Which of the following is the correct sequence of events in cellular respiration? a. glycolysis, citric acid cycle, electron transport chain b. glycolysis, preparatory reaction, citric acid cycle, electron transport chain c. glycolysis, electron transport chain, preparatory reaction d. citric acid cycle, glycolysis, electron transport chain, preparatory reaction e. citric acid cycle, electron transport, glycolysis, preparatory reaction

The correct answer is:

b. glycolysis, preparatory reaction, citric acid cycle, electron transport chain

Explanation:

Cellular respiration occurs in the following sequence:

1. Glycolysis
   • Takes place in the cytoplasm, where glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
2. Preparatory Reaction (Pyruvate Oxidation)
   • Occurs in the mitochondrial matrix, where pyruvate is converted into acetyl-CoA, releasing carbon dioxide and generating NADH.
3. Citric Acid Cycle (Krebs Cycle)
   • Acetyl-CoA enters the cycle, which produces NADH, FADH2_22​, and ATP, while releasing carbon dioxide as a byproduct.
4. Electron Transport Chain
   • NADH and FADH2_22​ donate electrons to the chain in the inner mitochondrial membrane, leading to ATP production through oxidative phosphorylation.