NEET UG · Biology · Molecular Basis of Inheritance

DNA Double Helix: NEET previous year questions

16 questions in ten years of NEET, in 7 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 16; about 1.5 per paper
Years asked: 7/10; last asked 2025
Chance of a question next paper: 84%; historical rate, how we compute it
Weighted estimate: 1.4; model; history: 1.5 a paper on average, typically 0–3

Key findings

01
Asked in 7 of 10 papers, 16 questions in all: #31 of 204 topics by ten-year total. It comes back every 1.3 years on average. Last asked in 2025.
02
71% of its questions since 2018 tested an idea never asked before; none repeated an idea from the year before.
03
The most repeated idea is Euchromatin vs Heterochromatin, asked 2 times (2022, 2025), usually as “count correct statements on chromatin”.
04
NEET has asked 11 of the 84 ideas in this topic; 71 have never been asked, directly or indirectly.
05
Mostly asked as one-line MCQ (50%); 75% easy, 0% hard, and down from 1.8 to 1.0 questions a paper since 2024.

Questions per year

Up to 2023: 1.8; per paper
Since 2024: 1.0; -0.8
Usual gap: 1.3 yrs; between papers asking it
Swing: ±1.1; questions, year to year

Revise first

Euchromatin vs Heterochromatin (2022 2025); Histone Amino Acid Composition (2021 2025); RNA World Structural Evidence (2025)

How it is asked

Difficulty, format and skill

Across all 16 questions on DNA Double Helix since 2017.

Difficulty

QUESTIONS

124

Easy12 · 75%
Medium4 · 25%
Hard0 · 0%

Format

One-line MCQ · 8 Q50%
Two statements · 3 Q19%
Numerical · 3 Q19%
Match the lists · 1 Q6%
Other · 1 Q6%

Skill tested

Recall · 9 Q56%
Concept · 4 Q25%
Calculation · 3 Q19%

Repeats

New idea, or one asked before?

Each column is a paper. Blue questions tested an idea NEET had not asked before; navy ones went back to an idea from an earlier paper. 2017 is the first paper, so everything in it counts as new.

’17’18’19’20’21’22’23’24’25’26

Idea asked for the first time
Idea asked in an earlier paper

Coverage of the topic

NEET has asked 11 of the 84 ideas in this topic. 71 have never been asked yet.

1171

Asked directly11 · 13%
Touched inside another question2 · 2%
Never asked71 · 85%

Ideas come from Lumi’s syllabus map of NCERT. A never-asked idea is not a safe skip: most new questions come from exactly these.

Drill down

Idea, year, question

Every idea NEET tested in this topic, with its ten papers. Open one to read the questions.

ideaAskedShareYears’17’18’19’20’21’22’23’24’25’26

Repeated2 · 13%13%2/10
- 2022 · Q171
  If the length of a DNA molecule is 1.1 metres, what will be the approximate number of base pairs ?
  easyNumerical
- 2020 · Q74
  If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a DNA double helix in a typical…
  easyNumericalNew idea
Repeated2 · 13%13%2/10
Repeated2 · 13%13%2/10
Repeated2 · 13%13%2/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10
1 · 6%6%1/10

Squares are the ten papers, 2017 to 2026; darker means more questions. Share is of the level above.

Ideas

Every idea inside this topic

12 different ideas were tested; 4 came more than once. Nucleosome Structure is the foundation for 17 other ideas in the syllabus.

Euchromatin vs Heterochromatin2×
count correct statements on chromatin
Match the lists · 6% next
Histone Amino Acid Composition2×
identify wrong statement on histones
One-line MCQ · 6% next · foundation for 1
Hershey-Chase Experiment2×
identify scientist for a discovery
One-line MCQ · 6% next
DNA Length Calculation2×
numerical
Numerical · 6% next
RNA World Structural Evidence1×
statement i/ii on genetic material
Two statements · 6% next
Nucleosome Structure1×
statement i/ii on dna packaging
Two statements · 4% next · foundation for 17
RNA Mutation Rate1×
statement i/ii on rna genome mutation
Two statements · 4% next
Central Dogma1×
complete flow chart of process
One-line MCQ · 4% next · foundation for 3
Chargaff's Rules1×
numerical
Numerical · 4% next · foundation for 6
Hydrogen Bond Count1×
true statement selection on base pairing
One-line MCQ · 4% next · foundation for 2
Purines vs Pyrimidines1×
identify bases common to dna and rna
One-line MCQ · 4% next · foundation for 7
H1 Linker Histone1×
identify meaning of a structural association
One-line MCQ · 4% next · foundation for 1

Idea	Times	Format	Chance next	Foundation for
Euchromatin vs Heterochromatincount correct statements on chromatin	2	Match the listsConcept	6%	–
Histone Amino Acid Compositionidentify wrong statement on histones	2	One-line MCQRecall	6%	1 ideas
Hershey-Chase Experimentidentify scientist for a discovery	2	One-line MCQRecall	6%	–
DNA Length Calculationnumerical	2	NumericalCalculation	6%	–
RNA World Structural Evidencestatement i/ii on genetic material	1	Two statementsConcept	6%	–
Nucleosome Structurestatement i/ii on dna packaging	1	Two statementsRecall	4%	17 ideas
RNA Mutation Ratestatement i/ii on rna genome mutation	1	Two statementsConcept	4%	–
Central Dogmacomplete flow chart of process	1	One-line MCQRecall	4%	3 ideas
Chargaff's Rulesnumerical	1	NumericalCalculation	4%	6 ideas
Hydrogen Bond Counttrue statement selection on base pairing	1	One-line MCQRecall	4%	2 ideas
Purines vs Pyrimidinesidentify bases common to dna and rna	1	One-line MCQRecall	4%	7 ideas
H1 Linker Histoneidentify meaning of a structural association	1	One-line MCQConcept	4%	1 ideas

Chance next is the historical rate at which an idea with this record came back in the following paper. It is low for every idea, which is why learning the topic beats memorising past questions. All repeated ideas

Every question

DNA Double Helix questions, year by year

The opening words of each question as it appeared in the official paper, with the idea it tested.

NEET 20253 questions

Q96
Given below are two statements : Statement I : In the RNA world, RNA is considered the first genetic material evolved to carry out…
Idea: RNA World Structural Evidence
New ideaEasyTwo statements
Q134
Match List I with List II : List-I | List-II A. Alfred Hershey and Martha Chase | I. Streptococcus pneumoniae B. Euchromatin | II. Densely…
Idea: Euchromatin vs Heterochromatin
EasyMatch the lists
Q146
Histones are enriched with -
Idea: Histone Amino Acid Composition
EasyOne-line MCQ

NEET 20233 questions

Q118
Unequivocal proof that DNA is the genetic material was first proposed by
Idea: Hershey-Chase Experiment
EasyOne-line MCQ
Q181
Given below are two statements: Statement I: In prokaryotes, the positively charged DNA is held with some negatively charged proteins in a…
Idea: Nucleosome Structure
New ideaMediumTwo statements
Q184
Given below are two statements: Statement I: RNA mutates at a faster rate. Statement II: Viruses having RNA genome and shorter life span…
Idea: RNA Mutation Rate
New ideaEasyTwo statements

NEET 20222 questions

Q122
Read the following statements and choose the set of correct statements : (a) Euchromatin is loosely packed chromatin (b) Heterochromatin…
Idea: Euchromatin vs Heterochromatin
New ideaMediumOther
Q171
If the length of a DNA molecule is 1.1 metres, what will be the approximate number of base pairs ?
Idea: DNA Length Calculation
EasyNumerical

NEET 20213 questions

Q134
Complete the flow chart on central dogma. (a) [circular arrow on] DNA $\xrightarrow{(b)}$ mRNA $\xrightarrow{(c)}$ (d)
Idea: Central Dogma
New ideaEasyOne-line MCQ · figure
Q172
If Adenine makes 30% of the DNA molecule, what will be the percentage of Thymine, Guanine and Cytosine in it ?
Idea: Chargaff's Rules
New ideaEasyNumerical
Q190
Which one of the following statements about Histones is wrong ?
Idea: Histone Amino Acid Composition
New ideaMediumOne-line MCQ

NEET 20202 questions

Q74
If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a DNA double helix in a typical…
Idea: DNA Length Calculation
New ideaEasyNumerical
Q77
Which of the following statements is correct ?
Idea: Hydrogen Bond Count
New ideaEasyOne-line MCQ

NEET 20191 question

Q115
Purines found both in DNA and RNA are :
Idea: Purines vs Pyrimidines
New ideaEasyOne-line MCQ

NEET 20172 questions

Q100
The final proof for DNA as the genetic material came from the experiments of :
Idea: Hershey-Chase Experiment
EasyOne-line MCQ
Q124
The association of histone H1 with a nucleosome indicates :
Idea: H1 Linker Histone
MediumOne-line MCQ

Questions from the official NEET UG papers published by NTA (CBSE before 2019). Topic and idea tags, counts and notes are Lumi’s.