Class 11 Biology MCQ – Respiration in Plants

1. Which of the following processes releases energy in plants?

a) Photosynthesis
b) Transpiration
c) Respiration
d) Diffusion

Answer:

c) Respiration

Explanation:

Respiration is the metabolic process in which stored energy is released, providing the necessary energy for cellular activities.

2. Where does glycolysis occur in plant cells?

a) Chloroplast
b) Mitochondria
c) Cytoplasm
d) Nucleus

Answer:

c) Cytoplasm

Explanation:

Glycolysis, the initial step in the breakdown of glucose, occurs in the cytoplasm.

3. Which of the following is a product of glycolysis?

a) Glucose
b) Oxygen
c) Pyruvate
d) ATP

Answer:

c) Pyruvate

Explanation:

Glycolysis breaks down glucose, producing pyruvate as one of its products.

4. In the absence of oxygen, pyruvate is converted to:

a) Alcohol
b) Lactic acid
c) Acetyl CoA
d) Citric acid

Answer:

a) Alcohol

Explanation:

In anaerobic conditions, pyruvate undergoes fermentation to produce alcohol in plants.

5. The Krebs cycle takes place in:

a) Cytoplasm
b) Mitochondrial matrix
c) Chloroplast
d) Ribosome

Answer:

b) Mitochondrial matrix

Explanation:

The Krebs cycle, also known as the citric acid cycle, occurs in the mitochondrial matrix.

6. During respiration, which of the following gases is released?

a) Oxygen
b) Carbon dioxide
c) Nitrogen
d) Hydrogen

Answer:

b) Carbon dioxide

Explanation:

Respiration results in the breakdown of glucose, leading to the release of carbon dioxide.

7. Which molecule acts as the final electron acceptor in aerobic respiration?

a) Glucose
b) ATP
c) Oxygen
d) Carbon dioxide

Answer:

c) Oxygen

Explanation:

In aerobic respiration, oxygen acts as the final electron acceptor, forming water.

8. Which of the following processes does not produce ATP?

a) Glycolysis
b) Electron transport chain
c) Krebs cycle
d) Fermentation

Answer:

d) Fermentation

Explanation:

Fermentation regenerates NAD+ but does not produce ATP.

9. The breakdown of one glucose molecule in aerobic respiration releases how many ATP molecules?

a) 2
b) 8
c) 32
d) 38

Answer:

d) 38

Explanation:

Through glycolysis, the Krebs cycle, and the electron transport chain, a total of up to 38 ATP molecules can be produced from one glucose molecule.

10. The process of converting glucose into ethanol and carbon dioxide in plants is known as:

a) Glycolysis
b) Krebs cycle
c) Lactic acid fermentation
d) Alcoholic fermentation

Answer:

d) Alcoholic fermentation

Explanation:

In the absence of oxygen, plants convert glucose into ethanol and carbon dioxide through alcoholic fermentation.

11. RQ (Respiratory Quotient) for carbohydrates is typically:

a) 0.5
b) 1
c) 1.5
d) 2

Answer:

b) 1

Explanation:

The Respiratory Quotient (RQ) for carbohydrates is 1, indicating that the amount of CO2 produced is equal to the amount of O2 consumed.

12. In which process is NADH produced?

a) Electron transport chain
b) Krebs cycle
c) Fermentation
d) Glycolysis

Answer:

d) Glycolysis

Explanation:

NADH is produced during glycolysis when glucose is broken down.

13. The electron transport chain is located in the:

a) Cytoplasm
b) Chloroplast
c) Nucleus
d) Mitochondrial inner membrane

Answer:

d) Mitochondrial inner membrane

Explanation:

The electron transport chain is situated in the inner membrane of the mitochondria.

14. Which of the following is not a product of the Krebs cycle?

a) ATP
b) NADH
c) FADH2
d) Glucose

Answer:

d) Glucose

Explanation:

The Krebs cycle produces ATP, NADH, and FADH2 but not glucose.

15. In plants, the primary purpose of respiration is to:

a) Produce glucose
b) Produce oxygen
c) Release energy from glucose
d) Absorb sunlight

Answer:

c) Release energy from glucose

Explanation:

The primary purpose of respiration in plants is to release energy stored in glucose to be used for various cellular activities.

16. Cyanide affects which part of respiration?

a) Glycolysis
b) Krebs cycle
c) Alcoholic fermentation
d) Electron transport chain

Answer:

d) Electron transport chain

Explanation:

Cyanide inhibits the electron transport chain by binding to cytochrome c oxidase.

17. Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA?

a) Hexokinase
b) Pyruvate kinase
c) Pyruvate dehydrogenase
d) Citrate synthase

Answer:

c) Pyruvate dehydrogenase

Explanation:

The conversion of pyruvate to acetyl-CoA is catalyzed by pyruvate dehydrogenase.

18. In anaerobic respiration, the number of ATP molecules produced is:

a) Less than aerobic respiration
b) More than aerobic respiration
c) Equal to aerobic respiration
d) None

Answer:

a) Less than aerobic respiration

Explanation:

Anaerobic respiration is less efficient than aerobic respiration and produces fewer ATP molecules.

19. Which process produces the most NADH molecules during respiration?

a) Glycolysis
b) Krebs cycle
c) Fermentation
d) Electron transport chain

Answer:

b) Krebs cycle

Explanation:

The Krebs cycle produces three NADH molecules for each turn, making it the largest producer of NADH during respiration.

20. In which part of the plant cell does anaerobic respiration primarily occur?

a) Mitochondria
b) Cytoplasm
c) Chloroplast
d) Vacuole

Answer:

b) Cytoplasm

Explanation:

Anaerobic respiration, or fermentation, primarily takes place in the cytoplasm of the cell.

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