NEET UG · Biology · Molecular Basis of Inheritance

Gene Regulation and the lac Operon: NEET previous year questions

7 questions in ten years of NEET, in 6 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 7; about 0.7 per paper
Years asked: 6/10; last asked 2026
Chance of a question next paper: 50%; historical rate, how we compute it
Weighted estimate: 0.7; model; history: 0.7 a paper on average, typically 0–1

Key findings

01
Asked in 6 of 10 papers, 7 questions in all: #121 of 204 topics by ten-year total. It comes back every 1.6 years on average.
02
57% of its questions since 2018 tested an idea never asked before; 1 repeated an idea from the year before.
03
The most repeated idea is lac z, y and a Gene Products, asked 3 times (2019, 2023, 2024), usually as “match list on lac operon genes”.
04
NEET has asked 0 of the 6 ideas in this topic; 0 have never been asked, directly or indirectly.
05
Mostly asked as one-line MCQ (71%); 14% easy, 0% hard.

Questions per year

Up to 2023: 0.7; per paper
Since 2024: 0.6; -0.0
Usual gap: 1.6 yrs; between papers asking it
Swing: ±0.6; questions, year to year

How it is asked

Difficulty, format and skill

Across all 7 questions on Gene Regulation and the lac Operon since 2017.

Difficulty

QUESTIONS

Easy1 · 14%
Medium6 · 86%
Hard0 · 0%

Format

One-line MCQ · 5 Q71%
Match the lists · 2 Q29%

Skill tested

Recall · 5 Q71%
Concept · 1 Q14%
Multi-step · 1 Q14%

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 0 of the 6 ideas in this topic. 0 have never been asked yet.

Asked directly0 · 0%
Touched inside another question6 · 100%
Never asked0 · 0%

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

Repeated3 · 43%43%3/10
- 2024 · Q101
  The lactose present in the growth medium of bacteria is transported to the cell by the action of:
  mediumOne-line MCQAsked the year before
- 2023 · Q151
  Match List I with List II. List I | List II A. Gene 'a' | I. β-galactosidase B. Gene 'y' | II. Transacetylase C. Gene 'i' | III. Permease…
  easyMatch the lists
- 2019 · Q166
  Match the following genes of the Lac operon with their respective products : (a) i gene | (i) β-galactosidase (b) z gene | (ii) Permease…
  mediumMatch the listsNew idea
Repeated2 · 29%29%2/10
1 · 14%14%1/10
1 · 14%14%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

4 different ideas were tested; 2 came more than once.

lac z, y and a Gene Products3×
match list on lac operon genes
Match the lists · 6% next
Inducer and Repressor Control2×
predict outcome of operon mutation
One-line MCQ · 6% next
Jacob and Monod's Operon Concept1×
match scientist with experiment or organism
One-line MCQ · 4% next
Structure of the lac Operon1×
odd-one-out among operon components
One-line MCQ · 4% next

Idea	Times	Format	Chance next	Foundation for
lac z, y and a Gene Productsmatch list on lac operon genes	3	Match the listsRecall	6%	–
Inducer and Repressor Controlpredict outcome of operon mutation	2	One-line MCQConcept	6%	–
Jacob and Monod's Operon Conceptmatch scientist with experiment or organism	1	One-line MCQRecall	4%	–
Structure of the lac Operonodd-one-out among operon components	1	One-line MCQRecall	4%	–

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

Gene Regulation and the lac Operon questions, year by year

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

NEET 20261 question

Q153
Which of the following statements about lac-operon is correct ?
Idea: Inducer and Repressor Control
MediumOne-line MCQ

NEET 20241 question

Q101
The lactose present in the growth medium of bacteria is transported to the cell by the action of:
Idea: lac z, y and a Gene Products
Asked last yearMediumOne-line MCQ

NEET 20231 question

Q151
Match List I with List II. List I | List II A. Gene 'a' | I. β-galactosidase B. Gene 'y' | II. Transacetylase C. Gene 'i' | III. Permease…
Idea: lac z, y and a Gene Products
EasyMatch the lists

NEET 20221 question

Q177
In an E.coli strain i gene gets mutated and its product can not bind the inducer molecule. If growth medium is provided with lactose, what…
Idea: Inducer and Repressor Control
New ideaMediumOne-line MCQ

NEET 20191 question

Q166
Match the following genes of the Lac operon with their respective products : (a) i gene | (i) β-galactosidase (b) z gene | (ii) Permease…
Idea: lac z, y and a Gene Products
New ideaMediumMatch the lists

NEET 20182 questions

Q109
Select the correct match :
Idea: Jacob and Monod's Operon Concept
New ideaMediumOne-line MCQ
Q158
All of the following are part of an operon except
Idea: Structure of the lac Operon
New ideaMediumOne-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.