MCQs on Biomolecules – CBSE Class 11 Biology
MCQs on Biomolecules – CBSE Class 11 Biology (Unit III | NCERT-Based)
CBSE Class 11 Biology – MCQs with Answers and Explanations
Unit III: Cell Structure and Function
Topic: Biomolecules
Section A: Introduction to Biomolecules & Chemical Analysis (Q1–Q10)
Q1. Biomolecules are defined as:
A. Inorganic compounds found in cells
B. Organic compounds present in living organisms
C. Minerals dissolved in cytoplasm
D. Waste products of metabolism
Answer: B
Explanation: Biomolecules are organic compounds like carbohydrates, proteins, lipids, and nucleic acids that form the structural and functional basis of living organisms.
Q2. Which of the following is NOT a biomolecule?
A. Protein
B. Lipid
C. Water
D. Nucleic acid
Answer: C
Explanation: Water is an inorganic molecule, whereas proteins, lipids, and nucleic acids are organic biomolecules.
Q3. The four major classes of biomolecules are:
A. Proteins, lipids, carbohydrates, minerals
B. Carbohydrates, proteins, lipids, nucleic acids
C. Vitamins, enzymes, hormones, water
D. Sugars, fats, salts, gases
Answer: B
Explanation: NCERT classifies biomolecules into carbohydrates, proteins, lipids, and nucleic acids.
Q4. The molecular weight of biomolecules is generally:
A. Very low
B. Less than water
C. High
D. Zero
Answer: C
Explanation: Biomolecules are usually high molecular weight compounds.
Q5. Macromolecules are those with molecular weight:
A. Below 1000
B. Between 1000–2000
C. Above 1000
D. Equal to water
Answer: C
Explanation: Macromolecules have a molecular weight greater than 1000 daltons.
Q6. Which technique is used to separate biomolecules?
A. Distillation
B. Chromatography
C. Filtration
D. Sedimentation
Answer: B
Explanation: Chromatography separates biomolecules based on size, charge, or affinity.
Q7. Acid-soluble pool contains:
A. Proteins and lipids
B. Macromolecules only
C. Micromolecules
D. Cell organelles
Answer: C
Explanation: Acid-soluble pool contains micromolecules like amino acids and sugars.
Q8. Acid-insoluble pool consists mainly of:
A. Vitamins
B. Ions
C. Macromolecules
D. Water
Answer: C
Explanation: Acid-insoluble fraction includes proteins, nucleic acids, lipids, and polysaccharides.
Q9. Which element is most abundant in biomolecules?
A. Nitrogen
B. Oxygen
C. Carbon
D. Hydrogen
Answer: C
Explanation: Carbon forms the backbone of all organic biomolecules.
Q10. The term “biomolecule” excludes:
A. Enzymes
B. Hormones
C. Water
D. DNA
Answer: C
Explanation: Water is inorganic and not considered a biomolecule.
Section B: Carbohydrates (Q11–Q20)
Q11. Carbohydrates are chemically:
A. Aldehydes or ketones
B. Alcohols only
C. Acids only
D. Proteins
Answer: A
Explanation: Carbohydrates are polyhydroxy aldehydes or ketones.
Q12. Which is the simplest form of carbohydrate?
A. Disaccharide
B. Polysaccharide
C. Monosaccharide
D. Oligosaccharide
Answer: C
Explanation: Monosaccharides are the simplest carbohydrates.
Q13. Glucose is an example of:
A. Pentose sugar
B. Hexose sugar
C. Disaccharide
D. Polysaccharide
Answer: B
Explanation: Glucose is a six-carbon (hexose) sugar.
Q14. The glycosidic bond is present in:
A. Proteins
B. Lipids
C. Carbohydrates
D. Nucleic acids
Answer: C
Explanation: Glycosidic bonds link monosaccharide units in carbohydrates.
Q15. Which carbohydrate is the main storage polysaccharide in plants?
A. Glycogen
B. Cellulose
C. Starch
D. Chitin
Answer: C
Explanation: Starch is the storage carbohydrate in plants.
Q16. Glycogen is stored in:
A. Plant cells
B. Animal liver and muscles
C. Fungal cell wall
D. Bacterial capsule
Answer: B
Explanation: Glycogen is the storage polysaccharide of animals.
Q17. Which polysaccharide provides structural support in plants?
A. Starch
B. Glycogen
C. Cellulose
D. Pectin
Answer: C
Explanation: Cellulose forms the plant cell wall.
Q18. Chitin is found in:
A. Plant cell wall
B. Animal tissues
C. Fungal cell wall
D. Bacterial membrane
Answer: C
Explanation: Chitin is a structural polysaccharide in fungi.
Q19. Sucrose is composed of:
A. Glucose + glucose
B. Glucose + fructose
C. Fructose + fructose
D. Galactose + glucose
Answer: B
Explanation: Sucrose is a disaccharide of glucose and fructose.
Q20. Which carbohydrate is non-reducing?
A. Glucose
B. Fructose
C. Lactose
D. Sucrose
Answer: D
Explanation: Sucrose is a non-reducing sugar.
Section C: Proteins & Amino Acids (Q21–Q35)
Q21. Proteins are polymers of:
A. Fatty acids
B. Nucleotides
C. Amino acids
D. Sugars
Answer: C
Explanation: Proteins are made of amino acids linked by peptide bonds.
Q22. The bond joining amino acids is called:
A. Glycosidic bond
B. Hydrogen bond
C. Peptide bond
D. Ester bond
Answer: C
Explanation: Peptide bonds form between –COOH and –NH₂ groups.
Q23. How many amino acids are commonly found in proteins?
A. 10
B. 15
C. 20
D. 25
Answer: C
Explanation: Proteins are made from 20 standard amino acids.
Q24. The general structure of an amino acid includes:
A. Only amino group
B. Only carboxyl group
C. Amino group, carboxyl group, R group
D. Phosphate group
Answer: C
Explanation: Each amino acid has –NH₂, –COOH, H, and R group.
Q25. Proteins that help in catalysis are called:
A. Hormones
B. Enzymes
C. Antibodies
D. Structural proteins
Answer: B
Explanation: Enzymes are biological catalysts.
Q26. Primary structure of protein refers to:
A. Coiled structure
B. Folding pattern
C. Amino acid sequence
D. Functional shape
Answer: C
Explanation: Primary structure is the linear sequence of amino acids.
Q27. Secondary structure of protein includes:
A. Peptide bonds
B. α-helix and β-pleated sheet
C. Tertiary folding
D. Quaternary association
Answer: B
Explanation: Secondary structure arises due to hydrogen bonding.
Q28. Which protein is fibrous?
A. Insulin
B. Haemoglobin
C. Keratin
D. Enzyme
Answer: C
Explanation: Keratin is a fibrous structural protein.
Q29. Globular proteins are generally:
A. Insoluble
B. Structural
C. Soluble and functional
D. Inert
Answer: C
Explanation: Globular proteins are functional and soluble.
Q30. Denaturation of proteins leads to loss of:
A. Primary structure
B. Secondary and tertiary structure
C. Amino acids
D. Peptide bonds
Answer: B
Explanation: Denaturation disrupts secondary and tertiary structures.
Q31. Which factor does NOT cause protein denaturation?
A. High temperature
B. Extreme pH
C. Heavy metals
D. Low molecular weight
Answer: D
Explanation: Temperature, pH, and metals cause denaturation; molecular weight does not.
Q32. Antibodies are examples of:
A. Structural proteins
B. Transport proteins
C. Defensive proteins
D. Contractile proteins
Answer: C
Explanation: Antibodies protect the body against pathogens.
Q33. Haemoglobin is a:
A. Enzyme
B. Hormone
C. Transport protein
D. Storage protein
Answer: C
Explanation: Haemoglobin transports oxygen in blood.
Q34. Which level of protein structure is lost first during denaturation?
A. Primary
B. Secondary
C. Amino acid level
D. Peptide level
Answer: B
Explanation: Secondary structure is affected before primary structure.
Q35. Enzymes are mostly made of:
A. Lipids
B. Carbohydrates
C. Proteins
D. Nucleic acids
Answer: C
Explanation: Most enzymes are proteinaceous.
Section D: Lipids, Nucleic Acids & Enzymes (Q36–Q50)
Q36. Lipids are:
A. Polymers
B. Insoluble in water
C. Water soluble
D. Charged molecules
Answer: B
Explanation: Lipids are hydrophobic and insoluble in water.
Q37. Which is NOT a lipid?
A. Fats
B. Oils
C. Waxes
D. Cellulose
Answer: D
Explanation: Cellulose is a polysaccharide, not a lipid.
Q38. Lipids are mainly composed of:
A. Fatty acids and glycerol
B. Amino acids
C. Nucleotides
D. Sugars
Answer: A
Explanation: Fats consist of fatty acids and glycerol.
Q39. Phospholipids are important components of:
A. Cell wall
B. Plasma membrane
C. Ribosome
D. Cell sap
Answer: B
Explanation: Phospholipids form the lipid bilayer of membranes.
Q40. DNA and RNA are polymers of:
A. Amino acids
B. Sugars
C. Nucleotides
D. Fatty acids
Answer: C
Explanation: Nucleic acids are polymers of nucleotides.
Q41. Which nitrogenous base is common in both DNA and RNA?
A. Thymine
B. Uracil
C. Cytosine
D. Adenine
Answer: D
Explanation: Adenine occurs in both DNA and RNA.
Q42. RNA differs from DNA in having:
A. Deoxyribose sugar
B. Thymine
C. Ribose sugar
D. Double helix
Answer: C
Explanation: RNA contains ribose sugar instead of deoxyribose.
Q43. Which bond links nucleotides together?
A. Peptide bond
B. Glycosidic bond
C. Phosphodiester bond
D. Hydrogen bond
Answer: C
Explanation: Nucleotides are joined by phosphodiester bonds.
Q44. Enzymes are specific because of their:
A. Size
B. Shape
C. Charge
D. Colour
Answer: B
Explanation: Enzyme specificity depends on active site shape.
Q45. The active site of an enzyme binds with:
A. Product
B. Substrate
C. Cofactor
D. Inhibitor
Answer: B
Explanation: Substrate binds to the active site.
Q46. Enzyme action model includes:
A. Lock and key only
B. Induced fit only
C. Both models
D. None
Answer: C
Explanation: NCERT explains lock-and-key and induced-fit models.
Q47. Which factor affects enzyme activity?
A. Temperature
B. pH
C. Substrate concentration
D. All of these
Answer: D
Explanation: Enzyme activity depends on multiple environmental factors.
Q48. Coenzymes are usually:
A. Proteins
B. Lipids
C. Organic molecules
D. Inorganic ions
Answer: C
Explanation: Coenzymes are organic non-protein molecules.
Q49. Enzyme inhibitors reduce activity by:
A. Increasing substrate
B. Blocking active site
C. Increasing temperature
D. Increasing pH
Answer: B
Explanation: Inhibitors prevent substrate binding.
Q50. Biomolecules are essential for:
A. Only structure
B. Only energy
C. Only heredity
D. All life processes
Answer: D
Explanation: Biomolecules support structure, metabolism, energy, and heredity.