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

The correct Answer is A-3, B-4, C-2, D-1 Explanation Cellular respiration involves a series of metabolic reactions that convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. This process can be aerobic (requiring oxygen) or anaerobic (without oxygen). Different organisms and cellular conditions lead to variations in the end products and sites of these reactions. Statement-wise Analysis 1. A. Yeast - 3. Produces Ethanol and CO₂ - Correct: Yeast performs anaerobic respiration, specifically alcoholic fermentation, in the absence of oxygen. During this process, glucose is broken down into ethanol and carbon dioxide. 2. B. Muscle cells (during heavy exercise) - 4. Produces Lactic acid - Correct: During strenuous physical activity, when oxygen supply to muscle cells is insufficient, they switch to anaerobic respiration (lactic acid fermentation). This process breaks down glucose to produce lactic acid and a small amount of energy. 3. C. Mitochondria - 2. Site of Krebs’ cycle - Correct: The Krebs' cycle (also known as the citric acid cycle) is a key stage of aerobic respiration that occurs in the matrix of the mitochondria. 4. D. Cytoplasm - 1. Site of Glycolysis - Correct: Glycolysis, the initial stage of both aerobic and anaerobic respiration, takes place in the cytoplasm of the cell. During glycolysis, glucose is broken down into pyruvate. Key Takeaway Cellular respiration pathways vary based on oxygen availability and organism type, with glycolysis occurring in the cytoplasm, the Krebs' cycle in mitochondria, and anaerobic processes like alcoholic fermentation (yeast) and lactic acid fermentation (muscle cells) producing distinct end products.

NCERT Class 11 Science — Chapter 2: Respiration in Plants

mcqhard

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

Official previous-year question

Verified 1 Aug 2026.

Options

AA-1, B-2, C-3, D-4
BA-3, B-4, C-2, D-1
CA-4, B-3, C-1, D-2
DA-2, B-1, C-4, D-3

Did you get this right?

Solution

The correct Answer is A-3, B-4, C-2, D-1

Explanation

Cellular respiration involves a series of metabolic reactions that convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. This process can be aerobic (requiring oxygen) or anaerobic (without oxygen). Different organisms and cellular conditions lead to variations in the end products and sites of these reactions.

Statement-wise Analysis

A. Yeast - 3. Produces Ethanol and CO₂
- Correct: Yeast performs anaerobic respiration, specifically alcoholic fermentation, in the absence of oxygen. During this process, glucose is broken down into ethanol and carbon dioxide.
B. Muscle cells (during heavy exercise) - 4. Produces Lactic acid
- Correct: During strenuous physical activity, when oxygen supply to muscle cells is insufficient, they switch to anaerobic respiration (lactic acid fermentation). This process breaks down glucose to produce lactic acid and a small amount of energy.
C. Mitochondria - 2. Site of Krebs’ cycle
- Correct: The Krebs' cycle (also known as the citric acid cycle) is a key stage of aerobic respiration that occurs in the matrix of the mitochondria.
D. Cytoplasm - 1. Site of Glycolysis
- Correct: Glycolysis, the initial stage of both aerobic and anaerobic respiration, takes place in the cytoplasm of the cell. During glycolysis, glucose is broken down into pyruvate.

Key Takeaway

Cellular respiration pathways vary based on oxygen availability and organism type, with glycolysis occurring in the cytoplasm, the Krebs' cycle in mitochondria, and anaerobic processes like alcoholic fermentation (yeast) and lactic acid fermentation (muscle cells) producing distinct end products.

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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With reference to gas exchange in plants, consider the following statements: 1. Individual organs rely entirely on transport from other parts for gaseous needs. 2. Plant metabolism does not demand large-scale convective transport of gases. 3. Intercellular air spaces in parenchyma reduce diffusion distances. 4. In woody stems, living tissues occur in thin layers beneath the bark with openings that aid exchange. Which of the statements given above are correct?

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The correct Answer is A-3, B-4, C-2, D-1

Explanation

Statement-wise Analysis

A. Yeast - 3. Produces Ethanol and CO₂
- Correct: Yeast performs anaerobic respiration, specifically alcoholic fermentation, in the absence of oxygen. During this process, glucose is broken down into ethanol and carbon dioxide.
B. Muscle cells (during heavy exercise) - 4. Produces Lactic acid
- Correct: During strenuous physical activity, when oxygen supply to muscle cells is insufficient, they switch to anaerobic respiration (lactic acid fermentation). This process breaks down glucose to produce lactic acid and a small amount of energy.
C. Mitochondria - 2. Site of Krebs’ cycle
- Correct: The Krebs' cycle (also known as the citric acid cycle) is a key stage of aerobic respiration that occurs in the matrix of the mitochondria.
D. Cytoplasm - 1. Site of Glycolysis
- Correct: Glycolysis, the initial stage of both aerobic and anaerobic respiration, takes place in the cytoplasm of the cell. During glycolysis, glucose is broken down into pyruvate.