Top 50 MCQ on Plant Respiration ( Glycolysis, Krebs cycle and ETS pathway)
Which process occurs in the cytoplasm and breaks down glucose into pyruvate?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: a) Glycolysis
What is the net production of ATP molecules during glycolysis?
a) 1 ATP
b) 2 ATP
c) 4 ATP
d) 8 ATP
Answer: b) 8 ATP
In glycolysis, one molecule of glucose is converted into how many molecules of pyruvate?
a) 1
b) 2
c) 3
d) 4
Answer: b) 2
Which molecule is the final electron acceptor in the electron transport system?
a) Oxygen
b) Pyruvate
c) NADH
d) FADH2
Answer: a) Oxygen
Where does the Krebs cycle occur in eukaryotic cells?
a) Cytoplasm
b) Nucleus
c) Mitochondria
d) Endoplasmic reticulum
Answer: c) Mitochondria
How many ATP molecules are produced from one molecule of glucose through oxidative phosphorylation?
a) 2 ATP
b) 4 ATP
c) 28 ATP
d) 38 ATP
Answer: d) 38 ATP
What is the respiratory quotient (RQ) defined as?
a) The ratio of carbon dioxide produced to oxygen consumed during respiration
b) The ratio of oxygen produced to carbon dioxide consumed during respiration
c) The ratio of glucose produced to pyruvate consumed during respiration
d) The ratio of pyruvate produced to glucose consumed during respiration
Answer: a) The ratio of carbon dioxide produced to oxygen consumed during respiration
Which of the following factors does NOT affect the rate of respiration?
a) Temperature
b) pH
c) Concentration of enzymes
d) Atmospheric pressure
Answer: d) Atmospheric pressure
What happens to the respiratory quotient (RQ) when carbohydrates are the main source of fuel?
a) RQ decreases
b) RQ increases
c) RQ remains constant
d) RQ becomes negative
Answer: b) RQ increases
Which molecule carries high-energy electrons to the electron transport system?
a) NADH
b) FADH2
c) ATP
d) Pyruvate
Answer: a) NADH
How many ATP molecules are produced from one NADH molecule during oxidative phosphorylation?
a) 1 ATP
b) 2 ATP
c) 3 ATP
d) 4 ATP
Answer: b) 3 ATP
Which step in cellular respiration produces the majority of ATP molecules?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: d) Oxidative phosphorylation
In which phase of respiration is carbon dioxide primarily produced?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: b) Krebs cycle
What is the purpose of the Krebs cycle in cellular respiration?
a) Production of ATP
b) Production of NADH and FADH2
c) Conversion of pyruvate into acetyl-CoA
d) Oxidation of glucose
Answer: b) Production of NADH and FADH2
Which molecule is the starting substrate for the Krebs cycle?
a) Pyruvate
b) Acetyl-CoA
c) Citrate
d) Oxaloacetate
Answer: b) Acetyl-CoA
Which of the following is NOT a product of the Krebs cycle?
a) ATP
b) NADH
c) FADH2
d) Carbon dioxide
Answer: a) ATP
What is the final product of glycolysis?
a) Pyruvate
b) Acetyl-CoA
c) ATP
d) Carbon dioxide
Answer: a) Pyruvate
How many NADH molecules are produced during glycolysis?
a) 1 NADH
b) 2 NADH
c) 3 NADH
d) 4 NADH
Answer: b) 2 NADH
Which of the following is NOT a step of glycolysis?
a) Energy investment phase
b) Cleavage phase
c) Energy payoff phase
d) Decarboxylation phase
Answer: d) Decarboxylation phase
What is the function of the electron transport system in cellular respiration?
a) Production of ATP
b) Production of pyruvate
c) Oxidation of glucose
d) Conversion of NADH to NAD+
Answer: a) Production of ATP
What is the role of oxygen in the electron transport system?
a) Oxygen is the final electron acceptor, forming water
b) Oxygen is converted into carbon dioxide
c) Oxygen is used to produce ATP directly
d) Oxygen acts as a coenzyme in the reactions
Answer: a) Oxygen is the final electron acceptor, forming water
What is the main function of the electron transport system in cellular respiration?
a) To generate ATP by oxidative phosphorylation
b) To convert pyruvate into acetyl-CoA
c) To produce NADH and FADH2
d) To break down glucose into pyruvate
Answer: a) To generate ATP by oxidative phosphorylation
What is the role of ATP synthase in the electron transport system?
a) To transport electrons between the protein complexes
b) To convert ADP into ATP using the energy from the proton gradient
c) To catalyze the oxidation of NADH and FADH2
d) To release carbon dioxide as a byproduct
Answer: b) To convert ADP into ATP using the energy from the proton gradient
Which of the following is an anaerobic process?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: a) Glycolysis
What is the respiratory quotient (RQ) for fats as the primary fuel source?
a) RQ < 0.7
b) RQ = 0.7
c) RQ > 0.7
d) RQ = 1.0
Answer: c) RQ > 0.7
Which factor does NOT affect the rate of respiration?
a) Temperature
b) pH
c) Enzyme concentration
d) Atmospheric pressure
Answer: d) Atmospheric pressure
What happens to respiration rate with an increase in temperature?
a) Respiration rate increases
b) Respiration rate decreases
c) Respiration rate remains the same
d) Respiration rate becomes unpredictable
Answer: a) Respiration rate increases
How does pH affect the rate of respiration?
a) High pH increases respiration rate
b) Low pH increases respiration rate
c) High pH decreases respiration rate
d) Low pH decreases respiration rate
Answer: c) High pH decreases respiration rate
Which of the following is NOT a factor affecting respiration?
a) Concentration of substrate
b) Availability of oxygen
c) Age of the organism
d) Presence of inhibitors
Answer: c) Age of the organism
What is the primary substrate used for respiration in most organisms?
a) Glucose
b) Lipids
c) Proteins
d) Nucleic acids
Answer: a) Glucose
How does the concentration of enzymes affect respiration?
a) Higher enzyme concentration increases respiration rate
b) Lower enzyme concentration increases respiration rate
c) Higher enzyme concentration decreases respiration rate
d) Lower enzyme concentration decreases respiration rate
Answer: a) Higher enzyme concentration increases respiration rate
Which of the following is a product of the Krebs cycle?
a) NADH
b) FADH2
c) ATP
d) Carbon dioxide
Answer: d) Carbon dioxide
Where does glycolysis occur?
a) Cytoplasm
b) Mitochondria
c) Nucleus
d) Endoplasmic reticulum
Answer: a) Cytoplasm
Which step in cellular respiration generates the most ATP molecules?
a) Electron transport system
b) Glycolysis
c) Krebs cycle
d) Oxidative phosphorylation
Answer: d) Oxidative phosphorylation
What is the purpose of the electron transport system in cellular respiration?
a) To produce NADH and FADH2
b) To convert pyruvate into acetyl-CoA
c) To generate ATP by oxidative phosphorylation
d) To break down glucose into pyruvate
Answer: c) To generate ATP by oxidative phosphorylation
Which molecule is the final electron acceptor in the electron transport system?
a) Oxygen
b) Carbon dioxide
c) NADH
d) FADH2
Answer: a) Oxygen
What is the role of ATP synthase in cellular respiration?
a) To transport electrons between the protein complexes
b) To convert ADP into ATP using the energy from the proton gradient
c) To catalyze the oxidation of NADH and FADH2
d) To release carbon dioxide as a byproduct
Answer: b) To convert ADP into ATP using the energy from the proton gradient
What is the net production of ATP molecules in glycolysis?
a) 1 ATP
b) 2 ATP
c) 4 ATP
d) 8 ATP
Answer: b) 8 ATP
Which molecule carries high-energy electrons to the electron transport system?
a) NADH
b) FADH2
c) ATP
d) Pyruvate
Answer: a) NADH
What is the primary function of the Krebs cycle in cellular respiration?
a) Production of ATP
b) Production of NADH and FADH2
c) Conversion of pyruvate into acetyl-CoA
d) Oxidation of glucose
Answer: b) Production of NADH and FADH2
In which phase of respiration is carbon dioxide primarily produced?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: b) Krebs cycle
What is the function of oxygen in respiration?
a) To produce energy directly
b) To convert glucose into pyruvate
c) To act as the final electron acceptor in the electron transport system
d) To convert carbon dioxide into oxygen
Answer: c) To act as the final electron acceptor in the electron transport system
Which process produces the most ATP molecules in cellular respiration?
a) Glycolysis
b) Krebs cycle
c) Electron transport system
d) Oxidative phosphorylation
Answer: d) Oxidative phosphorylation
What is the respiratory quotient (RQ) for carbohydrates as the primary fuel source?
a) RQ < 0.7
b) RQ = 0.7
c) RQ > 0.7
d) RQ = 1.0
Answer: b) RQ = 0.7
How does temperature affect the rate of respiration?
a) Higher temperature increases respiration rate
b) Lower temperature increases respiration rate
c) Higher temperature decreases respiration rate
d) Lower temperature decreases respiration rate
Answer: a) Higher temperature increases respiration rate
What is the role of pH in respiration?
a) High pH increases respiration rate
b) Low pH increases respiration rate
c) High pH decreases respiration rate
d) Low pH decreases respiration rate
Answer: c) High pH decreases respiration rate
What is the primary factor affecting respiration rate?
a) Availability of oxygen
b) Concentration of enzymes
c) Temperature
d) pH
Answer: a) Availability of oxygen
What is the effect of substrate concentration on respiration rate?
a) Higher substrate concentration increases respiration rate
b) Lower substrate concentration increases respiration rate
c) Higher substrate concentration decreases respiration rate
d) Lower substrate concentration decreases respiration rate
Answer: a) Higher substrate concentration increases respiration rate
Which of the following is NOT a factor affecting respiration rate?
a) Concentration of enzymes
b) pH
c) Size of the organism
d) Presence of inhibitors
Answer: c) Size of the organism
What is the primary substrate used for respiration in most organisms?
a) Glucose
b) Lipids
c) Proteins
d) Nucleic acids
Answer: a) Glucose
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