Are these the official NEET questions on Biomolecules?

Yes. They are the questions NTA set in each paper, in its wording. The solutions are written by BrainIt.

Biomolecules (Chemistry) NEET PYQs with Solutions (2020 to 2026) PDF

The questions come from NEET 2026, Re-NEET 2026 and NEET 2020. Each shows its answer and solution when you open it, so you can attempt it first. For what the chapter covers and how NEET tests it, see the Biomolecules guide.

Practise on the CBT screen6 questions, 6 minutes, marked +4 / −1 Download PDF3 pages, 0.7 MB, with answers and solutions

NEET 2026 · the full paper

NEET 2026 · Q51
The correct statement with regard to the secondary structure of DNA/RNA is
1. (1)
  RNA possesses a single strand helix structure and contains thymine as one of the four bases
2. (2)
  DNA possesses a double strand helix structure and contains thymine as one of the four bases
3. (3)
  RNA possesses a double strand helix structure and contains uracil as one of the four bases
4. (4)
  DNA possesses a single strand helix structure and contains uracil as one of the four bases
Answer and solution
Answer: (2)
DNA has a double-stranded helical secondary structure (two antiparallel polynucleotide chains) and its four bases are adenine, guanine, cytosine and thymine. RNA is generally single-stranded and contains uracil in place of thymine, so only the DNA statement pairing double-strand + thymine is correct.

Re-NEET 2026 · the full paper

Re-NEET 2026 · Q50
The correct statement about peptides and proteins is
1. (1)
  Tertiary structure of proteins has two or more polypeptide subunits
2. (2)
  Only the proteins having a quaternary structure are biologically active
3. (3)
  In $\beta$ -pleated sheet structures, peptide chains are held together by intermolecular hydrogen bonds
4. (4)
  In $\alpha$ -helices, the polypeptide chain is twisted into a left-handed screw (helix) through intramolecular hydrogen bonds
Answer and solution
Answer: (3)
In a $\beta$ -pleated sheet the polypeptide chains lie stretched side by side, and the hydrogen bonds run BETWEEN neighbouring chains - intermolecular. This is the key structural contrast with the $\alpha$ -helix, where the hydrogen bonds are intramolecular, formed within a single coiled chain. NCERT Class 12, Biomolecules (secondary structure of proteins).
Re-NEET 2026 · Q55
The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is
1. (1)
  leucine
2. (2)
  threonine
3. (3)
  methionine
4. (4)
  serine
Answer and solution
Answer: (3)
The sodium nitroprusside test detects SULPHUR: fusion with sodium converts organic sulphur to sulphide, which reacts with nitroprusside to give the intensely coloured complex $\mathrm{Na}_{4}[\mathrm{Fe}(\mathrm{CN})_{5}\mathrm{NOS}]$ . Of the four amino acids listed, only methionine contains sulphur - leucine is purely hydrocarbon in its side chain, while threonine and serine carry hydroxyl groups. NCERT Class 12, Biomolecules (amino acids); the detection method is from NCERT Class 11, Organic Chemistry: Some Basic Principles and Techniques.
Re-NEET 2026 · Q80
Match the vitamins in List I with their sources in List II.
List I
List II
P) vitamin A
I) meat
Q) vitamin $\text{B}_{12}$
II) sunflower oil
R) vitamin E
III) green leafy vegetables
S) vitamin K
IV) carrots
Choose the correct answer from the options given below.
1. (1)
  P-II, Q-III, R-IV, S-I
2. (2)
  P-IV, Q-I, R-II, S-III
3. (3)
  P-IV, Q-II, R-I, S-III
4. (4)
  P-III, Q-I, R-IV, S-II
Answer and solution
Answer: (2)
Carrots are rich in $\beta$ -carotene, the precursor of vitamin A (P-IV). Vitamin $\text{B}_{12}$ is essentially absent from plant foods and comes from animal sources such as meat (Q-I). Vitamin E is a fat-soluble antioxidant abundant in vegetable oils including sunflower oil (R-II). Vitamin K, needed for blood clotting, is supplied mainly by green leafy vegetables (S-III). NCERT Class 12, Biomolecules (vitamins).

List I	List II
P) vitamin A	I) meat
Q) vitamin $\text{B}_{12}$	II) sunflower oil
R) vitamin E	III) green leafy vegetables
S) vitamin K	IV) carrots

NEET 2020 · the full paper

NEET 2020 · Q91
Sucrose on hydrolysis gives
1. (1)
  $\alpha$ -D-Glucose + $\beta$ -D-Glucose
2. (2)
  $\alpha$ -D-Glucose + $\beta$ -D-Fructose
3. (3)
  $\alpha$ -D-Fructose + $\beta$ -D-Fructose
4. (4)
  $\beta$ -D-Glucose + $\alpha$ -D-Fructose
Answer and solution
Answer: (2)
Sucrose is made of an $\alpha$ -D-glucose unit and a $\beta$ -D-fructose unit joined through a glycosidic bond. On hydrolysis, this bond breaks to give glucose and fructose. The NEET 2020 keyed pair is $\alpha$ -D-glucose and $\beta$ -D-fructose.
NEET 2020 · Q121
Which of the following is a basic amino acid ?
1. (1)
  Alanine
2. (2)
  Tyrosine
3. (3)
  Lysine
4. (4)
  Serine
Answer and solution
Answer: (3)
Lysine is a basic amino acid due to the presence of an additional amino group ( $-\mathrm{NH}_{2}$ ) in its side chain, making it positively charged at physiological pH. Chapter: Biomolecules.

Practise Biomolecules in the app: it brings back the questions you get wrong, so the chapter improves, not just your memory of these. Or try the free CBT mock. All chapters: NEET chapter-wise PYQs.

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Biomolecules: NEET previous year questions

NEET 2026 · the full paper

Re-NEET 2026 · the full paper

NEET 2020 · the full paper

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