Key Fact
Glycolysis (EMP)
Cytoplasm; glucose (6C) → 2 pyruvate (3C). Net yield: 2 ATP, 2 NADH. Investment phase: 2 ATP used. Payoff phase: 4 ATP, 2 NADH. Rate-limiting enzyme: phosphofructokinase.
-- NCERT Class 11 Biology, Chapter 12, p. 156Respiration Glycolysis
8 MCQs9-step worked example
Source: NCERT Plant PhysiologyPYQ coverage: NEET 2022, 2023, 2026Official key: NTA-verifiedLast updated: 25 Sep 2026
Respiration Glycolysis, explained for NEET
The single most tested confusion about glycolysis is where it happens. Students who have spent weeks on mitochondrial pathways begin to assume every respiratory step occurs inside the mitochondrion. Glycolysis does not. It occurs in the cytoplasm (cytosol) of every living cell — prokaryotic or eukaryotic, aerobic or anaerobic. No membrane-bound organelle is required.
Glycolysis is a sequence of 10 enzyme-catalysed reactions that converts one molecule of glucose (6C) into two molecules of pyruvic acid (3C). The pathway is common to both aerobic and anaerobic respiration — it is the universal entry point.
Net yield per glucose molecule:
- 2 ATP (4 produced, 2 consumed in the preparatory phase)
- 2 NADH + H⁺
The pathway has two phases. The preparatory (energy-investment) phase (steps 1–5) phosphorylates glucose twice using 2 ATP, splitting the 6C sugar into two 3C molecules (glyceraldehyde-3-phosphate, G3P). The payoff (energy-harvest) phase (steps 6–10) oxidises G3P, generating 4 ATP by substrate-level phosphorylation and 2 NADH by reduction of NAD⁺.
Key NCERT fact: glycolysis was discovered by Gustav Embden, Otto Meyerhof, and Jakub Parnas — hence the name EMP pathway (NCERT Class 11 Biology Chapter 12, page 155).
Watch-out for NEET: When a question says "net gain of ATP in glycolysis," the answer is 2, not 4. When it asks "total ATP produced," the answer is 4. Read the stem word — net vs total — before marking.
Glycolysis does not require oxygen. Whether the cell is aerobic or anaerobic, glycolysis proceeds identically up to pyruvate. What happens to pyruvate after glycolysis depends on the organism and oxygen availability.
Can you answer these Respiration Glycolysis MCQs?
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
MCQ 1Easy RecallPractice
Glycolysis occurs in which part of the cell?
Show answer and why every option is right or wrong
Answer: A. Glycolysis takes place in the cytoplasm (cytosol) of the cell, not in any membrane-bound organelle. This is explicitly stated in NCERT Class 11 Biology, Chapter 12.
Why B is wrong: B is wrong because the mitochondrial matrix is the site of the Krebs cycle, not glycolysis. Confusing glycolysis location with Krebs cycle location is a common mistake (related: mistake: glycolysis location).
Why C is wrong: C is wrong because the inner mitochondrial membrane is the site of the electron transport chain (oxidative phosphorylation), not glycolysis.
Why D is wrong: D is wrong because the chloroplast stroma is the site of the Calvin cycle (dark reactions of photosynthesis), not glycolysis.
MCQ 2Easy RecallPractice
The net gain of ATP molecules during glycolysis from one molecule of glucose is:
Show answer and why every option is right or wrong
Answer: D. Glycolysis produces 4 ATP total but consumes 2 ATP in the preparatory phase, giving a net gain of 2 ATP per glucose molecule (NCERT Class 11 Biology, Chapter 12).
Why A is wrong: A is wrong because 4 is the total (gross) ATP produced, not the net gain. Two ATP are consumed in the energy-investment phase, so net = 4 − 2 = 2.
Why B is wrong: B is wrong because 8 ATP is not produced at any stage of glycolysis. This number has no basis in the pathway.
Why C is wrong: C is wrong because 1 ATP per glucose is not consistent with glycolysis. Each of the two 3C fragments generates 2 ATP in the payoff phase (total 4), minus 2 invested = net 2.
MCQ 3Easy RecallPractice
Glycolysis is also known as the EMP pathway. EMP stands for:
Show answer and why every option is right or wrong
Answer: B. The EMP pathway is named after Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas, who elucidated the glycolytic pathway (NCERT Class 11 Biology Chapter 12, page 155).
Why A is wrong: A is wrong because Pasteur studied fermentation but did not co-discover the glycolytic pathway. The 'P' stands for Parnas, not Pasteur.
Why C is wrong: C is wrong because EMP refers to the three scientists who discovered the pathway, not to enzyme names.
Why D is wrong: D is wrong because there is no 'Pauling' associated with the glycolysis discovery. Linus Pauling is known for chemical bonding and protein structure, not glycolysis.
MCQ 4Direct ApplicationPractice
During glycolysis, one molecule of glucose (6C) is broken down into:
Show answer and why every option is right or wrong
Answer: C. Glycolysis converts one 6-carbon glucose molecule into two 3-carbon pyruvic acid (pyruvate) molecules. This is the universal end-product of glycolysis regardless of aerobic or anaerobic conditions (NCERT Class 11 Biology, Chapter 12).
Why A is wrong: A is wrong because acetyl CoA is formed AFTER glycolysis — pyruvate is converted to acetyl CoA by pyruvate dehydrogenase in the mitochondrial matrix during the link reaction, not during glycolysis itself.
Why B is wrong: B is wrong because lactic acid is produced during anaerobic fermentation in animal cells AFTER glycolysis, not as a direct product of the glycolytic pathway.
Why D is wrong: D is wrong because ethanol is produced during alcoholic fermentation (in yeast) AFTER glycolysis. It is not a product of the glycolytic pathway itself, and the carbon accounting (3 × 2C = 6C) ignores the CO₂ released during decarboxylation.
MCQ 5Direct ApplicationPractice
Which of the following statements about glycolysis is correct?
Show answer and why every option is right or wrong
Answer: C. Glycolysis is the common first step in both aerobic and anaerobic respiration. It does not require oxygen at any step and occurs in the cytoplasm regardless of oxygen availability (NCERT Class 11 Biology, Chapter 12).
Why A is wrong: A is wrong because glycolysis occurs under BOTH aerobic and anaerobic conditions. It does not require oxygen — no step in the 10-reaction sequence uses O₂ as a substrate.
Why B is wrong: B is wrong because oxygen is not a substrate in any of the 10 glycolytic reactions. O₂ is consumed later in the electron transport chain, not in glycolysis.
Why D is wrong: D is wrong on two counts: glycolysis occurs in the CYTOPLASM (not mitochondria), and this is true under both aerobic and anaerobic conditions. The location does not change with oxygen availability (trap: mistake: glycolysis location).
MCQ 6Direct ApplicationPractice
In the preparatory phase of glycolysis, 2 ATP molecules are consumed. These ATP molecules are used for:
Show answer and why every option is right or wrong
Answer: A. The 2 ATP consumed in the preparatory phase phosphorylate glucose (step 1, by hexokinase) and fructose-6-phosphate (step 3, by phosphofructokinase), priming the sugar for subsequent cleavage into two 3C fragments (NCERT Class 11 Biology, Chapter 12).
Why B is wrong: B is wrong because NAD⁺ reduction to NADH occurs in the payoff phase (step 6) by the enzyme glyceraldehyde-3-phosphate dehydrogenase. This step does not consume ATP — it uses inorganic phosphate and NAD⁺.
Why C is wrong: C is wrong because pyruvate conversion to acetyl CoA is the link reaction (pyruvate dehydrogenase complex) that occurs in the mitochondrial matrix AFTER glycolysis, not during the preparatory phase.
Why D is wrong: D is wrong because oxidation of glyceraldehyde-3-phosphate occurs in the payoff phase (step 6) and does not consume ATP — it produces NADH.
MCQ 7CalculationPractice
If 10 molecules of glucose undergo complete glycolysis, the total number of NADH molecules produced and the total number of ATP molecules consumed in the preparatory phase are, respectively:
Show answer and why every option is right or wrong
Answer: D. Per glucose: 2 NADH produced and 2 ATP consumed. For 10 glucose molecules: 10 × 2 = 20 NADH and 10 × 2 = 20 ATP consumed (NCERT Class 11 Biology, Chapter 12).
Why A is wrong: A is wrong because it uses a multiplier of 1 instead of 2 for both NADH and ATP per glucose. Each glucose yields 2 NADH and consumes 2 ATP, so for 10 glucose molecules: 20 NADH and 20 ATP.
Why B is wrong: B is wrong because it undercounts NADH: each glucose gives 2 NADH, so 10 glucose give 20, not 10. Its ATP figure, 20, is right.
Why C is wrong: C is wrong because while the NADH count (20) is correct, the ATP consumed should also be 20 (2 per glucose × 10 = 20), not 10. This option halves the ATP investment.
MCQ 8Concept TrapPractice
A student claims that glycolysis cannot occur in red blood cells because mature mammalian RBCs lack mitochondria. This claim is:
Show answer and why every option is right or wrong
Answer: B. The student's claim is incorrect. Glycolysis occurs in the cytoplasm and requires no mitochondrial involvement. Mature mammalian RBCs rely entirely on glycolysis for ATP production precisely because they lack mitochondria (NCERT Class 11 Biology, Chapter 12).
Why A is wrong: A is wrong because glycolytic enzymes are cytoplasmic, not mitochondrial. No step of glycolysis occurs inside or requires the mitochondrion. This reflects the common mistake of placing glycolysis in mitochondria (mistake: glycolysis location).
Why C is wrong: C is wrong on two counts: glycolysis does NOT require oxygen (it is anaerobic), and the absence of mitochondria is irrelevant to glycolysis. Oxygen is needed for the ETC, not for glycolysis.
Why D is wrong: D is wrong because glycolytic enzymes are dissolved in the cytosol, not embedded in any membrane. There are no 'special' membrane-bound glycolysis enzymes in RBCs.
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How do you solve a Respiration Glycolysis question? A worked example
- 1
Given
A cell undergoes glycolysis of 5 glucose molecules under anaerobic conditions.
- 2
Required
Calculate: (a) total pyruvic acid molecules produced, (b) net ATP gained, (c) total NADH produced.
- 3
Concept
Glycolysis converts 1 glucose (6C) → 2 pyruvic acid (3C). Per glucose: gross ATP = 4, ATP consumed = 2, net ATP = 2, NADH produced = 2. These yields are identical under aerobic and anaerobic conditions — glycolysis itself does not use oxygen.
- 4
Formula
• Pyruvic acid = 2 × (number of glucose molecules)• Net ATP = 2 × (number of glucose molecules)• NADH = 2 × (number of glucose molecules)
- 5
Substitution
• Pyruvic acid = 2 × 5 = 10 molecules• Net ATP = 2 × 5 = 10 molecules• NADH = 2 × 5 = 10 molecules
- 6
Calculation
All multipliers here (2 and 5) are exact counting integers — they do not limit significant figures.
• Pyruvic acid produced: 10 molecules• Net ATP gained: 10 ATP• NADH produced: 10 NADH - 7
Final answer
From 5 glucose molecules undergoing glycolysis: 10 pyruvic acid, 10 net ATP, 10 NADH. The constants 2 (stoichiometric yield per glucose) and 5 (given glucose count) are exact integers and do not affect significant-figure analysis.
- 8
Common trap
The trap is confusing net with total ATP. Total ATP produced = 4 × 5 = 20, but 2 × 5 = 10 ATP are consumed in the preparatory phase. If the question says "net gain," the answer is 10, not 20. Read the stem carefully.
A second common trap: placing glycolysis in the mitochondria. The question said "anaerobic conditions," which might tempt students to think the pathway relocates — it does not. Glycolysis is always in the cytoplasm. - 9
Similar NEET-style question
"If 8 molecules of glucose undergo glycolysis, what is the net gain of ATP and the total NADH produced?" (Answer: 16 ATP net, 16 NADH)
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What to remember before solving Respiration Glycolysis questions
Where do students lose marks on Respiration Glycolysis?
These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Root cause: concept gap
Correction
Glycolysis is in CYTOPLASM (cytosol). Krebs cycle in mitochondrial matrix; ETC in inner membrane.
More in Plant Physiology: 4 exam traps and mistakes · 1 question pattern from its other lessons.
Respiration Glycolysis questions from past NEET papers
3 questions from NEET 2022, 2023, 2026. Answers verified against NTA official keys.
NEET 2026
1206
2309
3103
4412
NTA Answer: Option 4(final)
NEET 2023
1Both A and R are true but R is NOT the correct explanation of A.
2A is true but R is false.
3A is false but R is true.
4Both A and R are true and R is the correct explanation of A.
NTA Answer: Option 4(final)
NEET 2022
1Eight
2Four
3Six
4Two
NTA Answer: Option 4(final)
Sources
NCERT refs: Class 11 Biology Chapter 12, p.155
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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