Which stage of aerobic cellular respiration occurs in the cytoplasm?

• A. Krebs cycle
• B. Oxidative phosphorylation
• C. Glycolysis
• D. Formation of acetyl CoA

Answer: (C)

The correct answer is glycolysis, as this is the stage of aerobic cellular respiration that occurs in the cytoplasm of the cell. During glycolysis, glucose is broken down into two molecules of pyruvate, generating a small amount of ATP and NADH in the process. This initial step does not require oxygen and serves as the preparatory phase for further energy extraction.

Understanding where each phase of cellular respiration takes place is essential for grasping cellular metabolism. The Krebs cycle occurs in the mitochondrial matrix, where it processes acetyl CoA to produce electron carriers for the next stage. Oxidative phosphorylation takes place in the inner mitochondrial membrane, where the electron transport chain and ATP synthase function to utilize the electrons derived from NADH and FADH2 to generate a significant amount of ATP. The formation of acetyl CoA occurs in the mitochondria and is a crucial link between glycolysis and the Krebs cycle.

Recognizing that glycolysis is unique among these processes because it happens outside the mitochondria in the cytoplasm helps clarify its fundamental role in energy production and metabolic pathways.