Question

During the process of aerobic respiration, O\(_2\) utilisation occurs in the following stage only:

• A. Glycolysis
• B. Glycolysis and Krebs cycle
• C. Krebs cycle and ETS
• D. ETS (Electron Transport System)

Hint:

Oxygen is used at the final step of aerobic respiration, where it serves as the final electron acceptor in the Electron Transport System, forming water.

Answer 1

The Correct Option is D

In aerobic respiration, oxygen is primarily used during the Electron Transport System (ETS). The ETS is the final stage of cellular respiration, occurring in the inner mitochondrial membrane, where oxygen is the final electron acceptor, forming water. Oxygen is not directly used in earlier stages of cellular respiration like glycolysis and the Krebs cycle. Here’s a breakdown of the options:
- Glycolysis: This process does not require oxygen and occurs in the cytoplasm, producing pyruvate without any oxygen consumption.
- Glycolysis and Krebs cycle: Although the Krebs cycle requires oxygen indirectly (since it regenerates NAD\(^+\) and FAD\(^+\) in an oxygen-dependent manner), oxygen itself is not directly consumed until the ETS.
- Krebs cycle and ETS: The Krebs cycle itself does not use oxygen directly, but oxygen is required in the ETS to accept electrons and produce water.
- ETS (Electron Transport System): This is where oxygen is directly used in the process of accepting electrons to form water. Thus, the correct answer is ETS (Electron Transport System), where oxygen is directly utilised.