Biomolecules NEET PYQs (2005–2026) with Solutions

10 solved Biomolecules PYQs

Real NEET and AIPMT questions from this chapter, newest first. Try each one, then open the answer and the step-by-step explanation.

1. Question 1 (NEET 2026)

   NEET 2026EasyStructure of proteins

   The correct statement about peptides and proteins is

   1. AOption A: Tertiary structure of proteins has two or more polypeptide subunits
   2. BOption B: Only the proteins having a quaternary structure are biologically active
   3. COption C: In $\beta$-pleated sheet structures, peptide chains are held together by intermolecular hydrogen bonds
   4. DOption D: In $\alpha$-helices, the polypeptide chain is twisted into a left-handed screw (helix) through intramolecular hydrogen bonds

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   Correct answer: (C) In $\beta$-pleated sheet structures, peptide chains are held together by intermolecular hydrogen bonds

   Explanation

   Option (A) is wrong. The tertiary structure is the overall folding of a single polypeptide chain. An arrangement of two or more polypeptide subunits is the quaternary structure. Option (B) is wrong. Many proteins made of a single folded chain (tertiary structure only) are fully biologically active; a quaternary structure is not required. Option (C) is correct. In the $\beta$-pleated sheet, the peptide chains lie side by side and are held together by intermolecular hydrogen bonds between $\mathrm{C{=}O}$ and $\mathrm{N{-}H}$ groups of neighbouring chains. Option (D) is wrong. In the $\alpha$-helix the chain is twisted into a right-handed screw, held by intramolecular hydrogen bonds between the $\mathrm{-NH}$ group of each amino acid residue and the $\mathrm{C{=}O}$ of an adjacent turn.

2. Question 2 (NEET 2026)

   NEET 2026EasyVitamins and their sources

   Match the vitamins in List I with their sources in List II List I: A. vitamin A B. vitamin $\mathrm{B_{12}}$ C. vitamin E D. vitamin K List II: I. meat II. sunflower oil III. green leafy vegetables IV. carrots Choose the correct answer from the options given below.

   1. AOption A: A-II, B-III, C-IV, D-I
   2. BOption B: A-IV, B-I, C-II, D-III
   3. COption C: A-IV, B-II, C-I, D-III
   4. DOption D: A-III, B-I, C-IV, D-II

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

   Explanation

   From the NCERT table of vitamins and their sources: Vitamin A: fish liver oil, carrots, butter and milk, so A-IV. Vitamin $\mathrm{B_{12}}$: meat, fish, egg and curd, so B-I. Vitamin E: vegetable oils such as wheat germ oil and sunflower oil, so C-II. Vitamin K: green leafy vegetables, so D-III. Match: A-IV, B-I, C-II, D-III, option (B).

3. Question 3 (NEET 2025)

   NEET 2025EasyCarbohydrates

   Sugar 'X' A. is found in honey. B. is a keto sugar. C. exists in α and β-anomeric forms. D. is laevorotatory. 'X' is :

   1. AOption A: D-Glucose
   2. BOption B: D-Fructose
   3. COption C: Maltose
   4. DOption D: Sucrose

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   Correct answer: (B) D-Fructose

   Explanation

   D-Fructose is present in honey, is a ketohexose sugar, exists in α and β anomeric forms, and is laevorotatory. Therefore, the correct answer is D-Fructose.

4. Question 4 (NEET 2024)

   NEET 2024MediumCarbohydrates

   The reagents with which glucose does not give the corresponding tests/products are: A. Tollen’s reagent B. Schiff’s reagent C. HCN D. NH₂OH E. NaHSO₃ Choose the correct options from the given below:

   1. AOption A: B and E
   2. BOption B: E and D
   3. COption C: B and C
   4. DOption D: A and D

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   Correct answer: (A) B and E

   Explanation

   Glucose exists mainly in cyclic hemiacetal form and does not respond to Schiff’s reagent. It also does not form sodium bisulphite addition product with NaHSO₃. However, glucose reacts with Tollen’s reagent, HCN and NH₂OH. Therefore, the correct pair is B and E. Hence, option (A) is correct.

5. Question 5 (NEET 2022)

   NEET 2022EasyProteins & Enzymes

   The incorrect statement regarding enzymes is:

   1. AOption A: Enzymes are very specific for a particular reaction and substrate
   2. BOption B: Enzymes are biocatalysts
   3. COption C: Like chemical catalysts enzymes reduce the activation energy of bio processes
   4. DOption D: Enzymes are polysaccharides

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   Correct answer: (D) Enzymes are polysaccharides

   Explanation

   Enzymes are mostly proteins (some are RNA catalysts), not polysaccharides. Hence option (D) is the incorrect statement.

6. Question 6 (NEET 2021)

   NEET 2021EasyProteins, Carbohydrates, Nucleic Acids and Lipids

   Match List-I with List-II. Choose the correct answer from the options given below.Match List-I with List-II. Choose the correct answer from the options given below.

   1. AOption A: (1) (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
   2. BOption B: (2) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
   3. COption C: (3) (a)-(i), (b)-(iv), (c)-(iii), (d)-(ii)
   4. DOption D: (4) (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

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   Correct answer: (B) (2) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)

   Explanation

   Correct matching: - Protein $\rightarrow$ Peptide bonds $(iv)$ - Unsaturated fatty acid $\rightarrow$ $C=C$ double bonds $(i)$ - Nucleic acid $\rightarrow$ Phosphodiester bonds $(ii)$ - Polysaccharide $\rightarrow$ Glycosidic bonds $(iii)$ Hence, the correct option is **(2)**.

7. Question 7 (NEET 2020)

   NEET 2020EasyProteins & Enzymes

   Which of the following is a basic α amino acid?

   1. AOption A: (1) Serine
   2. BOption B: (2) Alanine
   3. COption C: (3) Tyrosine
   4. DOption D: (4) Lysine

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   Correct answer: (D) (4) Lysine

   Explanation

   Lysine contains an extra amino group in its side chain, making it a basic α-amino acid.

8. Question 8 (NEET 2019)

   NEET 2019EasyArtificial Sweetening Agents

   The artificial sweetener stable at cooking temperature and does not provide calories is

   1. AOption A: Alitame
   2. BOption B: Saccharin
   3. COption C: Aspartame
   4. DOption D: Sucralose

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   Correct answer: (D) Sucralose

   Explanation

   Sucralose is a trichloro derivative of sucrose. It is stable at cooking temperature and does not provide calories.

9. Question 9 (AIPMT 2014)

   AIPMT 2014EasyArtificial Sweeteners

   Artificial sweetener which is stable under cold conditions only is:

   1. AOption A: Saccharine
   2. BOption B: Sucralose
   3. COption C: Aspartame
   4. DOption D: Alitame

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   Correct answer: (C) Aspartame

   Explanation

   Aspartame is unstable at high temperatures and loses its sweetness upon heating. Therefore it is generally used only in cold foods and beverages.

10. Question 10 (AIPMT 2009)

    AIPMT 2009EasyDrugs and Their Classification

    Which one of the following is employed as a tranquilizer?

    1. AOption A: Chlorpheniramine
    2. BOption B: Equanil
    3. COption C: Naproxen
    4. DOption D: Tetracycline

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    Correct answer: (B) Equanil

    Explanation

    Equanil (meprobamate) is used as a tranquilizer. Chlorpheniramine is an antihistamine, Naproxen is an analgesic, and Tetracycline is an antibiotic. Hence option (B) is correct.