NCERT Class 11 Science — Chapter 2: Respiration in Plants

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Which of the following metabolic processes is common to both prokaryotic and eukaryotic cells?

Official previous-year question

Verified 1 Aug 2026.

Options

AElectron transport on the inner mitochondrial membrane
BCitric acid cycle in mitochondria
CCalvin cycle in chloroplasts
DGlycolysis in the cytoplasm

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Solution

The correct option is Glycolysis in the cytoplasm

Explanation

Cellular respiration is the metabolic process by which cells generate energy (ATP) from nutrients. While the fundamental chemical pathways are often similar across life forms, the cellular location of these processes differs between prokaryotes and eukaryotes due to the presence or absence of membrane-bound organelles.

Glycolysis in the cytoplasm is Correct: Glycolysis is the initial step of respiration where glucose is broken down into pyruvate. This process occurs in the cytoplasm (cytosol) of virtually all living cells, including both prokaryotes and eukaryotes. It is an anaerobic process and does not require membrane-bound organelles.
Citric acid cycle in mitochondria is Incorrect: The Citric Acid Cycle (Krebs Cycle) occurs in the matrix of the mitochondria in eukaryotic cells. Since prokaryotic cells lack mitochondria, this cycle occurs in their cytoplasm. Therefore, the location specified in the option is not common to both.
Electron transport on the inner mitochondrial membrane is Incorrect: In eukaryotes, the Electron Transport Chain (ETC) is located on the inner mitochondrial membrane. In prokaryotes, which lack mitochondria, the ETC components are located on the plasma membrane (specifically on infoldings known as mesosomes).
Calvin cycle in chloroplasts is Incorrect: The Calvin cycle is part of photosynthesis, not respiration, and is restricted to photosynthetic organisms (e.g., plants, algae, cyanobacteria). It is not a common metabolic process for all cells. Furthermore, prokaryotes lack chloroplasts; photosynthetic prokaryotes perform these reactions in the cytoplasm or specialized membrane structures.

Key Takeaway: Glycolysis is the universal metabolic pathway common to almost all organisms (prokaryotes and eukaryotes) and always occurs in the cytoplasm.

Your note

More from Chapter 2: Respiration in Plants

Assertion (A): Plants do not present great demands for gas exchange compared to animals. Reason (R): Each plant part takes care of its own gas-exchange needs, resulting in massive transport of gases from one part to another.

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Match the enzyme with its specific action: List I | List II A. Hexokinase | 1. Converts Pyruvate to Acetyl CoA B. Invertase | 2. Reduces Pyruvate to Lactic acid C. Lactate dehydrogenase | 3. Splits Sucrose into Glucose and Fructose D. Pyruvate dehydrogenase | 4. Phosphorylates Glucose Select the correct answer using the code given below

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Assertion (A): Oxygen plays a vital role in the early stages of the Krebs cycle. Reason (R): Oxygen acts as the final hydrogen acceptor in the electron transport system.

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Match the respiratory substrate/enzyme with its entry or action: List I | List II A. Fatty acids | 1. Degrade proteins B. Glycerol | 2. Enter pathway as Acetyl CoA C. Amino acids | 3. Enter pathway as PGAL D. Proteases | 4. Enter at various stages after deamination Select the correct answer using the code given below

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Match the respiration context with its feature: List I | List II A. Yeast | 1. Site of Glycolysis B. Muscle cells (during heavy exercise) | 2. Site of Krebs’ cycle C. Mitochondria | 3. Produces Ethanol and CO₂ D. Cytoplasm | 4. Produces Lactic acid Select the correct answer using the code given below

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The correct option is Glycolysis in the cytoplasm

Explanation

Glycolysis in the cytoplasm is Correct: Glycolysis is the initial step of respiration where glucose is broken down into pyruvate. This process occurs in the cytoplasm (cytosol) of virtually all living cells, including both prokaryotes and eukaryotes. It is an anaerobic process and does not require membrane-bound organelles.
Citric acid cycle in mitochondria is Incorrect: The Citric Acid Cycle (Krebs Cycle) occurs in the matrix of the mitochondria in eukaryotic cells. Since prokaryotic cells lack mitochondria, this cycle occurs in their cytoplasm. Therefore, the location specified in the option is not common to both.
Electron transport on the inner mitochondrial membrane is Incorrect: In eukaryotes, the Electron Transport Chain (ETC) is located on the inner mitochondrial membrane. In prokaryotes, which lack mitochondria, the ETC components are located on the plasma membrane (specifically on infoldings known as mesosomes).
Calvin cycle in chloroplasts is Incorrect: The Calvin cycle is part of photosynthesis, not respiration, and is restricted to photosynthetic organisms (e.g., plants, algae, cyanobacteria). It is not a common metabolic process for all cells. Furthermore, prokaryotes lack chloroplasts; photosynthetic prokaryotes perform these reactions in the cytoplasm or specialized membrane structures.

Key Takeaway: Glycolysis is the universal metabolic pathway common to almost all organisms (prokaryotes and eukaryotes) and always occurs in the cytoplasm.