Which one of the following is the terminal electron acceptor?

Options

A. Molecular `CO_(2)`
B. Molecular `O_(2)`
C. Molecular `H_(2)`
D. `NADPH_(2)`

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the terminal electron acceptor in a biological process. In the context of cellular respiration, particularly during the electron transport chain (ETC), we need to identify which molecule acts as the final acceptor of electrons.

2. **Identifying the Process**: The electron transport chain is a series of complexes that facilitate the transfer of electrons derived from NADH and FADH2. These electrons are passed through various protein complexes in the inner mitochondrial membrane.

3. **Role of Electron Carriers**: NADH and FADH2 donate electrons to the electron transport chain. As these electrons move through the chain, they lose energy, which is used to pump protons across the membrane, creating a proton gradient.

4. **Final Electron Acceptors**: The final step in the electron transport chain involves the transfer of electrons to a terminal electron acceptor. In aerobic respiration, this acceptor is molecular oxygen (O2).

5. **Formation of Water**: When oxygen accepts electrons, it combines with protons (H+) to form water (H2O). This reaction is crucial for maintaining the flow of electrons through the chain and for the overall process of cellular respiration.

6. **Conclusion**: Based on the above understanding, the terminal electron acceptor in the electron transport chain is molecular oxygen (O2).

**Final Answer**: The terminal electron acceptor is molecular oxygen (O2).

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