Biology
Cellular Respiration and Enzymes
1,551 Questions
Explore key concepts of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain. These questions also cover ATP production, anaerobic respiration, and essential metabolic pathways. This topic forms a core part of the biology syllabus for many competitive examinations.
Glycolysis and metabolic pathwaysKrebs cycle processesElectron transport chainATP production countAnaerobic respiration products
Cellular Respiration and Enzymes Questions
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1 FADH2, 3 NADH2 & 1 ATP
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1 FADH2, 4 NADH2 & 1 ATP
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1 FADH2, 2 NADH2 & 1 ATP
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1 FADH2, 3 NADH2 & 2 ATP
A
Correct answer
Explanation
In one turn of the Krebs cycle, the oxidation of acetyl-CoA produces 3 NADH, 1 FADH2, and 1 ATP (or GTP).
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38 ATP molecules
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2 ATP molecules
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8 ATP molecules
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30 ATP molecules
A
Correct answer
Explanation
Under ideal conditions in eukaryotic cells, the complete aerobic respiration of one molecule of glucose yields a net gain of 36 to 38 ATP molecules depending on the shuttle system used.
A
Correct answer
Explanation
The Electron Transport System (ETS) is the process that drives oxidative phosphorylation, where ATP is synthesized using the energy released from electron transport.
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2 and 3
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3 and 3
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3 and 2
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3 and 4
C
Correct answer
Explanation
The oxidation of one molecule of NADH yields approximately 3 ATP, while the oxidation of one molecule of FADH2 yields approximately 2 ATP due to the entry point into the electron transport chain.
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NADH dehydrigenase is complex I
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FADH2 is Complex II
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Cytochrome bC1 is Complex III and Cytochrome c oxidase is comeplx IV
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All
D
Correct answer
Explanation
Complex I is NADH dehydrogenase, Complex II is Succinate dehydrogenase (FADH2), Complex III is Cytochrome bc1, and Complex IV is Cytochrome c oxidase. All statements are correct.
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TCA Cycle
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Citric Acid Cycle
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Both
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None
C
Correct answer
Explanation
The Krebs cycle is commonly referred to as both the TCA (Tricarboxylic Acid) Cycle and the Citric Acid Cycle.
A
Correct answer
Explanation
Pyruvic acid undergoes oxidative decarboxylation by the pyruvate dehydrogenase complex to form Acetyl-CoA, NADH, and CO2.
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Pathways of Anaerobic respiration
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Pathways of Aerobic respiration
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Both
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None
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Glycolysis occurs in Cytoplasm
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Krebs cycle occurs in Mitochondria
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ETS occurs on the inner membrane of the mitochondria
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All
D
Correct answer
Explanation
Glycolysis occurs in the cytoplasm, the Krebs cycle occurs in the mitochondrial matrix, and the ETS occurs on the inner mitochondrial membrane. All statements are correct.
A
Correct answer
Explanation
During anaerobic respiration (fermentation), only the 2 ATP produced during glycolysis are generated, as there is no oxidative phosphorylation.
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Lactic acid
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Ethyl alcohol
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Both
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None
C
Correct answer
Explanation
During anaerobic respiration, pyruvic acid undergoes fermentation. Depending on the organism, it can be converted into lactic acid (in muscles or bacteria) or ethyl alcohol (in yeast).
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2 and 8
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2 and 6
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8 and 2
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2 and 2
C
Correct answer
Explanation
In glycolysis, 4 ATP are produced via substrate-level phosphorylation, but 2 ATP are consumed in the preparatory phase, resulting in a net gain of 2 ATP. The total of 8 ATP often refers to the total yield including NADH oxidation in aerobic conditions, but the question phrasing is slightly ambiguous regarding the 'total' vs 'net' distinction.
C
Correct answer
Explanation
Glycolysis, also known as the Embden-Meyerhof-Parnas pathway, consists of a specific sequence of 10 enzyme-catalyzed reactions that convert glucose into pyruvate.
A
Correct answer
Explanation
The statement is a placeholder or context-dependent question. Assuming it refers to the general concept of glycolysis, it is true.