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Multiple Choice
In mitochondrial electron transport, what is the direct role of $\mathrm{O_2}$?
A
It acts as the final electron acceptor, forming water.
B
It pumps protons across the inner mitochondrial membrane.
C
It donates electrons to Complex I.
D
It breaks down glucose into pyruvate.
Verified step by step guidance
1
Understand the context of mitochondrial electron transport: This process occurs in the inner mitochondrial membrane and is part of cellular respiration, where electrons are transferred through a series of protein complexes to generate a proton gradient.
Identify the role of $ ext{O}_2$: Oxygen is involved in the final step of the electron transport chain, where it acts as the terminal electron acceptor. This is crucial for maintaining the flow of electrons through the chain.
Explain the chemical reaction: Oxygen ($ ext{O}_2$) combines with electrons and protons to form water ($ ext{H}_2 ext{O}$). The reaction can be represented as:
Clarify why $ ext{O}_2$ does not perform other roles: Oxygen does not pump protons, donate electrons to Complex I, or break down glucose into pyruvate. These functions are performed by other components of cellular respiration, such as protein complexes and enzymes.
Summarize the importance of $ ext{O}_2$: Without oxygen as the final electron acceptor, the electron transport chain would halt, preventing ATP synthesis and leading to a lack of energy production in aerobic organisms.