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NEET Exam  >  NEET Test  >  Biology Class 11  >  Test: Introduction to Respiration, Glycolysis & Fermentation - NEET MCQ

Introduction to Respiration, Glycolysis & Fermentation - Free MCQ Practice


MCQ Practice Test & Solutions: Test: Introduction to Respiration, Glycolysis & Fermentation (15 Questions)

You can prepare effectively for NEET Biology Class 11 with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Introduction to Respiration, Glycolysis & Fermentation". These 15 questions have been designed by the experts with the latest curriculum of NEET 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 10 minutes
  • - Number of Questions: 15

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Test: Introduction to Respiration, Glycolysis & Fermentation - Question 1
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During glycolysis, the conversion of glucose to pyruvic acid occurs in which cellular location?

Detailed Solution: Question 1

The correct answer is Option B - Cytoplasm

Glycolysis is the metabolic pathway that converts glucose into pyruvate and operates in the cytosol (the fluid part of the cytoplasm) of both prokaryotic and eukaryotic cells.

The pathway functions without the need for oxygen (anaerobic in its initial steps) and therefore does not require mitochondrial compartments such as the matrix or cristae.

Per molecule of glucose, glycolysis yields a net of 2 ATP (by substrate-level phosphorylation), 2 NADH, and 2 pyruvate, all produced in the cytosolic compartment.

Under aerobic conditions the produced pyruvate is transported into the mitochondria for further oxidation; under anaerobic conditions it is reduced in the cytosol to regenerate NAD+.

Topic in NCERT: Glycolysis

Line in NCERT: "glycolysis occurs in the cytoplasm of the cell and is present in all living organisms."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 2
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Which of the following statements regarding respiration is correct?

  • Statement I: Respiration involves exchange of gases between organism and external environment.
  • Statement II: Cellular respiration occurs in cytoplasm and mitochondria only.

Detailed Solution: Question 2

The correct answer is Option B - Statement I is correct but Statement II is incorrect

Statement I is correct. External respiratory processes at respiratory surfaces allow oxygen (O₂) to enter the body and carbon dioxide (CO₂) to be removed, which matches the standard definition of the organism-environment gas exchange component of respiration.

Statement II is incorrect. In eukaryotic cells cellular respiration begins with glycolysis in the cytoplasm and continues in the mitochondria (including the Krebs cycle and oxidative phosphorylation), but many prokaryotes lack mitochondria and carry out respiration using their cytoplasm and the cell membrane; therefore it is not confined to only cytoplasm and mitochondria in all organisms.

Consequently, the first statement is true and the second statement is false, so the combined choice given above is the correct option.

Topic in NCERT: Cellular respiration

Line in NCERT: "the breaking of c-c bonds of complex organic molecules by oxidation cells leading to the release of a lot of energy is called cellular respiration."

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Test: Introduction to Respiration, Glycolysis & Fermentation - Question 3
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Match List-I with List-II:

Choose the correct answer from the options given below:

Detailed Solution: Question 3

The correct answer is Option A - A: (A)-(III), (B)-(I), (C)-(II), (D)-(IV)

  • Glycolysis converts one molecule of glucose into two molecules of pyruvic acid (pyruvate); therefore the product matched is pyruvic acid (III).

  • Alcoholic fermentation involves decarboxylation and reduction of pyruvate to form ethanol and CO2; hence the products are ethanol + CO2 (I).

  • Lactic acid fermentation reduces pyruvate to lactate (lactic acid) using NADH, so the product is lactate (II).

  • Aerobic respiration completely oxidises pyruvate in the presence of oxygen to produce CO2 and H2O, with overall energy (ATP) release; thus the products are CO2 + H2O (IV).

Topic in NCERT: Glycolysis

Line in NCERT: "pyruvic acid is then the key product of glycolysis."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 4
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Which of the following enzymes catalyzes the first step of glycolysis?

Detailed Solution: Question 4

The correct answer is Option B - Hexokinase

Hexokinase catalyses the initial step of glycolysis by adding a phosphate group to glucose, converting it into glucose-6-phosphate.

Glucose + ATP → Glucose-6-phosphate + ADP

This reaction occurs in the cytosol and the phosphorylation both activates glucose for further metabolism and effectively traps it inside the cell (phosphorylated sugars do not cross the membrane easily).

The step is effectively irreversible under physiological conditions; regulation of glycolysis later involves other enzymes (for example, phosphofructokinase-1 is a major rate-limiting control point). In liver cells, the same reaction is catalysed by the isozyme glucokinase, which differs in regulation from hexokinase.

Topic in NCERT: Glycolysis

Line in NCERT: "glucose is phosphorylated to give rise to glucose-6-phosphate by the activity of the enzyme hexokinase."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 5
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Consider the following statements about fermentation:
A. Fermentation is an anaerobic process
B. Fermentation produces less energy compared to aerobic respiration
C. Fermentation regenerates NAD+ for glycolysis to continue
D. Fermentation occurs in mitochondria
E. Fermentation produces only 2 ATP molecules per glucose

Which of the above statements are correct?

Detailed Solution: Question 5

The correct answer is Option B - A, B, C and E only

A is correct: fermentation is an anaerobic process that proceeds in the absence of molecular oxygen.

B is correct: fermentation yields much less energy than aerobic respiration; aerobic oxidation of one glucose gives about 30-32 ATP whereas fermentative (anaerobic) metabolism yields a net of only 2 ATP per glucose.

C is correct: fermentation regenerates NAD+ from NADH (for example by reducing pyruvate to lactate or to ethanol), which allows glycolysis to continue.

D is incorrect: fermentation occurs in the cytosol, not in the mitochondria; mitochondrial pathways are involved in aerobic respiration, not fermentative regeneration of cofactors.

E is correct (clarified): the net ATP yield per glucose under fermentative conditions is 2 ATP, produced during glycolysis; the subsequent fermentative reactions regenerate cofactors but do not produce additional ATP.

Topic in NCERT: Fermentation

Line in NCERT: "fermentation accounts for only a partial breakdown of glucose whereas in aerobic respiration it is completely degraded to co2 and h2o."
"in fermentation there is a net gain of only two molecules of atp for each molecule of glucose degraded to pyruvic acid whereas many more molecules of atp are generated under aerobic conditions."
"nadh is oxidised to nad* rather slowly in fermentation, however the reaction is very vigorous in case of aerobic respiration."
"fermentation takes place under anaerobic conditions in many prokaryotes, unicellular eukaryotes and in germinating seeds."
"under anaerobic conditions either lactic acid fermentation or alcohol fermentation occurs."
"in fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to co2 and ethanol."
"the reducing agent is nadh+h* which is reoxidised to nad+ in both the processes."
"in both lactic acid and alcohol fermentation not much energy is released; less than seven per cent of the energy in glucose is released and not all of it is trapped as high energy bonds of atp."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 6
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Which of the following is NOT a characteristic of glycolysis?

Detailed Solution: Question 6

The correct answer is Option B - It requires oxygen

  • Glycolysis takes place in the cytoplasm of the cell and converts one molecule of glucose into two molecules of pyruvate (2 pyruvate).

  • In the initial (investment) phase glycolysis consumes 2 ATP molecules; in the payoff phase it produces 4 ATP by substrate-level phosphorylation, giving a net yield of 2 ATP per glucose.

  • Glycolysis also produces 2 NADH per glucose as reducing equivalents.

  • Glycolysis is anaerobic in that it does not require oxygen to proceed; the fate of the produced NADH depends on cellular conditions (it is reoxidized by the electron transport chain when oxygen is available or by fermentation pathways in the absence of oxygen).

  • Because glycolysis does not need oxygen, the statement given in Option B is not a characteristic of this pathway.

Topic in NCERT: Glycolysis

Line in NCERT: "all living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen. this breakdown of glucose to pyruvic acid is called glycolysis."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 7
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In alcoholic fermentation, pyruvic acid is converted to ethanol through an intermediate compound. Identify the intermediate compound:

Detailed Solution: Question 7

The correct answer is Option A - Acetaldehyde

Pyruvic acid (pyruvate) is decarboxylated by the enzyme pyruvate decarboxylase with thiamine pyrophosphate (TPP) as a cofactor, producing acetaldehyde and CO2.

Acetaldehyde is then reduced to ethanol by alcohol dehydrogenase, using NADH as the reducing agent and regenerating NAD+.

From one molecule of glucose, glycolysis yields 2 pyruvate and 2 NADH; alcoholic fermentation converts these into 2 ethanol and 2 CO2, regenerating 2 NAD+ so glycolysis can continue, with a net gain of 2 ATP per glucose.

Acetyl CoA is produced in aerobic pyruvate oxidation, lactic acid is the product of lactic acid fermentation, and citric acid is an intermediate of the TCA cycle; therefore the correct intermediate for conversion to ethanol is acetaldehyde.

Topic in NCERT: Fermentation

Line in NCERT: "in fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to co2 and ethanol. the enzymes, pyruvic acid decarboxylase and alcohol dehydrogenase catalyse these reactions."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 8
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Match List-I with List-II:
List-I (Enzyme)List-II (Function in Glycolysis)
(A) Hexokinase(I) Converts PEP to pyruvate
(B) Phosphofructokinase(II) Phosphorylates glucose
(C) Pyruvate kinase(III) Phosphorylates fructose-6-phosphate
(D) Aldolase(IV) Splits fructose-1,6-bisphosphate

Choose the correct answer from the options given below:

Detailed Solution: Question 8

The correct answer is Option A - (A)-(II), (B)-(III), (C)-(I), (D)-(IV)

  • Hexokinase catalyses the phosphorylation of glucose to form glucose-6-phosphate, using ATP.
  • Phosphofructokinase catalyses the phosphorylation of fructose-6-phosphate to form fructose-1,6-bisphosphate; it is an important regulatory enzyme in glycolysis.
  • Pyruvate kinase converts phosphoenolpyruvate (PEP) to pyruvate, generating ATP in the process.
  • Aldolase cleaves fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP).

Topic in NCERT: Glycolysis

Line in NCERT: "hexokinase. this phosphorylated form of glucose then isomerises to produce fructose-6-phosphate."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 9
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Consider the following statements about lactic acid fermentation:
  • Statement I: Lactic acid fermentation occurs in muscle cells during strenuous exercise when oxygen supply is limited.
  • Statement II: In lactic acid fermentation, pyruvic acid is directly reduced to lactic acid by NADH.

Which of the above statements is/are correct?

Detailed Solution: Question 9

The correct answer is Option C - Both Statement I and Statement II

Under conditions of high energy demand when mitochondrial respiration cannot supply enough ATP, certain skeletal muscle fibres switch to an anaerobic pathway in the cytosol that converts pyruvate to lactate, allowing continued ATP production by glycolysis.

The biochemical step responsible is the reduction of pyruvate by NADH; this reaction is catalysed by the enzyme lactate dehydrogenase and can be written as pyruvate + NADH + H+ → lactate + NAD+.

The critical physiological role of this reaction is regeneration of NAD+, which is required for glycolysis to continue producing a small but rapid supply of ATP under low-oxygen (anaerobic) conditions; the lactate produced can later be processed by the liver.

Topic in NCERT: Fermentation

Line in NCERT: "in animal cells also, like muscles during exercise, when oxygen is inadequate for cellular respiration pyruvic acid is reduced to lactic acid by lactate dehydrogenase."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 10
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Which of the following statements regarding cellular respiration is correct?
A. Glycolysis can occur in the presence or absence of oxygen
B. Fermentation is more efficient than aerobic respiration in ATP production
C. The exchange of gases occurs at the cellular level during cellular respiration
D. Pyruvic acid is the end product of glycolysis
E. Alcoholic fermentation produces lactic acid

Detailed Solution: Question 10

The correct answer is Option B - A, C and D only

  • Statement A is correct. Glycolysis occurs in the cytoplasm and can proceed in both the presence and absence of oxygen; when oxygen is absent its products enter pathways of fermentation.

  • Statement B is incorrect. Fermentation yields about 2 ATP per glucose, whereas aerobic respiration yields roughly 30-32 ATP per glucose, so fermentation is much less efficient in ATP production.

  • Statement C is correct. At the cellular level cells take up O₂ and release CO₂ by diffusion; these gas movements occur where the respiratory reactions take place inside cells.

  • Statement D is correct. The end product of glycolysis is pyruvic acid (pyruvate); glycolysis also yields a net of 2 ATP and 2 NADH per glucose.

  • Statement E is incorrect. Alcoholic fermentation produces ethanol and carbon dioxide, while lactic acid is produced in lactic acid fermentation.

Topic in NCERT: Glycolysis

Line in NCERT: "each glucose molecule is broken through a series of enzyme catalysed reactions into two molecules of pyruvic acid. this process is called glycolysis."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 11
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Which enzymes are responsible for converting pyruvic acid to ethanol and CO2 during alcoholic fermentation in yeast?

Detailed Solution: Question 11

In alcoholic fermentation, pyruvic acid is converted into ethanol and CO2 under anaerobic conditions. The enzymes catalyzing these reactions are pyruvic acid decarboxylase and alcohol dehydrogenase.

Topic in NCERT: Fermentation

Line in NCERT: "the enzymes, pyruvic acid decarboxylase and alcohol dehydrogenase catalyse these reactions."

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 12
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Assertion (A): Respiration is a stepwise oxidation of food inside the cell rather than a single-step combustion.
Reason (R): If glucose were oxidised in one step, all energy would be released as heat and could not be trapped as ATP.

Detailed Solution: Question 12

Respiration involves controlled, enzyme-mediated stepwise oxidation of glucose. If oxidation occurred in a single step like combustion, the released energy would dissipate as heat and could not be efficiently trapped as ATP. Therefore, both the assertion and reason are correct, and the reason explains the assertion.

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 13
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Assertion (A): Fermentation yields much less ATP than aerobic respiration.
Reason (R): In fermentation, glucose undergoes complete oxidation to CO₂ and H₂O.

Detailed Solution: Question 13

Fermentation produces only 2 ATP per glucose molecule and involves partial breakdown of glucose. Complete oxidation to CO₂ and H₂O occurs only during aerobic respiration. Thus, the assertion is true, but the reason is false.

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 14
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Arrange the following steps of glycolysis in the correct sequence:
1. Formation of fructose-1,6-bisphosphate
2. Formation of glucose-6-phosphate
3. Formation of fructose-6-phosphate
4. Splitting into triose phosphates

Detailed Solution: Question 14

Glucose is first phosphorylated to glucose-6-phosphate. It is then isomerised to fructose-6-phosphate. This is phosphorylated to form fructose-1,6-bisphosphate, which is finally split into two triose phosphates. Hence, the correct order is 2 → 3 → 1 → 4.

Test: Introduction to Respiration, Glycolysis & Fermentation - Question 15
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Arrange the following events in correct order during alcoholic fermentation:
1. Regeneration of NAD⁺
2. Formation of acetaldehyde
3. Release of CO₂
4. Reduction of acetaldehyde to ethanol

Detailed Solution: Question 15

In alcoholic fermentation, pyruvate is first decarboxylated to form acetaldehyde, releasing CO₂. Acetaldehyde is then reduced to ethanol, during which NADH is oxidised to regenerate NAD⁺. Therefore, the correct sequence is 2 → 3 → 4 → 1.

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This test contains 15 MCQs on Introduction to Respiration, Glycolysis & Fermentation with detailed solutions for each question. It is part of the Biology Class 11 course on EduRev, designed to align with the current NEET syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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