The ultimate electron acceptor of respiration in an aerobic organism is

Options

A. cytochrome
B. oxygen
C. hydrogen
D. glucose

Explanation

**Step-by-Step Solution:**

1. **Understanding Aerobic Respiration**: Aerobic respiration occurs in the presence of oxygen. It is a process by which organisms convert glucose and oxygen into energy, carbon dioxide, and water.

2. **Identifying Electron Acceptors**: In the context of respiration, an electron acceptor is a molecule that receives electrons during the process of cellular respiration.

3. **Role of the Electron Transport Chain**: The electron transport chain (ETC) is a series of complexes located in the inner mitochondrial membrane. It is responsible for transferring electrons from electron donors like NADH and FADH2 to the final electron acceptor.

4. **Electron Donors**: During aerobic respiration, NADH and FADH2 are generated from earlier stages of respiration (like glycolysis and the Krebs cycle). These molecules donate electrons to the electron transport chain.

5. **Final Electron Acceptor**: In aerobic organisms, the ultimate electron acceptor in the electron transport chain is oxygen. Oxygen combines with electrons and hydrogen ions to form water.

6. **Conclusion**: Therefore, the ultimate electron acceptor of respiration in an aerobic organism is oxygen.

**Final Answer**: The ultimate electron acceptor of respiration in an aerobic organism is oxygen.

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