The oxygen consumed during cellular respiration is most directly involved in which of the following processes

The oxygen consumed during cellular respiration is most directly involved in which of the following processes? Glycolysis The oxidation of pyruvate to acetyl CoA Accepting electrons at the end of the electron transport chain The citric acid cycle

The Correct Answer and Explanation is :

The correct answer is: Accepting electrons at the end of the electron transport chain.

Explanation:

Cellular respiration is the process by which cells convert glucose and oxygen into energy, primarily in the form of ATP. The process consists of three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation, which includes the electron transport chain (ETC) and chemiosmosis.

Role of Oxygen:

Oxygen plays a critical role in the final stage of cellular respiration: oxidative phosphorylation, specifically at the end of the electron transport chain. The ETC occurs in the inner mitochondrial membrane, where electrons are transferred through a series of protein complexes (Complex I-IV). These electrons originate from high-energy carriers like NADH and FADH₂, which were produced in earlier stages of cellular respiration.

At the end of the ETC, oxygen serves as the final electron acceptor. It combines with electrons and protons (H⁺ ions) to form water (H₂O). This process is essential for the following reasons:

1. Maintaining the Electron Flow: Without oxygen to accept electrons, the ETC would back up, and the transfer of electrons would cease. This would prevent the generation of the proton gradient necessary for ATP synthesis.
2. ATP Production: The ETC creates a proton gradient across the mitochondrial membrane, driving ATP synthesis through the enzyme ATP synthase. Without oxygen, this gradient cannot be maintained, halting ATP production.

Oxygen is not directly involved in glycolysis, the oxidation of pyruvate, or the citric acid cycle. These processes occur either anaerobically (glycolysis) or before oxygen’s involvement in the ETC. Thus, oxygen’s primary role is as the terminal electron acceptor in the electron transport chain.