Biomolecules – Daily Practice Problem (DPP)

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🎯 NEET 2026 Daily Practice Problem (DPP)

Topic: Biomolecules | 20 High-Yield MCQs

Q1. Which of the following is the most abundant protein in the whole of the biosphere?

  1. Collagen
  2. RuBisCO
  3. Insulin
  4. Trypsin
✅ View Answer & Explanation

Correct Answer: (2) RuBisCO
Explanation: RuBisCO is the most abundant protein in the biosphere. Collagen is the most abundant protein in the animal world.

Q2. Amino acids are substituted methanes. The four substituent groups occupying the four valency positions of the alpha-carbon are:

  1. Hydrogen, carboxyl group, amino group, and a variable R group
  2. Hydrogen, hydroxyl group, amino group, and R group
  3. Hydrogen, carboxyl group, nitro group, and R group
  4. Nitrogen, carboxyl group, amino group, and R group
✅ View Answer & Explanation

Correct Answer: (1) Hydrogen, carboxyl group, amino group, and a variable R group
Explanation: This general structure is common to all alpha-amino acids; they differ only in the nature of the R group.

Q3. Which of the following is a non-reducing sugar?

  1. Glucose
  2. Sucrose
  3. Lactose
  4. Maltose
✅ View Answer & Explanation

Correct Answer: (2) Sucrose
Explanation: Sucrose is a non-reducing sugar because its aldehyde and ketone groups are involved in the glycosidic bond formation.

Q4. Lecithin is an example of:

  1. Simple lipid
  2. Derived lipid
  3. Phospholipid
  4. Neutral fat
✅ View Answer & Explanation

Correct Answer: (3) Phospholipid
Explanation: Lecithin is a phosphorus-containing lipid commonly found in cell membranes.

Q5. The bond found between two nucleotides in a nucleic acid is:

  1. Glycosidic bond
  2. Peptide bond
  3. 3′-5′ phosphodiester bond
  4. Hydrogen bond
✅ View Answer & Explanation

Correct Answer: (3) 3′-5′ phosphodiester bond
Explanation: Nucleotides are linked together by phosphodiester bonds to form a polynucleotide chain.

Q6. ‘Primary Metabolites’ have identifiable functions in host ecology, while ‘Secondary Metabolites’ like alkaloids and rubber are:

  1. Always harmful to humans
  2. Essential for primary growth
  3. Not directly involved in normal growth and development
  4. Found only in animals
✅ View Answer & Explanation

Correct Answer: (3) Not directly involved in normal growth and development
Explanation: Secondary metabolites are mostly produced by plants, fungi, and microbes and often have ecological importance (defense) or human use.

Q7. Chitin is a polymer of:

  1. Glucose
  2. N-acetyl glucosamine
  3. Fructose
  4. Glycerol
✅ View Answer & Explanation

Correct Answer: (2) N-acetyl glucosamine
Explanation: Chitin is a complex homopolysaccharide found in the exoskeleton of arthropods and fungal cell walls.

Q8. The pitch of B-DNA is:

  1. 3.4 nm
  2. 0.34 nm
  3. 2 nm
  4. 20 nm
✅ View Answer & Explanation

Correct Answer: (1) 3.4 nm
Explanation: The pitch (one full turn) of the DNA helix is 3.4 nm, containing 10 base pairs.

Q9. Enzymes work by:

  1. Increasing the activation energy
  2. Lowering the activation energy
  3. Increasing the temperature
  4. Changing the pH
✅ View Answer & Explanation

Correct Answer: (2) Lowering the activation energy
Explanation: By lowering the activation energy barrier, enzymes increase the rate of biochemical reactions.

Q10. Competitive inhibition of an enzyme occurs when:

  1. The inhibitor binds to the allosteric site
  2. The inhibitor closely resembles the substrate in its molecular structure
  3. The substrate concentration is very low
  4. The enzyme is denatured
✅ View Answer & Explanation

Correct Answer: (2) The inhibitor closely resembles the substrate
Explanation: Due to structural similarity, the inhibitor competes with the substrate for the active site (e.g., inhibition of succinic dehydrogenase by malonate).

Q11. A prosthetic group is a co-factor that is:

  1. Loosely attached to the apoenzyme
  2. A protein part of the enzyme
  3. Tightly bound to the apoenzyme
  4. Always a metal ion
✅ View Answer & Explanation

Correct Answer: (3) Tightly bound to the apoenzyme
Explanation: Prosthetic groups are organic compounds distinguished from other co-factors by being tightly bound (e.g., Haem in peroxidase).

Q12. The most abundant organic constituent of a living cell is:

  1. Water
  2. Proteins
  3. Carbohydrates
  4. Lipids
✅ View Answer & Explanation

Correct Answer: (2) Proteins
Explanation: Water is the most abundant constituent (70-90%), but among organic compounds, proteins are the most abundant (10-15%).

Q13. Inulin is a polymer of:

  1. Glucose
  2. Fructose
  3. Galactose
  4. Mannose
✅ View Answer & Explanation

Correct Answer: (2) Fructose
Explanation: Inulin is a storage polysaccharide found in some plants (like Dahlia tubers) and is a polymer of fructose.

Q14. An example of an acidic amino acid is:

  1. Lysine
  2. Valine
  3. Glutamic acid
  4. Tyrosine
✅ View Answer & Explanation

Correct Answer: (3) Glutamic acid
Explanation: Glutamic acid and Aspartic acid are acidic amino acids. Lysine is basic; Valine is neutral.

Q15. The ‘lock and key’ hypothesis of enzyme action was proposed by:

  1. Emil Fischer
  2. Koshland
  3. Watson
  4. Kuhne
✅ View Answer & Explanation

Correct Answer: (1) Emil Fischer
Explanation: Emil Fischer proposed the lock and key model, whereas Koshland proposed the ‘Induced fit’ model.

Q16. Zwitterionic form of an amino acid exists at:

  1. Very low pH
  2. Very high pH
  3. Isoelectric point
  4. Boiling point
✅ View Answer & Explanation

Correct Answer: (3) Isoelectric point
Explanation: At a specific pH called the isoelectric point, the amino acid carries both positive and negative charges, making it electrically neutral.

Q17. Which of the following is not a macromolecule?

  1. Polysaccharides
  2. Proteins
  3. Nucleic acids
  4. Lipids
✅ View Answer & Explanation

Correct Answer: (4) Lipids
Explanation: Strictly speaking, lipids are not macromolecules because their molecular weight does not exceed 800 Da. They appear in the acid-insoluble fraction because they form vesicles (aggregates).

Q18. Primary structure of a protein refers to:

  1. The 3D folding of the chain
  2. The sequence of amino acids
  3. The alpha-helix structure
  4. The assembly of multiple subunits
✅ View Answer & Explanation

Correct Answer: (2) The sequence of amino acids
Explanation: Primary structure is the positional information of amino acids (which is first, which is second, etc.).

Q19. Which of the following nitrogenous bases is found only in RNA?

  1. Adenine
  2. Guanine
  3. Cytosine
  4. Uracil
✅ View Answer & Explanation

Correct Answer: (4) Uracil
Explanation: DNA contains A, G, C, and Thymine. RNA contains A, G, C, and Uracil.

Q20. In a DNA molecule, the steps of the ladder are formed by:

  1. Sugar and phosphate
  2. Nitrogenous bases
  3. Phosphate only
  4. Sugar only
✅ View Answer & Explanation

Correct Answer: (2) Nitrogenous bases
Explanation: The sugar-phosphate backbone forms the railings, while the base pairs form the steps of the DNA ladder.

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