Respiration in Plants NEET PYQs (2005–2026) with Solutions

10 solved Respiration in Plants PYQs

Real NEET and AIPMT questions from this chapter, newest first. Try each one, then open the answer and the step-by-step explanation.

1. Question 1 (NEET 2026)

   NEET 2026EasyGlycolysis: products per glucose

   How many molecules of pyruvic acid are produced at the end of glycolysis from 206 molecules of glucose?

   1. AOption A: 206
   2. BOption B: 309
   3. COption C: 103
   4. DOption D: 412

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   Correct answer: (D) 412

   Explanation

   In glycolysis, one molecule of glucose (6C) is partially oxidised to two molecules of pyruvic acid (3C each). So for 206 molecules of glucose: $$206 \times 2 = 412 \text{ molecules of pyruvic acid}$$ Hence the answer is option (D).

2. Question 2 (NEET 2026)

   NEET 2026MediumGlycolysis, Krebs Cycle and ETS

   Match List-I with List-II: Choose the correct answer from the options given below:

   1. AOption A: A-IV, B-II, C-I, D-III
   2. BOption B: A-II, B-III, C-IV, D-I
   3. COption C: A-III, B-I, C-IV, D-II
   4. DOption D: A-I, B-IV, C-III, D-II

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   Correct answer: (C) A-III, B-I, C-IV, D-II

   Explanation

   Glycolysis occurs in the cytoplasm, ETS is located on the inner mitochondrial membrane, proton accumulation occurs in the intermembrane space and Krebs cycle takes place in the mitochondrial matrix.

3. Question 3 (NEET 2024)

   NEET 2024MediumAerobic Respiration

   Identify the step in tricarboxylic acid cycle, which does not involve oxidation of substrate.

   1. AOption A: Succinyl-CoA → Succinic acid
   2. BOption B: Isocitrate → α-ketoglutaric acid
   3. COption C: Malic acid → Oxaloacetic acid
   4. DOption D: Succinic acid → Malic acid

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   Correct answer: (A) Succinyl-CoA → Succinic acid

   Explanation

   Conversion of succinyl-CoA to succinic acid is coupled with substrate-level phosphorylation and does not involve oxidation.

4. Question 4 (NEET 2022)

   NEET 2022MediumFermentation

   What amount of energy is released from glucose during lactic acid fermentation?

   1. AOption A: Less than 7%
   2. BOption B: Approximately 15%
   3. COption C: More than 18%
   4. DOption D: About 10%

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   Correct answer: (A) Less than 7%

   Explanation

   Lactic acid fermentation releases only a small fraction of the energy stored in glucose, less than 7%.

5. Question 5 (NEET 2022)

   NEET 2022EasyGlycolysis

   What is the net gain of ATP when each molecule of glucose is converted to two molecules of pyruvic acid?

   1. AOption A: Eight
   2. BOption B: Four
   3. COption C: Six
   4. DOption D: Two

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   Correct answer: (D) Two

   Explanation

   During glycolysis, one glucose molecule is converted into two pyruvate molecules with a net gain of 2 ATP.

6. Question 6 (NEET 2021)

   NEET 2021EasyAerobic Respiration

   Which of the following statements is incorrect?

   1. AOption A: Oxidation-reduction reactions produce proton gradient in respiration
   2. BOption B: During aerobic respiration, role of oxygen is limited to the terminal stage
   3. COption C: In ETC (Electron Transport Chain), one molecule of NADH + $H^+$ gives rise to 2 ATP molecules, and one $FADH_2$ gives rise to 3 ATP molecules
   4. DOption D: ATP is synthesized through Complex V

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   Correct answer: (C) In ETC (Electron Transport Chain), one molecule of NADH + $H^+$ gives rise to 2 ATP molecules, and one $FADH_2$ gives rise to 3 ATP molecules

   Explanation

   Statement (3) is incorrect. In oxidative phosphorylation: - One molecule of NADH + H^+ produces approximately 3 ATP molecules (traditional NCERT value). - One molecule of FADH_2 produces approximately 2 ATP molecules. The statement reverses these values. Statement (1) is correct because electron transport through redox reactions creates a proton gradient. Statement (2) is correct because oxygen acts as the terminal electron acceptor in the final stage of aerobic respiration. Statement (4) is correct because ATP synthase (Complex V) synthesizes ATP.

7. Question 7 (NEET 2020)

   NEET 2020MediumAerobic Respiration

   The number of substrate level phosphorylations in one turn of citric acid cycle is

   1. AOption A: Zero
   2. BOption B: One
   3. COption C: Two
   4. DOption D: Three

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   Correct answer: (B) One

   Explanation

   Only one substrate-level phosphorylation occurs in one turn of the citric acid cycle during the conversion of succinyl-CoA to succinate.

8. Question 8 (NEET 2019)

   NEET 2019EasyAerobic Respiration

   Where is the respiratory electron transport system (ETS) located in plants?

   1. AOption A: Intermembrane space
   2. BOption B: Mitochondrial matrix
   3. COption C: Outer mitochondrial membrane
   4. DOption D: Inner mitochondrial membrane

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   Correct answer: (D) Inner mitochondrial membrane

   Explanation

   The respiratory electron transport system (ETS) in plants is located on the inner mitochondrial membrane where oxidative phosphorylation takes place.

9. Question 9 (NEET 2017)

   NEET 2017HardAerobic Respiration

   Which statement is wrong for Kreb's cycle?

   1. AOption A: The cycle starts with condensation of acetyl group (acetyl CoA) with pyruvic acid to yield citric acid
   2. BOption B: There are three points in the cycle where NAD$^+$ is reduced to NADH + H$^+$
   3. COption C: There is one point in the cycle where FAD$^+$ is reduced to FADH$_2$
   4. DOption D: During conversion of succinyl CoA to succinic acid, a molecule of GTP is synthesised

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   Correct answer: (A) The cycle starts with condensation of acetyl group (acetyl CoA) with pyruvic acid to yield citric acid

   Explanation

   Krebs cycle begins with condensation of acetyl CoA with oxaloacetic acid to form citric acid. Pyruvic acid does not directly participate in this condensation reaction.

10. Question 10 (AIPMT 2012)

    AIPMT 2012HardOxidative Phosphorylation and Nitrogen Fixation

    Read the following four statements (A–D): (A) Both photophosphorylation and oxidative phosphorylation involve uphill transport of protons across the membrane (B) In dicot stems, a new cambium originates from cells of pericycle at the time of secondary growth (C) Stamens in flowers of Gloriosa and Petunia are polyandrous (D) Symbiotic nitrogen-fixers occur in free-living state also in soil. How many of the above statements are right?

    1. AOption A: Three
    2. BOption B: Four
    3. COption C: One
    4. DOption D: Two

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    Correct answer: (D) Two

    Explanation

    Statement (A) is correct because proton transport occurs across membranes during ATP synthesis. Statement (B) is incorrect because interfascicular cambium arises from medullary rays, not pericycle. Statement (C) is incorrect because stamens in Gloriosa and Petunia are epiphyllous, not polyandrous. Statement (D) is correct because Rhizobium can exist freely in soil as well as symbiotically. Thus, two statements are correct. Therefore, option (D) is correct.