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Multiple Choice
During aerobic respiration, molecular oxygen ($\mathrm{O_2}$) is used for which of the following purposes?
A
To break down glucose during glycolysis
B
As the final electron acceptor in the electron transport chain
C
To directly phosphorylate ADP to ATP
D
As a substrate for the citric acid cycle
Verified step by step guidance
1
Understand the process of aerobic respiration: Aerobic respiration is a metabolic pathway that uses oxygen ($\mathrm{O_2}$) to produce energy in the form of ATP. It consists of glycolysis, the citric acid cycle, and the electron transport chain.
Clarify the role of oxygen ($\mathrm{O_2}$): Oxygen is not involved in glycolysis or the citric acid cycle directly. Instead, it plays a critical role in the electron transport chain, which is the final stage of aerobic respiration.
Explain the electron transport chain: In the electron transport chain, electrons are transferred through a series of protein complexes embedded in the inner mitochondrial membrane. This process generates a proton gradient that drives ATP synthesis.
Identify the role of oxygen in the electron transport chain: Oxygen ($\mathrm{O_2}$) acts as the final electron acceptor at the end of the electron transport chain. It combines with electrons and protons to form water ($\mathrm{H_2O}$), ensuring the continuation of the chain.
Eliminate incorrect options: Oxygen does not break down glucose during glycolysis, directly phosphorylate ADP to ATP, or act as a substrate for the citric acid cycle. Its primary role is as the final electron acceptor in the electron transport chain.