Respiration in Plants: NEET MCQ Questions [100+ Solved]

Below are the NEET MCQ questions on Class 11 Biology Chapter “Respiration in Plants” based on the NCERT textbook. Solve the below free NEET mock test for a better understanding of the various topics. 100+ important MCQs (multiple choice questions) are given in this NEET question bank.

“Respiration in Plants” is the 14th chapter in the unit “Plant Physiology” of class XI or class 11th Biology NCERT. Do note that NEET (which is conducted by NTA) is based on NCERT textbooks so they are a must-have. You can also download PDFs of NCERT textbooks.

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Which of the following is an essential feature of respiration?
(a) It liberates energy
(b) It provides O2
(c) Utilize CO2
(d) Synthesize complex compounds

(a) It liberates energy

In cellular respiration, what role does molecular oxygen play?
(a) It causes the breakdown of citric acid.
(b) To combine with glucose to produce carbon dioxide.
(c) To combine with carbon from organic molecules to produce carbon dioxide.
(d) To combine with hydrogen from organic molecules to produce water.

(d) To combine with hydrogen from organic molecules to produce water.

What enzyme is inhibited by an excess of ATP?
(a) Phosphofructokinase
(b) Hexokinase
(c) Aldolase (Lyases)
(d) Pyruvate decarboxylase

(a) Phosphofructokinase

In the process of making bread, it becomes porous due to the release of CO2 by the action of?
(a) Yeast
(b) Bacterial
(c) Virus
(d) Protozoans

(a) Yeast

What is respiration?
(a) anabolic + exergonic
(b) catabolic + exergonic
(c) catabolic + endergonic
(d) anabolic + endergonic

(b) catabolic + exergonic

What is the product of aerobic respiration?
(a) Malic acid
(b) Ethyl alcohol
(c) Lactic acid
(d) Pyruvic acid

(a) Malic acid

In glycolysis, what removes electrons during oxidation?
(a) Molecular oxygen
(b) ATP
(c) Glyceraldehyde
(d) NAD+

(d) NAD+

When 1 mole of pyruvate is completely oxidized, how many moles of carbon dioxide are produced?
(a) 1
(b) 2
(c) 3
(d) 4

During the early stages of alcoholic fermentation there is a high rate of yeast growth. After some time the rate decreases. Which of the following conditions in the culture medium is least likely to have caused this?
(a) Depletion of glucose
(b) Depletion of oxygen
(c) Depletion of mineral salts
(d) Accumulation of waste products

(b) Depletion of oxygen

Certain organisms are allowed to respire anaerobically for some time. When these organisms are transferred to an oxygen-containing medium, their aerobic respiration rate is always faster than the rate of respiration of organisms which are given oxygen from the beginning. This is due to
(a) Due to a faster rate of oxidation, the end products accumulate in the aerobic organisms, reducing the rate of their respiration
(b) In anaerobically respiring animals there are extra enzymes to increase the rate of the oxidation
(c) In anaerobically respiring animals the end product produced is common with that of aerobic respiration and
therefore the rate of oxidation is hastened
(d) In aerobically respiring organisms an intermediate product of anaerobic respiration is further oxidized.

(d) In aerobically respiring organisms an intermediate product of anaerobic respiration is further oxidized.

What is the R.Q. in anaerobic respiration?
(a) 0
(b) ∞
(c) 1
(d) 1

(b) ∞

What is the basis of the chemiosmotic theory of ATP synthesis in chloroplasts and mitochondria?
(a) membrane potential
(b) accumulation of Na ions
(c) accumulation of K ions
(d) proton gradient

(d) proton gradient

In which stage of complete glucose oxidation do the most ATP molecules form from ADP?
(a) glycolysis
(b) Krebs cycle
(c) conversion of pyruvic acid to acetyl Co-A
(d) electron transport chain

(d) electron transport chain

During glycolysis, what catalyses the phosphorylation of glucose?
(a) phosphoglucomutase
(b) phosphoglucoisomerase
(c) hexokinase
(d) phosphorylase

Pyruvic acid, the key product of glycolysis can have many metabolic fates. What does it form under aerobic conditions?
(a) lactic acid
(b) CO2 + H2O
(c) acetyl Co – A + CO2
(d) ethanol + CO2

The location of the electron Transport System (ETS) is in the mitochondrial
(a) outer membrane
(b) intermembrane space
(c) inner membrane
(d) matrix

Which of the following exhibits the greatest rate of respiration?
(a) Growing shoot apex
(b) Germinating seed
(c) Root tip
(d) Leaf bud

(b) Germinating seed

Choose the correct statement.
(a) Pyruvate is formed in the mitochondrial matrix.
(b) During the conversion of succinyl Co-A to succinic acid a molecule of ATP is synthesized.
(c) Oxygen is vital in respiration for the removal of hydrogen.
(d) There is a complete breakdown of glucose in fermentation.

(a) Pyruvate is formed in the mitochondrial matrix.

Mitochondria are called powerhouses of the cell. This statement is supported by which of the following observations?
(a) Mitochondria synthesise ATP
(b) Mitochondria have a double membrane
(c) The enzymes of the Krebs’ cycle and the cytochromes are found in mitochondria
(d) Mitochondria are found in almost all plants and animal cells.

(a) Mitochondria synthesise ATP

What must a bacteria do to continue growing rapidly when they are shifted from an environment containing O2 to an anaerobic environment?
(a) produce more ATP per mole of glucose during glycolysis.
(b) produce ATP during the oxidation of glucose.
(c) increase the rate of glycolysis.
(d) increase the rate of the TCA cycle.

What is the major reason that glycolysis is not as energy productive as respiration?
(a) NAD+ is regenerated by alcohol or lactate production, without the high-energy electrons passing through the electron transport chain.
(b) it is the pathway common to fermentation and respiration.
(c) it does not take place in a specialized membrane-bound organelle.
(d) pyruvate is more reduced than CO2; it still contains much of the energy from glucose.

(d) pyruvate is more reduced than CO2; it still contains much of the energy from glucose.

When is a protein used as a respiratory substrate?
(a) Carbohydrates are absent
(b) Fats are absent
(c) Both carbohydrates and fats are exhausted
(d) Fats and carbohydrates are abundant

What mediates the conversion of pyruvic acid into ethyl alcohol?
(a) Phosphatase
(b) Dehydrogenase
(c) Decarboxylase & dehydrogenase
(d) Catalase

Fructose-1,6-diphosphate is broken down by which enzyme?
(a) Hexokinase
(b) Phosphatase
(c) Aldolase
(d) None of these

Pyruvate (pyruvic) dehydrogenase is used in converting?
(a) pyruvate to glucose
(b) glucose to pyruvate
(c) pyruvic acid to lactic acid
(d) pyruvate to acetyl coA

(d) pyruvate to acetyl coA

In respiration, what is the last electron receptor?
(a) CO2
(b) O2
(c) H2
(d) NADH

(b) O2

What happens when 2-pyruvic acids form two lactic acids by anaerobic respiration?
(a) One ATP is lost
(b) 3 ATP is lost
(c) 6 ATP is lost
(d) None of these

Which of the following is coenzyme II?
(a) NAD
(b) NADP
(c) FAD
(d) None of these

(b) NADP

Where does glycolysis occur?
(a) mitochondria
(b) chloroplast
(c) cytoplasm
(d) peroxisome

When anaerobic respiration occurs after glycolysis, what is it called?
(a) fermentation
(b) fragmentation
(c) restoration
(d) multiplication

(a) fermentation

The glucose molecule is converted into what in glycolysis?
(a) PEP
(b) RuBP
(c) acetyl CoA
(d) pyruvic acid

(d) pyruvic acid

Where does photorespiration begin in C3 plants?
(a) phosphoglycerate
(b) phosphoglycolate
(c) glycerate
(d) glycine

(a) phosphoglycerate

Glycolysis and the Krebs cycle are connected by which of the following?
(a) Acetyl CoA
(b) Oxalosuccinic acid
(c) Pyruvic acid
(d) Citric acid

(a) Acetyl CoA

All enzymes of the TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and in the cytosol in prokaryotes. Which is this enzyme?
(a) isocitrate dehydrogenase
(b) malate dehydrogenase
(c) succinate dehydrogenase
(d) lactate dehydrogenase.

What is the energy-releasing process in which the substrate is oxidised without an external electron acceptor called?
(a) fermentation
(b) photorespiration
(c) aerobic respiration
(d) glycolysis

(d) glycolysis

Why are sugars not as good as fats as a source of energy for cellular respiration?
(a) produce toxic amino groups when broken down.
(b) contain more hydrogen.
(c) usually bypass glycolysis and the Krebs cycle.
(d) contain fewer hydrogen atoms and electrons.

(d) contain fewer hydrogen atoms and electrons.

When one molecule of glucose is oxidized in aerobic respiration, what is formed?
(a) 36 ATP molecules
(b) 38 ATP molecules
(c) 3 ATP molecules
(d) 15 ATP molecules

(b) 38 ATP molecules

What reaction is incorrectly paired with its location?
(a) ATP synthesis/inner membrane of the mitochondrion.
(b) Fermentation/cell cytosol
(c) Glycolysis/cell cytosol
(d) Krebs cycle/cristae of the mitochondrion

(d) Krebs cycle/cristae of the mitochondrion

Glucose, made from six radioactively labelled carbon atoms, is fed to yeast cells in the absence of oxygen. From one molecule of glucose, how many molecules of radioactive alcohol (C2H5OH) are formed?
(a) 0
(b) 1
(c) 2
(d) 3

Which of the following can inhibit the enzyme cytochrome oxidase?
(a) Iodoacetate
(b) Azides & Cyanides
(c) Oligonlycins
(d) Dinitrophenol

(d) Dinitrophenol

Aerobic oxidation of pyruvate requires how many oxygen atoms?
(a) 6
(b) 8
(c) 10
(d) 12

What is the link between glycolysis & TCA cycle?
(a) Pyruvic acid
(b) Acetyl Co-A
(c) Citric acid
(d) None of these

(b) Acetyl Co-A

The chemiosmotic coupling hypothesis of oxidative phosphorylation proposes that ATP is formed because?
(a) high energy bonds are formed in mitochondrial proteins
(b) ADP is pumped out of the matrix into the intermembrane space
(c) a proton gradient forms across the inner membrane
(d) there is a change in the permeability of the inner mitochondrial membrane toward adenosine diphosphate (ADP)

When substrate is oxidized without an external electron acceptor, what is the energy-releasing metabolic process called?
(a) glycolysis
(b) fermentation
(c) aerobic respiration
(d) photorespiration

(b) fermentation

Where are respiratory enzymes located?
(a) Mitochondrial matrix (mitochondria)
(b) Perimitochondrial space
(c) Cristae
(d) Outer membrane

(a) Mitochondrial matrix (mitochondria)

In which of the following reactions is FADH2 produced?
(a) Succinic acid to fumaric acid
(b) Fumaric acid to malic acid
(c) Succinyl Co-A to succinic acid
(d) Isocitric acid to oxaloacetic acid

(a) Succinic acid to fumaric acid

An intermediary compound of the Krebs cycle, oxalosuccinic acid, is a
(a) 6 carbon compound
(b) 5 carbon compound
(c) 3 carbon compound
(d) 4 carbon compound

(a) 6 carbon compound

In aerobic cellular respiration, protein molecules are used as fuel and _ are produced as waste.
(a) amino groups
(b) fatty acids
(c) sugar molecules
(d) molecules of lactic acid

(a) amino groups

Glycolysis is considered one of the first metabolic pathways to have evolved. Why?
(a) It relies on fermentation, which is characteristic of the archaebacteria and eubacteria.
(b) It produces much less ATP than does the electron transport chain and chemiosmosis.
(c) It relies totally on enzymes that are produced by free ribosomes, and bacteria have only free ribosomes and no bound ribosomes.
(d) It is nearly universal, is located in the cytosol, and does not involve O2.

(d) It is nearly universal, is located in the cytosol, and does not involve O2.

What catalyses the conversion of fructose–6–phosphate to fructose 1, 6-diphosphate?
(a) Phosphofructose kinase
(b) Aldolase
(c) Hexokinase
(d) None of these

(a) Phosphofructose kinase

The oxidation of one mole of glucose to CO2 and H2O yields 686 kcal, and the useful chemical energy stored in the high-energy phosphate bond of one mole of ATP is 12 kcal. How many ATP molecules could maximally be generated from one molecule of glucose?
(a) Thirty
(b) Fifty-seven
(c) One
(d) Two

(b) Fifty-seven

ADP forms the most energy-deriving molecules (ATP) during which stage of the complete oxidation of glucose?
(a) Conversion of pyruvic acid to acetyl CoA
(b) Electron transport chain
(c) Glycolysis
(d) Krebs cycle

(b) Electron transport chain

What is the chemiosmotic theory of ATP synthesis based on?
(a) Proton gradient
(b) Accumulation of K ions
(c) Accumulation of Na ions
(d) Membrane potential

(a) Proton gradient

How much ATP is generated by each pair of electrons that pass from NADH molecules through a sequential series of cytochrome enzymes on the way to molecular oxygen in the mitochondrial electron transport system?
(a) 3 ATP
(b) 4 ATP
(c) 6 ATP
(d) 2 ATP

Which statement about ATP synthesis is true?
(a) ATP can be synthesized through substrate-level phosphorylation, photophosphorylation and oxidative phosphorylation.
(b) The proton-motive force is the establishment of proton gradients and electrochemical potentials across the inner membrane.
(c) Proton-motive force is essential for the backflow of H+ from the outer chamber of a matrix of mitochondria through the proton channel (F0) of F0 – F1 particle to produce ATP.
(d) All of the above

(d) All of the above

What process uses oxygen directly?
(a) Glycolysis
(b) Fermentation
(c) Electron transport
(d) Krebs citric acid cycle

The inner mitochondrial membrane has complex V of the ETS. Which one is it?
(a) NADH dehydrogenase
(b) Cytochrome c oxidase
(c) Ubiquinone
(d) ATP synthetase

(d) ATP synthetase

Which is a 4-carbon compound?
(a) Oxaloacetic acid
(b) Citric acid
(c) Phosphoglyceric acid
(d) Phosphoenol pyruvate

(a) Oxaloacetic acid

Respiration in plants requires which of the following?
(a) Carbon dioxide
(b) Oxygen
(c) Chlorophyll
(d) Light

(b) Oxygen

A combination of the lowest and highest energy molecule is found in which pair?
(a) Glucose and pyruvic acid
(b) Acetyl CoA and palmitic acid
(c) Glucose and malic acid
(d) Malic acid and acetyl CoA

(b) Acetyl CoA and palmitic acid

What is the R.Q. for glucose (Carbohydrates)?
(a) 1
(b) 0.5
(c) 2
(d) 0.05

(a) 1

What does it mean if R. Q. is less than 1.0 in respiratory metabolism?
(a) Carbohydrates are used as a respiratory substrate
(b) Organic acids are used as a respiratory substrate
(c) The oxidation of the respiratory substrate consumed more oxygen than the amount of CO2 released
(d) The oxidation of the respiratory substrate consumed less oxygen than the amount of CO2 released

What is the R.Q. value of Oxalic acid?
(a) 1.0
(b) 0.7
(c) 1.5
(d) ∞

What is the first stage of glucose breakdown in animal cells?
(a) Krebs cycle
(b) glycolysis
(c) oxidative phosphorylation
(d) electron transport chain

(b) glycolysis

In an aerobic organism, what is the ultimate electron acceptor of respiration?
(a) cytochrome
(b) oxygen
(c) hydrogen
(d) glucose

(b) oxygen

How is acetyl CoA produced from pyruvate?
(a) oxidative decarboxylation
(b) oxidative photophosphorylation
(c) oxidative hydrogenation
(d) oxidative photorespiration

(a) oxidative decarboxylation

Which carrier transfers the electrons in the electron transport system?
(a) phytochrome
(b) cytochrome
(c) quantasomes
(d) fucoxanthin

(b) cytochrome

The EMP pathway of glycolysis was discovered by which group of scientists?
(a) Embden, Meyerhof and Parnas
(b) Emerson, Hoffman and Peterson
(c) Embden, Morrison and Pitcher
(d) Avery, McLeod and McCarthy

(a) Embden, Meyerhof and Parnas

Pyruvic acid is formed from Acetyl Co-A due to the result of its?
(a) Reduction
(b) Dehydration
(c) Phosphorylation
(d) Oxidative decarboxylation

(d) Oxidative decarboxylation

Which statement about mitochondrial membrane is false?
(a) The inner membrane is highly convoluted forming a series of infoldings
(b) The outer membrane resembles a sieve
(c) The outer membrane is permeable to all kinds of molecules
(d) The enzymes of the electron transfer chain are embedded in the outer membrane

(d) The enzymes of the electron transfer chain are embedded in the outer membrane

What type of mammalian cell does not carry out oxidative phosphorylation?
(a) Cardiac muscle cells
(b) Erythrocytes
(c) Neurons
(d) Oxyntic cells

(b) Erythrocytes

The “Mitchell’s chemiosmotic theory” belongs to the?
(a) Kreb’s cycle
(b) oxidative phosphorylation
(c) glycolysis
(d) None of the above

(b) oxidative phosphorylation

All carbon atoms obtained from carbohydrates, lipids, and proteins that are oxidized during respiration follow what final pathway?
(a) The Calvin cycle
(b) The electron transport system
(c) The Krebs cycle
(d) The ornithine cycle

The reason why oxidation of a molecule of FADH2 yields less ATP than a molecule of NADH yields is because FADH2
(a) carries fewer electrons.
(b) is formed in the cytosol and energy is lost when it shuttles its electrons across the mitochondrial membrane.
(c) passes its electrons to a transport molecule later in the chain and at a lower energy level.
(d) is the last molecule produced by the Krebs cycle, and little energy is left to be captured.

In the tricarboxylic acid cycle, which substance is not an essential component?
(a) FAD
(b) Succinyl CoA
(c) NADP
(d) Citric acid

Why does the amount of CO2 in the atmosphere remain relatively constant if CO2 is released in respiration?
(a) CO2 forms carbonate rocks.
(b) CO2 is a buffer.
(c) CO2 is converted in photosynthesis to carbohydrates.
(d) CO2 splits up during photosynthesis.

What is decarboxylation not involved in?
(a) electron transport system
(b) glycolysis
(c) Kreb’s cycle
(d) alcoholic fermentation

(b) glycolysis

The electron carrier molecules Q and cytochrome c
(a) are reduced as they pass electrons on to the next molecule.
(b) contain heme prosthetic groups.
(c) shuttle protons to ATP synthase.
(d) are mobile carriers that transfer electrons between the electron carrier complexes.

(d) are mobile carriers that transfer electrons between the electron carrier complexes.

How many carbon atoms are present in citric acid?
(a) 8
(b) 6
(c) 10
(d) 2

(b) 6

Which of the following is complex V of the inner mitochondrial membrane ETS?
(a) NADH dehydrogenase
(b) Cytochrome c oxidase
(c) Ubiquinone
(d) ATP synthase

(d) ATP synthase

Oxygen is directly used in which of the following processes?
(a) Glycolysis
(b) Fermentation
(c) Electron transport
(d) Krebs citric acid cycle

Amino acid synthesis involves which intermediate compound?
(a) Malic acid
(b) Citric acid
(c) a-ketoglutaric acid
(d) Isocitric acid

What causes the oxidation of succinate to fumarate in Kreb’s cycle?
(a) Loss of electron from it
(b) Removal of hydrogen from it
(c) Addition of oxygen to it
(d) None of the above

(b) Removal of hydrogen from it

Which of the following cytochromes reacts with oxygen in the electron transport system (ETS)?
(a) Cyt b
(b) Cyt a3
(c) Cyt b6
(d) Cyt f

(b) Cyt a3

Which cytochrome donates electrons to O2 in an electron transport chain in terminal oxidation?
(a) Cytochrome b
(b) Cytochrome c
(c) Cytochrome a3
(d) Cytochrome a

What is the end product of oxidative phosphorylation?
(a) NADH
(b) oxygen
(c) ADP
(d) ATP + H2O

(d) ATP + H2O

The respiration-mediated breakdown of fats, carbohydrates, and proteins is common to which of these metabolites?
(a) Fructose 1, 6 – bisphosphate
(b) Pyruvic acid
(c) Acetyl CoA
(d) Glucose – 6 – phosphate

CO2 is not released in which one of the following processes?
(a) Aerobic respiration in plants
(b) Aerobic respiration in animals
(c) Alcoholic fermentation
(d) Lactate fermentation

(d) Lactate fermentation

What are specialised epidermal cells surrounding the guard cells called?
(a) Complementary cells
(b) Subsidiary cells
(c) Bulliform cells
(d) Lenticels

(b) Subsidiary cells

In Kreb’s-cycle, what is the acceptor of acetyl Co-A?
(a) Malic acid
(b) Fumaric acid
(c) a-ketoglutaric acid
(d) Oxalo acetic acid

(d) Oxalo acetic acid

What is the energy coin of a cell?
(a) DNA
(b) RNA
(c) ATP
(d) Minerals

Pyruvate dehydrogenase complex is used to convert?
(a) Pyruvate to glucose
(b) Glucose to pyruvate
(c) Pyruvic acid to lactic acid
(d) Pyruvate to acetyl Co-A

(d) Pyruvate to acetyl Co-A

When it comes to respiration, which of the following statements is more accurate?
(a) O2 must always be available for respiration.
(b) O2 combines with carbon to form CO2.
(c) O2 combines with hydrogen to form H2O.
(d) Air is inhaled and exhaled only from the stomata.

Where does the process of oxidative phosphorylation take place?
(a) Mitochondria
(b) Chloroplasts
(c) Ribosomes
(d) Cytoplasm

(a) Mitochondria

What does the pyruvate kinase enzyme catalyse?
(a) first irreversible step of glycolysis
(b) second irreversible step of glycolysis
(c) third irreversible step of glycolysis
(d) fourth irreversible step of glycolysis

TCA cycle enzymes are located in the mitochondrial matrix except for one that is located in the inner mitochondrial membrane in eukaryotes and in the cytosol in prokaryotes. This enzyme is
(a) Succinate dehydrogenase
(b) Lactate dehydrogenase
(c) Isocitrate dehydrogenase
(d) Malate dehydrogenase

(a) Succinate dehydrogenase

Which of the metabolites is common to the respiration-mediated breakdown of fats, carbohydrates and proteins?
(a) Fructose 1, 6 – bisphosphate
(b) Pyruvic acid
(c) Acetyl CoA
(d) Glucose – 6 – phosphate