Which metabolic pathway breaks down one molecule of glucose into two molecules of pyruvate in the cytoplasm?
Correct answer: C. Glycolysis
- A. Oxidation of pyruvate
- B. Citric acid cycle
- C. Glycolysis
- D. Oxidative phosphorylation
Explanation
Glycolysis is the first stage of cellular respiration that takes place in the cytoplasm. It is anaerobic and produces pyruvate, which can follow different pathways based on the presence of oxygen. If oxygen is available, pyruvate undergoes oxidation and enters the citric acid cycle. Without oxygen, it may undergo fermentation. Thus, glycolysis is the step after which cellular respiration varies based on the conditions. The other options-oxidation of pyruvate, citric acid cycle, and oxidative phosphorylation-are steps that follow glycolysis and depend on oxygen availability, making glycolysis the correct answer.
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About Bioenergetics
Cellular respiration explains how cells release energy from glucose through glycolysis, the link reaction, Krebs cycle and electron transport chain. It includes ATP production, substrate-level and oxidative phosphorylation, aerobic versus anaerobic respiration, and the roles of mitochondria, oxygen and fermentation in energy transfer.
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