How would the electron transport chain be affected if oxygen was not present in the cell?

• A. The electron transport chain would switch to using carbon dioxide instead of oxygen.
• B. The electron transport chain would produce more ATP than usual.
• C. The electron transport chain would halt, preventing ATP production.
• D. The electron transport chain would continue to function normally.

Answer: (C)

Verified step by step guidance

1. Understand the role of oxygen in the electron transport chain: Oxygen acts as the final electron acceptor in the electron transport chain, which is a crucial step in cellular respiration.
2. Recognize the consequences of oxygen absence: Without oxygen, the electron transport chain cannot complete its function, as electrons have no terminal acceptor.
3. Consider the impact on ATP production: The electron transport chain is responsible for creating a proton gradient that drives ATP synthesis. Without oxygen, this process is disrupted, halting ATP production.
4. Explore alternative pathways: In the absence of oxygen, cells may resort to anaerobic respiration or fermentation to generate ATP, albeit less efficiently.
5. Conclude the effect on cellular respiration: The absence of oxygen leads to a cessation of the electron transport chain, significantly impacting the cell's energy production capabilities.