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Multiple Choice
Most of the ATP produced during cellular respiration occurs at which step?
A
Electron transport chain and oxidative phosphorylation
B
Citric acid cycle (Krebs cycle)
C
Glycolysis
D
Fermentation
Verified step by step guidance
1
Understand the process of cellular respiration, which consists of three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (electron transport chain).
Recall that ATP is the energy currency of the cell, and its production is a key goal of cellular respiration. Each stage contributes to ATP production, but the amounts vary significantly.
Review glycolysis, which occurs in the cytoplasm. It breaks down glucose into pyruvate, producing a small amount of ATP and NADH. Glycolysis is an anaerobic process and does not require oxygen.
Examine the citric acid cycle (Krebs cycle), which occurs in the mitochondrial matrix. This cycle generates NADH and FADH₂, which are electron carriers, along with a small amount of ATP through substrate-level phosphorylation.
Focus on the electron transport chain and oxidative phosphorylation, which occur in the inner mitochondrial membrane. This is where the majority of ATP is produced. Electrons from NADH and FADH₂ are transferred through protein complexes, creating a proton gradient that drives ATP synthesis via ATP synthase.