Respiration in plants MCQ with Answer and Explanation

71. Which of the following statements about the electron transport chain (ETC) is true?

a) The ETC occurs in the cytoplasm
b) Oxygen is the final electron acceptor
c) The ETC occurs in the mitochondria of plant cells only
d) NADH is broken down into glucose in the ETC

Answer: b) Oxygen is the final electron acceptor

Explanation: Oxygen accepts electrons and combines with protons to form water in the electron transport chain, enabling ATP production.

72. Where does the Calvin cycle occur in plant cells?

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

Answer: b) Chloroplasts

Explanation: The Calvin cycle, which is part of photosynthesis, occurs in the stroma of the chloroplasts.

73. In which part of the mitochondrion does the Krebs cycle take place?

a) Outer membrane
b) Intermembrane space
c) Inner membrane
d) Matrix

Answer: d) Matrix

Explanation: The Krebs cycle takes place in the matrix of the mitochondria, where acetyl-CoA is oxidized.

74. What is the main difference between anaerobic and aerobic respiration?

a) Anaerobic respiration produces more ATP
b) Aerobic respiration occurs only in the presence of light
c) Aerobic respiration requires oxygen
d) Anaerobic respiration produces oxygen

Answer: c) Aerobic respiration requires oxygen

Explanation: Aerobic respiration requires oxygen to fully break down glucose and produce a large amount of ATP, while anaerobic respiration does not.

75. Which of the following molecules acts as the final electron acceptor in the electron transport chain?

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

Answer: b) Oxygen

Explanation: Oxygen is the final electron acceptor in the electron transport chain, combining with electrons and hydrogen to form water.

76. Which of the following occurs during both aerobic and anaerobic respiration?

a) Oxygen is consumed
b) Carbon dioxide is produced
c) Glycolysis is performed
d) Lactic acid is produced

Answer: c) Glycolysis is performed

Explanation: Glycolysis occurs in both aerobic and anaerobic respiration, breaking down glucose into pyruvate.

77. In the absence of oxygen, which pathway do plant cells follow for energy production?

a) Glycolysis only
b) Alcoholic fermentation
c) Lactic acid fermentation
d) Both glycolysis and the electron transport chain

Answer: b) Alcoholic fermentation

Explanation: In the absence of oxygen, plant cells undergo alcoholic fermentation, which produces ethanol and carbon dioxide.

78. Which of the following is a characteristic of the electron transport chain?

a) It occurs in the cytoplasm
b) It produces glucose
c) It generates a proton gradient
d) It occurs in the chloroplasts

Answer: c) It generates a proton gradient

Explanation: The electron transport chain generates a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis.

79. How many molecules of ATP are produced in the electron transport chain from one molecule of glucose?

a) 2
b) 38
c) 36
d) 30

Answer: b) 38

Explanation: The complete oxidation of one glucose molecule during aerobic respiration yields a total of 38 ATP molecules.

80. Which of the following is NOT a product of aerobic respiration?

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

Answer: b) Oxygen

Explanation: Oxygen is consumed in aerobic respiration, not produced.