NEET UG · Biology · Respiration in Plants

TCA Cycle: NEET previous year questions

8 questions in ten years of NEET, in 8 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 8; about 0.8 per paper
Years asked: 8/10; last asked 2025
Chance of a question next paper: 50%; historical rate, how we compute it
Weighted estimate: 0.7; model; history: 0.8 a paper on average, typically 0–1

Key findings

01
Asked in 8 of 10 papers, 8 questions in all: #108 of 204 topics by ten-year total. It comes back every 1.1 years on average. Last asked in 2025.
02
86% 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 GTP/ATP Synthesis, asked 2 times (2017, 2024), usually as “identify non-oxidative step in a pathway”.
04
NEET has asked 6 of the 93 ideas in this topic; 78 have never been asked, directly or indirectly.
05
Mostly asked as one-line MCQ (88%); 25% easy, 0% hard.

Questions per year

Up to 2023: 0.8; per paper
Since 2024: 0.6; -0.2
Usual gap: 1.1 yrs; between papers asking it
Swing: ±0.4; questions, year to year

How it is asked

Difficulty, format and skill

Across all 8 questions on TCA Cycle since 2017.

Difficulty

QUESTIONS

Easy2 · 25%
Medium6 · 75%
Hard0 · 0%

Format

One-line MCQ · 7 Q88%
Match the lists · 1 Q13%

Skill tested

Recall · 6 Q75%
Concept · 2 Q25%

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 6 of the 93 ideas in this topic. 78 have never been asked yet.

978

Asked directly6 · 6%
Touched inside another question9 · 10%
Never asked78 · 84%

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 · 25%25%2/10
- 2024 · Q141
  Identify the step in tricarboxylic acid cycle, which does not involve oxidation of substrate.
  mediumOne-line MCQ
- 2017 · Q138
  Which statement is wrong for Krebs' cycle ?
  mediumOne-line MCQNew idea
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%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

7 different ideas were tested; 1 came more than once. GTP/ATP Synthesis is the foundation for 33 other ideas in the syllabus.

GTP/ATP Synthesis2×
identify non-oxidative step in a pathway
One-line MCQ · 6% next · foundation for 33
Succinate Dehydrogenase Location1×
identify etc component by complex number
One-line MCQ · 6% next
Oxidative Decarboxylation Sites1×
match list on respiration steps
Match the lists · 4% next
NADH to ATP Equivalence1×
incorrect statement selection on respiration
One-line MCQ · 4% next
Substrate-Level vs Oxidative Phosphorylation1×
count of steps in a metabolic cycle
One-line MCQ · 4% next
Respiratory Quotient1×
numerical
One-line MCQ · 4% next
Matrix Location of TCA Enzymes1×
incorrect statement on respiration sites
One-line MCQ · 4% next · foundation for 1

Idea	Times	Format	Chance next	Foundation for
GTP/ATP Synthesisidentify non-oxidative step in a pathway	2	One-line MCQConcept	6%	33 ideas
Succinate Dehydrogenase Locationidentify etc component by complex number	1	One-line MCQRecall	6%	–
Oxidative Decarboxylation Sitesmatch list on respiration steps	1	Match the listsRecall	4%	–
NADH to ATP Equivalenceincorrect statement selection on respiration	1	One-line MCQRecall	4%	–
Substrate-Level vs Oxidative Phosphorylationcount of steps in a metabolic cycle	1	One-line MCQRecall	4%	–
Respiratory Quotientnumerical	1	One-line MCQRecall	4%	–
Matrix Location of TCA Enzymesincorrect statement on respiration sites	1	One-line MCQRecall	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

TCA Cycle questions, year by year

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

NEET 20251 question

Q91
The complex II of mitochondrial electron transport chain is also known as
Idea: Succinate Dehydrogenase Location
New ideaEasyOne-line MCQ

NEET 20241 question

Q141
Identify the step in tricarboxylic acid cycle, which does not involve oxidation of substrate.
Idea: GTP/ATP Synthesis
MediumOne-line MCQ

NEET 20231 question

Q148
Match List I with List II : List I | List II A. Oxidative decarboxylation | I. Citrate synthase B. Glycolysis | II. Pyruvate dehydrogenase…
Idea: Oxidative Decarboxylation Sites
New ideaMediumMatch the lists

NEET 20211 question

Q143
Which of the following statements is incorrect ?
Idea: NADH to ATP Equivalence
New ideaMediumOne-line MCQ

NEET 20201 question

Q85
The number of substrate level phosphorylations in one turn of citric acid cycle is :
Idea: Substrate-Level vs Oxidative Phosphorylation
New ideaEasyOne-line MCQ

NEET 20191 question

Q95
Respiratory Quotient (RQ) value of tripalmitin is :
Idea: Respiratory Quotient
New ideaMediumOne-line MCQ

NEET 20181 question

Q170
Which of these statements is incorrect ?
Idea: Matrix Location of TCA Enzymes
New ideaMediumOne-line MCQ

NEET 20171 question

Q138
Which statement is wrong for Krebs' cycle ?
Idea: GTP/ATP Synthesis
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.