormones & Miscellaneous Concepts (10 MCQs)
91. Hormones are:
A. Carbohydrates
B. Lipids
C. Chemical messengers
D. Proteins only
Answer: C
92. Which hormone regulates blood sugar level?
A. Thyroxine
B. Insulin
C. Adrenaline
D. Estrogen
Answer: B
93. Which hormone is a steroid?
A. Insulin
B. Cortisol
C. Glucagon
D. Oxytocin
Answer: B
94. Which hormone is secreted by adrenal medulla?
A. Cortisol
B. Adrenaline
C. Thyroxine
D. Insulin
Answer: B
95. Which hormone controls basal metabolic rate?
A. Insulin
B. Thyroxine
C. Growth hormone
D. Testosterone
Answer: B
96. Which hormone promotes milk secretion?
A. Estrogen
B. Prolactin
C. Progesterone
D. Oxytocin
Answer: B
97. Which hormone is known as the fight-or-flight hormone?
A. Cortisol
B. Adrenaline
C. Insulin
D. Thyroxine
Answer: B
98. Which hormone stimulates protein synthesis?
A. Thyroxine
B. Testosterone
C. Glucagon
D. Melatonin
Answer: B
99. Which hormone is used in the treatment of inflammation?
A. Cortisol
B. Insulin
C. Progesterone
D. Estrogen
Answer: A
100. (Diagram-based) The given diagram shows: (Structure of
insulin with A and B chains)
A. Growth hormone
B. Insulin
C. Glucagon
D. Oxytocin
Answer: B

----- Board level MCQs ------

GSEB HSC Board – Biomolecules MCQ Practice (50 Questions)
1. Which of the following is a reducing sugar?
A. Sucrose
B. Maltose
C. Lactose
D. Both B and C
Answer: D
2. The formula of glucose is:
A. C₆H₁₂O₆
B. C₆H₁₀O₅
C. C₅H₁₀O₅
D. C₆H₁₂O₅
Answer: A
3. Invert sugar is a mixture of:
A. Glucose + Galactose
B. Glucose + Fructose
C. Glucose + Sucrose
D. Fructose + Maltose
Answer: B
4. The linkage present in starch is:
A. α-1,4 and α-1,6
B. β-1,4 and β-1,6
C. α-1,4 only
D. β-1,4 only
Answer: A
5. Which polysaccharide is the main storage carbohydrate in
plants?
A. Glycogen
B. Cellulose
C. Starch
D. Inulin
Answer: C
6. The main structural polysaccharide in plants is:
A. Cellulose
B. Chitin
C. Amylose
D. Glycogen
Answer: A
7. Which sugar is present in DNA?
A. Ribose
B. Deoxyribose
C. Glucose
D. Fructose
Answer: B
8. Which sugar is present in RNA?
A. Deoxyribose
B. Ribose
C. Fructose
D. Mannose
Answer: B
9. The bond between two amino acids is:
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Disulphide bond
Answer: B
10. Which is the simplest amino acid?
A. Alanine
B. Glycine
C. Serine
D. Valine
Answer: B
11. Which amino acid contains sulphur?
A. Alanine
B. Glycine
C. Cysteine
D. Proline
Answer: C
12. The test used to detect proteins by violet colour is:
A. Biuret test
B. Ninhydrin test
C. Xanthoproteic test
D. Millon’s test
Answer: A
13. Enzymes are chemically:
A. Lipids
B. Carbohydrates
C. Proteins
D. Vitamins
Answer: C
14. Which enzyme converts starch to maltose?
A. Amylase
B. Maltase
C. Invertase
D. Zymase
Answer: A
15. Which vitamin is ascorbic acid?
A. Vitamin A
B. Vitamin B₁
C. Vitamin C
D. Vitamin D
Answer: C
16. Deficiency of vitamin D causes:
A. Scurvy
B. Rickets
C. Beriberi
D. Pellagra
Answer: B
17. Deficiency of vitamin A causes:
A. Night blindness
B. Scurvy
C. Rickets
D. Pellagra
Answer: A
18. Pellagra is caused by deficiency of:
A. Niacin
B. Thiamine
C. Riboflavin
D. Pantothenic acid
Answer: A
19. Which vitamin is required for blood clotting?
A. Vitamin A
B. Vitamin D
C. Vitamin E
D. Vitamin K
Answer: D
20. The nitrogen base present in RNA but absent in DNA is:
A. Thymine
B. Uracil
C. Cytosine
D. Adenine
Answer: B
21. The nitrogen base present in DNA but absent in RNA is:
A. Thymine
B. Uracil
C. Cytosine
D. Adenine
Answer: A
22. Complementary base pairing in DNA is:
A. A–T and G–C
B. A–G and T–C
C. A–U and G–C
D. A–C and T–G
Answer: A
23. Number of hydrogen bonds between G and C in DNA is:
A. 2
B. 3
C. 4
D. 1
Answer: B
24. The sugar and base are linked by:
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Phosphodiester bond
Answer: A
25. Nucleotides are linked by:
A. Glycosidic bonds
B. Peptide bonds
C. Phosphodiester bonds
D. Hydrogen bonds
Answer: C
26. DNA replication is:
A. Conservative
B. Semiconservative
C. Dispersive
D. None of these
Answer: B
27. Which RNA carries amino acids to ribosome?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: B
28. Which RNA carries the genetic code?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: A
29. Which RNA forms ribosomes?
A. mRNA
B. tRNA
C. rRNA
D. snRNA
Answer: C
30. Translation is:
A. DNA → RNA
B. RNA → Protein
C. DNA → DNA
D. RNA → DNA
Answer: B
31. Which hormone regulates blood sugar level?
A. Insulin
B. Thyroxine
C. Adrenaline
D. Estrogen
Answer: A
32. Which hormone is known as fight-or-flight hormone?
A. Cortisol
B. Adrenaline
C. Thyroxine
D. Progesterone
Answer: B
33. Hormones are:
A. Enzymes
B. Vitamins
C. Chemical messengers
D. Nucleic acids
Answer: C
34. Collagen is a:
A. Fibrous protein
B. Globular protein
C. Conjugated protein
D. Hormone
Answer: A
35. Hemoglobin is a:
A. Fibrous protein
B. Globular protein
C. Hormone
D. Lipoprotein
Answer: B
36. The monomer units of proteins are:
A. Fatty acids
B. Amino acids
C. Monosaccharides
D. Nucleotides
Answer: B
37. The number of amino acids in nature is:
A. 10
B. 20
C. 30
D. 40
Answer: B
38. The number of peptide bonds in a tripeptide is:
A. 1
B. 2
C. 3
D. 4
Answer: B
39. Which of the following is a fibrous protein?
A. Myosin
B. Hemoglobin
C. Albumin
D. Pepsin
Answer: A
40. The enzyme that hydrolyses urea is:
A. Urease
B. Amylase
C. Maltase
D. Lactase
Answer: A
41. The optimum temperature for most human enzymes is:
A. 25°C
B. 37°C
C. 45°C
D. 50°C
Answer: B
42. The sugar in ATP is:
A. Ribose
B. Deoxyribose
C. Glucose
D. Fructose
Answer: A
43. Starch on complete hydrolysis gives:
A. Glucose
B. Fructose
C. Maltose
D. Galactose
Answer: A
44. Which sugar is found in milk?
A. Glucose
B. Lactose
C. Maltose
D. Sucrose
Answer: B
45. Which sugar is called fruit sugar?
A. Glucose
B. Fructose
C. Maltose
D. Lactose
Answer: B
46. Which sugar is the sweetest?
A. Glucose
B. Fructose
C. Maltose
D. Sucrose
Answer: B
47. The sugar present in honey is:
A. Fructose and Glucose
B. Glucose and Galactose
C. Sucrose and Fructose
D. Lactose and Glucose
Answer: A
48. Cellulose is made up of:
A. α-glucose
B. β-glucose
C. Ribose
D. Fructose
Answer: B
49. Amylose is a component of:
A. Glycogen
B. Starch
C. Cellulose
D. Inulin
Answer: B
50. In DNA, the two strands are held together by:
A. Covalent bonds
B. Ionic bonds
C. Hydrogen bonds
D. Peptide bonds
Answer: C

------------------------------------------

Biomolecules (50 GSEB Board Style MCQs)

1. Carbohydrates
1. Which of the following is a reducing sugar?
A. Sucrose
B. Glucose
C. Starch
D. Cellulose
2. The basic unit of cellulose is:
A. α-D-glucose
B. β-D-glucose
C. α-D-fructose
D. β-D-fructose
3. Maltose is composed of:
A. Glucose + Galactose
B. Glucose + Fructose
C. Glucose + Glucose
D. Galactose + Galactose
4. Which test is used to detect the presence of reducing sugars?
A. Biuret test
B. Fehling’s test
C. Ninhydrin test
D. Molisch’s test
5. Which of the following is a polysaccharide?
A. Glucose
B. Maltose
C. Lactose
D. Starch
---
2. Proteins & Amino Acids
6. The monomeric units of proteins are:
A. Monosaccharides
B. Amino acids
C. Fatty acids
D. Nucleotides
7. The isoelectric point of an amino acid is the pH at which:
A. It carries only a positive charge
B. It carries only a negative charge
C. Net charge is zero
D. It is insoluble in water
8. Which bond links amino acids in proteins?
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Phosphodiester bond
9. Primary structure of protein refers to:
A. Sequence of amino acids
B. Alpha-helix arrangement
C. Beta-pleated sheet
D. 3D folding of chains
10. The test for detection of proteins is:
A. Benedict’s test
B. Biuret test
C. Molisch’s test
D. Tollen’s test
---
3. Enzymes
11. Enzymes are chemically:
A. Carbohydrates
B. Proteins
C. Lipids
D. Nucleic acids
12. The non-protein part of an enzyme is called:
A. Apoenzyme
B. Holoenzyme
C. Cofactor
D. Substrate
13. The vitamin niacin is a part of coenzyme:
A. FAD
B. NAD⁺
C. TPP
D. CoA
14. The unit of enzyme activity is often expressed as:
A. Katal
B. Volt
C. Joule
D. Newton
15. Which factor does NOT affect enzyme activity?
A. pH
B. Temperature
C. Light intensity
D. Substrate concentration
---
4. Vitamins
16. Deficiency of vitamin C causes:
A. Night blindness
B. Scurvy
C. Rickets
D. Beriberi
17. Vitamin D is:
A. Water soluble
B. Fat soluble
C. Insoluble in lipids
D. Insoluble in fats
18. The chemical name of vitamin B₁ is:
A. Thiamine
B. Riboflavin
C. Niacin
D. Pyridoxine
19. Vitamin K is essential for:
A. Vision
B. Blood clotting
C. Growth
D. Calcium absorption
20. Which of the following vitamins is heat labile?
A. Vitamin C
B. Vitamin D
C. Vitamin A
D. Vitamin K
---
5. Nucleic Acids
21. DNA contains:
A. Adenine, Guanine, Uracil, Cytosine
B. Adenine, Guanine, Cytosine, Thymine
C. Adenine, Cytosine, Uracil, Thymine
D. Guanine, Cytosine, Uracil, Thymine
22. The sugar in RNA is:
A. Glucose
B. Deoxyribose
C. Ribose
D. Fructose
23. The base pairing in DNA is:
A. A–C, G–T
B. A–T, G–C
C. A–G, T–C
D. A–U, G–C
24. The bond between sugar and base in a nucleotide is:
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Disulfide bond
25. Which of the following is NOT a purine base?
A. Adenine
B. Guanine
C. Cytosine
D. None of these
---
6. Hormones
26. Which of the following is a peptide hormone?
A. Insulin
B. Thyroxine
C. Cortisone
D. Testosterone
27. Thyroxine contains which element?
A. Sodium
B. Potassium
C. Iodine
D. Calcium
28. Adrenaline is secreted by:
A. Thyroid gland
B. Pituitary gland
C. Adrenal medulla
D. Pancreas
29. Which hormone regulates blood sugar level?
A. Thyroxine
B. Insulin
C. Testosterone
D. Cortisone
30. Which hormone is steroid in nature?
A. Insulin
B. Estrogen
C. Glucagon
D. Oxytocin
---
7. Lipids
31. Which of the following is NOT a lipid?
A. Cholesterol
B. Triglyceride
C. Lecithin
D. Glycogen
32. The simplest lipid is:
A. Wax
B. Fat
C. Oil
D. Steroid
33. Which fatty acid is essential for humans?
A. Palmitic acid
B. Linoleic acid
C. Stearic acid
D. Oleic acid
34. The bond in triglycerides is:
A. Peptide bond
B. Glycosidic bond
C. Ester bond
D. Hydrogen bond
35. Which lipid forms cell membrane structure?
A. Cholesterol
B. Phospholipids
C. Steroids
D. Glycolipids
---
8. Miscellaneous & Applications
36. Benedict’s solution is used to test for:
A. Lipids
B. Proteins
C. Reducing sugars
D. Amino acids
37. The carbohydrate that is the main source of energy in humans
is:
A. Glucose
B. Sucrose
C. Fructose
D. Lactose
38. Which of the following is an example of disaccharide?
A. Starch
B. Cellulose
C. Sucrose
D. Glucose
39. The term “invert sugar” refers to:
A. Glucose + Galactose
B. Glucose + Fructose
C. Galactose + Fructose
D. Fructose + Sucrose
40. The structural polysaccharide in arthropods is:
A. Cellulose
B. Glycogen
C. Chitin
D. Starch
---
9. Higher NCERT Lines
41. The base present in ATP but absent in DNA is:
A. Adenine
B. Guanine
C. Uracil
D. Cytosine
42. The vitamin that functions as an antioxidant is:
A. Vitamin C
B. Vitamin D
C. Vitamin B₁
D. Vitamin K
43. Which of the following is a non-reducing sugar?
A. Glucose
B. Maltose
C. Lactose
D. Sucrose
44. The coenzyme derived from vitamin B₂ is:
A. FAD
B. NAD⁺
C. CoA
D. TPP
45. The enzyme that hydrolyses starch into maltose is:
A. Maltase
B. Amylase
C. Lactase
D. Sucrase
---
10. Diagram & Structure Based
46. In the Fischer projection, the –OH group on the right of the last
chiral carbon in glucose indicates:
A. D-configuration
B. L-configuration
C. α-anomer
D. β-anomer
47. Identify the α-helix as part of:
A. Primary protein structure
B. Secondary protein structure
C. Tertiary protein structure
D. Quaternary protein structure
48. Which diagram represents β-D-glucose?
A. Chair form with OH on C₁ down
B. Chair form with OH on C₁ up
C. Fischer projection
D. Open chain aldehyde
49. The double helical structure of DNA was proposed by:
A. Watson and Crick
B. Avery and MacLeod
C. Franklin and Chargaff
D. Hershey and Chase
50. The diagram of nucleotide shows phosphate attached to:
A. Sugar’s C-2'
B. Sugar’s C-3'
C. Sugar’s C-5'
D. Sugar’s C-1'