NEETAceToday's NEET Daily

General introduction and importance: NEET MCQs with answers

50 questions on this topic of Biomolecules (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

Practise Biomolecules freeAll Biomolecules questions

Free with a Google sign-in; NEET Daily needs no sign-in at all.

easy

1. Which of the following statements is INCORRECT regarding the general importance and occurrence of biomolecules in living systems?

  1. Nucleic acids are responsible for direct mechanical support of cell membranes
  2. Carbohydrates are utilized as immediate energy reserves in the form of glycogen and starch
  3. Phospholipids are vital structural components of cellular membranes
  4. Enzymes are highly specific in their action and operate under mild physiological conditions
Show answer and explanation

Answer: (A) Nucleic acids are responsible for direct mechanical support of cell membranes

Nucleic acids (DNA and RNA) are responsible for the storage, transmission, and translation of genetic information, not for mechanical support of membranes. Mechanical support is provided by proteins (cytoskeleton) and cell walls/extracellular matrix.

medium

2. Proteins are polymers of:

  1. Glucose units
  2. Nucleotides
  3. Fatty acids and glycerol
  4. α-Amino acids joined by peptide bonds
Show answer and explanation

Answer: (D) α-Amino acids joined by peptide bonds

Proteins are long polymers of α-amino acids linked by peptide (amide) bonds, forming the structural and functional basis of life.

NCERT Class 12

hard

3. Assertion (A): The maintenance of a living organism requires a continuous input of energy and a non-equilibrium steady state. Reason (R): Living systems are at thermodynamic equilibrium, which maximizes metabolic efficiency.

  1. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
  2. Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  3. Assertion (A) is true, but Reason (R) is false.
  4. Assertion (A) is false, but Reason (R) is true.
Show answer and explanation

Answer: (C) Assertion (A) is true, but Reason (R) is false.

The living state is a non-equilibrium, steady state that allows work to be performed continuously. Systems at equilibrium cannot perform work; therefore, a living organism constantly works to avoid reaching thermodynamic equilibrium.

medium

4. Consider the following statements regarding the biological importance of biomolecules: Statement I: Living systems are composed of non-living atoms and molecules that interact to sustain life processes. Statement II: Nucleic acids are exclusively responsible for catalyzing metabolic transformations in cells. Choose the correct option:

  1. Statement I is correct, but Statement II is incorrect.
  2. Both Statement I and Statement II are correct.
  3. Statement I is incorrect, but Statement II is correct.
  4. Both Statement I and Statement II are incorrect.
Show answer and explanation

Answer: (A) Statement I is correct, but Statement II is incorrect.

Living systems are made of lifeless atoms and molecules that function together to sustain the living state, making Statement I correct. Statement II is incorrect because proteins (enzymes) are the primary biocatalysts for metabolic processes, though certain RNA molecules (ribozymes) also exhibit catalytic properties.

easy

5. A sample of dry plant tissue is completely incinerated to carbon dioxide and water. The remaining ash consists predominantly of:

  1. Unburnt microcrystalline cellulose fibers
  2. Water-soluble vitamins and nucleotides
  3. Residual denatured structural proteins
  4. Inorganic elements like calcium, magnesium, and potassium
Show answer and explanation

Answer: (D) Inorganic elements like calcium, magnesium, and potassium

When a tissue is fully burnt, all organic compounds (carbohydrates, proteins, nucleic acids, lipids) are oxidized into gaseous forms (CO₂, H₂O) and escape. The remaining residue, known as ash, contains inorganic elemental salts like Ca²⁺, Mg²⁺, K⁺, and phosphates.

hard

6. The dynamic nature of living organisms involves continuous chemical conversions called metabolism. In this context, which of the following statements is chemically accurate?

  1. Metabolic pathways are always completely isolated, linear, and never interconnected
  2. Catabolism refers exclusively to energy-consuming biosynthetic reactions
  3. Anabolism releases energy by breaking down macromolecules into carbon dioxide and water
  4. Metabolic transformations are catalyzed reactions, and there is no uncatalyzed metabolic conversion in living systems
Show answer and explanation

Answer: (D) Metabolic transformations are catalyzed reactions, and there is no uncatalyzed metabolic conversion in living systems

In living systems, every chemical reaction is catalyzed by specific biocatalysts (enzymes), and even simple dissolutions such as CO₂ hydration are catalyzed in vivo. Anabolism is biosynthetic (consumes energy), while catabolism is degradative (releases energy).

medium

7. Biomolecules perform specialized physiological roles in multicellular organisms. Which of the following compounds is a proteinaceous oxygen-transport pigment found in vertebrate blood?

  1. Keratin
  2. Chlorophyll
  3. Myoglobin
  4. Hemoglobin
Show answer and explanation

Answer: (D) Hemoglobin

Hemoglobin is a conjugated protein containing an iron-porphyrin complex that functions as the primary oxygen carrier in the blood of vertebrates. Chlorophyll is a magnesium-containing pigment in plants, myoglobin functions primarily for oxygen storage in muscle tissue, and keratin is a structural fibrous protein.

medium

8. Match List-I (Biomolecule / Structure) with List-II (Distinct Chemical Characteristic): List-I: (A) DNA (B) Cellulose (C) Phospholipid (D) Protein List-II: (I) Amphipathic nature with hydrophobic tail and polar head (II) Unbranched polymer of β-D-glucose units (III) Antiparallel double-helical polydeoxyribonucleotide (IV) Polyamide chain exhibiting specific chiral α-amino acids

  1. (A)-(III), (B)-(I), (C)-(II), (D)-(IV)
  2. (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
  3. (A)-(III), (B)-(II), (C)-(I), (D)-(IV)
  4. (A)-(IV), (B)-(II), (C)-(I), (D)-(III)
Show answer and explanation

Answer: (C) (A)-(III), (B)-(II), (C)-(I), (D)-(IV)

DNA is an antiparallel double helix of deoxyribonucleotides. Cellulose is an unbranched structural polysaccharide composed of β-D-glucose residues. Phospholipids contain both hydrophilic heads and hydrophobic tails (amphipathic). Proteins are polyamides formed from L-α-amino acids.

easy

9. Statement I: Hormones derived from proteins or steroids act as intercellular chemical messengers in living organisms. Statement II: Vitamins are organic compounds required in large quantities in human diet because the body can synthesize all of them abundantly. In the light of the above statements, choose the correct option:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
Show answer and explanation

Answer: (B) Statement I is correct but Statement II is incorrect

Statement I is correct as hormones act as chemical messengers that help regulate physiological processes. Statement II is incorrect because vitamins are micro-nutrients required in minute amounts, and most vitamins cannot be synthesized by human body tissues.

easy

10. Given below are two statements: Statement I: Living organisms obtain energy required for life processes by the controlled chemical oxidation of complex organic biomolecules. Statement II: The ultimate chemical breakdown of glucose during cellular respiration to yield carbon dioxide, water, and energy is an exclusively non-enzymatic spontaneous reaction. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
Show answer and explanation

Answer: (B) Statement I is correct but Statement II is incorrect

Statement I is correct because living organisms extract energy through coordinated chemical oxidation of fuel molecules like carbohydrates and fats. Statement II is incorrect because cellular respiration comprises a series of tightly regulated, enzyme-catalyzed metabolic steps, rather than a spontaneous non-enzymatic reaction.

hard

11. A biochemist determines the empirical formula of an unbranched energy-storage biomolecule to be (CH₂O)ₙ with a molar mass of approximately 1.8 × 10⁵ g mol⁻¹. How many hexose monomer units (C₆H₁₂O₆, molar mass = 180 g mol⁻¹) were condensed to form this polysaccharide chain? (Consider loss of one H₂O per glycosidic bond formed; formula of anhydro-hexose unit = C₆H₁₀O₅, molar mass = 162 g mol⁻¹)

  1. 100
  2. 555
  3. 1800
  4. 1111
Show answer and explanation

Answer: (D) 1111

Condensation of n hexose units produces a polysaccharide of formula (C₆H₁₀O₅)ₙ·H₂O. Neglecting terminal water for high molecular weight, molecular mass ≈ n × 162 g mol⁻¹. Thus, n = (1.8 × 10⁵) / 162 ≈ 1111 monomer units.

easy

12. Which of the following pairs of cellular polymers and their characteristic repeating inter-monomeric linkage is correctly matched?

  1. Polysaccharides : Phosphodiester linkage
  2. Nucleic acids : Glycosidic linkage
  3. Polypeptides : Peptide (amide) linkage
  4. Triglycerides : Disulfide linkage
Show answer and explanation

Answer: (C) Polypeptides : Peptide (amide) linkage

Polypeptides (proteins) are formed by joining amino acid residues via peptide (-CO-NH-) bonds. Polysaccharides feature glycosidic linkages, and nucleic acids feature phosphodiester linkages. Triglycerides are esters, not true repeating polymers.

Keep going with Biomolecules. All 375 questions with instant answers, your mistakes saved for revision and your accuracy by topic.
Start practising

Other topics in Biomolecules