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Multiple Choice
In cellular respiration, the most energy is transferred during which stage?
A
Electron transport chain
B
Glycolysis
C
Fermentation
D
Krebs cycle (citric acid cycle)
Verified step by step guidance
1
Step 1: Begin by understanding the process of cellular respiration, which is the metabolic pathway that cells use to convert glucose into energy (ATP). It consists of several stages: glycolysis, the Krebs cycle (citric acid cycle), and the electron transport chain.
Step 2: Review the role of glycolysis. Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP and NADH. This stage transfers some energy but not the most.
Step 3: Examine the Krebs cycle (citric acid cycle). This cycle occurs in the mitochondria and generates electron carriers (NADH and FADH2) by oxidizing acetyl-CoA. It produces ATP, but its primary role is to supply high-energy electrons for the next stage.
Step 4: Consider the electron transport chain (ETC). The ETC is located in the inner mitochondrial membrane and uses electrons from NADH and FADH2 to create a proton gradient. This gradient drives ATP synthesis through oxidative phosphorylation, transferring the most energy in cellular respiration.
Step 5: Eliminate fermentation as an option. Fermentation is an anaerobic process that occurs when oxygen is unavailable, producing minimal ATP compared to the other stages. Based on this analysis, the electron transport chain is the stage where the most energy is transferred.