Complete Respiration in Plants Question Bank & Solutions (24 Questions)
Q1 of 24
NEET NCERT Line-by-Line
Cellular respiration is best defined as the:
(A)
Synthesis of glucose using light
(B)
Breaking of C–C bonds by oxidation to release energy
(C)
Exchange of gases through stomata
(D)
Storage of starch in plastids
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Correct Answer: (B) Breaking of C–C bonds by oxidation to release energy
Respiration breaks C–C bonds of complex molecules by oxidation, releasing energy trapped as ATP.
Q2 of 24
NEET NCERT Line-by-Line
Plants carry out gaseous exchange mainly through:
(A)
Lungs and gills
(B)
Stomata and lenticels
(C)
Xylem and phloem
(D)
Root hairs only
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Correct Answer: (B) Stomata and lenticels
Plants lack specialised respiratory organs; they use stomata and lenticels for diffusion.
Q3 of 24
NEET NCERT Line-by-Line
Glycolysis occurs in the:
(A)
Mitochondrial matrix
(B)
Cytoplasm
(C)
Inner mitochondrial membrane
(D)
Chloroplast
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Correct Answer: (B) Cytoplasm
Glycolysis (the EMP pathway) occurs in the cytoplasm of all living cells.
Q4 of 24
NEET NCERT Line-by-Line
The EMP pathway is named after:
(A)
Embden, Meyerhof, Parnas
(B)
Engelmann, Meyer, Priestley
(C)
Emerson, Mehler, Park
(D)
Embden, Mendel, Pasteur
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Correct Answer: (A) Embden, Meyerhof, Parnas
Gustav Embden, Otto Meyerhof and J. Parnas described the scheme of glycolysis.
Q5 of 24
NEET NCERT Line-by-Line
The end product of glycolysis is:
(A)
Acetyl CoA
(B)
Lactic acid
(C)
Pyruvic acid
(D)
Citric acid
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Correct Answer: (C) Pyruvic acid
One glucose → 2 molecules of pyruvic acid (partial oxidation).
Q6 of 24
NEET NCERT Line-by-Line
Net ATP gained in glycolysis per glucose is:
(A)
2
(B)
4
(C)
36
(D)
38
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Correct Answer: (A) 2
4 ATP are produced, 2 are used → net 2 ATP (plus 2 NADH).
Q7 of 24
NEET NCERT Line-by-Line
In alcoholic fermentation, pyruvate is converted to:
(A)
Lactic acid
(B)
CO₂ and ethanol
(C)
Acetyl CoA
(D)
Citric acid
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Correct Answer: (B) CO₂ and ethanol
Pyruvic acid decarboxylase and alcohol dehydrogenase convert pyruvate to CO₂ + ethanol.
Q8 of 24
NEET NCERT Line-by-Line
Lactic acid fermentation is catalysed by:
(A)
Pyruvate dehydrogenase
(B)
Lactate dehydrogenase
(C)
Invertase
(D)
Citrate synthase
Show Answer & NCERT Explanation
Correct Answer: (B) Lactate dehydrogenase
Lactate dehydrogenase reduces pyruvate to lactic acid (e.g. in muscle during low O₂).
Q9 of 24
NEET NCERT Line-by-Line
Yeast die when alcohol concentration reaches about:
(A)
5%
(B)
13%
(C)
25%
(D)
40%
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Correct Answer: (B) 13%
Yeasts poison themselves when alcohol reaches roughly 13%.
Q10 of 24
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Pyruvate is converted to acetyl CoA by the enzyme:
(A)
Hexokinase
(B)
Pyruvate dehydrogenase
(C)
RuBisCO
(D)
ATP synthase
Show Answer & NCERT Explanation
Correct Answer: (B) Pyruvate dehydrogenase
Pyruvate dehydrogenase carries out oxidative decarboxylation: pyruvate + CoA + NAD⁺ → acetyl CoA + CO₂ + NADH.
Q11 of 24
NEET NCERT Line-by-Line
The Krebs cycle takes place in the:
(A)
Cytoplasm
(B)
Mitochondrial matrix
(C)
Inner membrane
(D)
Outer membrane
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Correct Answer: (B) Mitochondrial matrix
The TCA / Krebs cycle operates in the matrix of the mitochondria.
Q12 of 24
NEET NCERT Line-by-Line
The first product of the Krebs cycle is:
(A)
Citric acid
(B)
Succinic acid
(C)
Malic acid
(D)
α-ketoglutaric acid
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Correct Answer: (A) Citric acid
Acetyl CoA + OAA + water → citric acid (catalysed by citrate synthase).
Q13 of 24
NEET NCERT Line-by-Line
Per turn of the Krebs cycle, the number of NADH, FADH₂ and GTP produced is:
(A)
1, 1, 1
(B)
3, 1, 1
(C)
2, 2, 1
(D)
3, 2, 2
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Correct Answer: (B) 3, 1, 1
Each turn: 3 NADH, 1 FADH₂, 1 GTP (and 2 CO₂ released).
Q14 of 24
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Oxidation of one FADH₂ in the ETS yields how many ATP?
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Correct Answer: (B) 2
1 FADH₂ → 2 ATP; 1 NADH → 3 ATP.
Q15 of 24
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The final acceptor of electrons in the ETS is:
(A)
NAD⁺
(B)
FAD
(C)
Oxygen
(D)
Cytochrome c
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Correct Answer: (C) Oxygen
O₂ is the terminal electron/hydrogen acceptor; it is reduced to water.
Q16 of 24
NEET NCERT Line-by-Line
Cytochrome c acts as:
(A)
A complex II carrier
(B)
A mobile carrier between Complex III and IV
(C)
An ATP-synthesising enzyme
(D)
A proton pump in the matrix
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Correct Answer: (B) A mobile carrier between Complex III and IV
Cytochrome c is a small mobile protein carrying electrons between Complex III and Complex IV.
Q17 of 24
NEET NCERT Line-by-Line
In ATP synthase, the proton channel is the:
(A)
F1 component
(B)
F0 component
(C)
Complex I
(D)
Cytochrome c
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Correct Answer: (B) F0 component
F0 is the integral membrane channel; F1 is the headpiece where ATP is made. 2H⁺ pass per ATP.
Q18 of 24
NEET NCERT Line-by-Line
The net theoretical ATP yield from aerobic oxidation of one glucose is:
(A)
2
(B)
12
(C)
36
(D)
38
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Correct Answer: (D) 38
Under the stated assumptions, aerobic respiration nets 38 ATP per glucose.
Q19 of 24
NEET NCERT Line-by-Line
The respiratory pathway is called amphibolic because it:
(A)
Only breaks down molecules
(B)
Involves both catabolism and anabolism
(C)
Occurs in two organelles
(D)
Uses only glucose
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Correct Answer: (B) Involves both catabolism and anabolism
Its intermediates are used in both breakdown (catabolism) and synthesis (anabolism).
Q20 of 24
NEET NCERT Line-by-Line
The respiratory quotient (RQ) for carbohydrates is:
(A)
0.7
(B)
0.9
(C)
1.0
(D)
Greater than 1
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Correct Answer: (C) 1.0
For carbohydrates, equal volumes of CO₂ and O₂ are exchanged, so RQ = 1.
Q21 of 24
NEET NCERT Line-by-Line
The RQ for fats is approximately:
(A)
1.0
(B)
0.9
(C)
0.7
(D)
1.5
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Correct Answer: (C) 0.7
Fats consume more O₂ than the CO₂ they release, so RQ < 1 (≈0.7).
Q22 of 24
NEET NCERT Line-by-Line
Oxidative phosphorylation differs from photophosphorylation because it uses:
(A)
Light energy
(B)
Energy of oxidation-reduction
(C)
Substrate-level energy only
(D)
Heat energy
Show Answer & NCERT Explanation
Correct Answer: (B) Energy of oxidation-reduction
In respiration the proton gradient is built using the energy of redox reactions, not light.
Q23 of 24
NEET NCERT Line-by-Line
Which is true of fermentation?
(A)
Complete oxidation of glucose
(B)
Net 2 ATP per glucose
(C)
Occurs in mitochondria
(D)
Requires oxygen
Show Answer & NCERT Explanation
Correct Answer: (B) Net 2 ATP per glucose
Fermentation only partially breaks down glucose, netting just 2 ATP, anaerobically in the cytoplasm.
Q24 of 24
NEET NCERT Line-by-Line
The link reaction (pyruvate → acetyl CoA) releases, per glucose:
(A)
1 CO₂ and 1 NADH
(B)
2 CO₂ and 2 NADH
(C)
3 CO₂ and 3 NADH
(D)
No CO₂
Show Answer & NCERT Explanation
Correct Answer: (B) 2 CO₂ and 2 NADH
Two pyruvates each release 1 CO₂ + 1 NADH → 2 CO₂ and 2 NADH per glucose.