oxygen is critical for aerobic respiration. Explain its role with respect to ETS.

Explanation

### Step-by-Step Solution

1. **Understanding Aerobic Respiration**:
- Aerobic respiration is a metabolic process that requires oxygen to produce energy. It occurs in the mitochondria of cells and involves the breakdown of glucose in the presence of oxygen.

2. **Role of Oxygen in Electron Transport System (ETS)**:
- The Electron Transport System (ETS) is the final stage of aerobic respiration. It is responsible for the production of ATP (adenosine triphosphate), the energy currency of the cell.
- In the ETS, oxygen acts as the final electron acceptor. This means that after electrons are passed through a series of proteins in the inner mitochondrial membrane, they ultimately need to be accepted by oxygen.
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