In the electron transport chain during termined the cytochrome which donates electrons to `0_(1)` is

Options

A. Cytochrome b
B. Cytochrome c
C. Cytochrome `a_(3)`
D. Cytochrome f

Answer

**Step-by-Step Solution:**

1. **Understanding the Electron Transport Chain (ETC):**
The electron transport chain is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions. This process is crucial for cellular respiration and ATP production.

2. **Identifying Key Components:**
In the ETC, various cytochromes play significant roles. Cytochromes are proteins that contain heme groups and are involved in electron transfer. The main cytochromes involved in the electron transport chain include cytochrome b, c, and a.

3. **Focusing on the Final Electron Acceptor:**
The final electron acceptor in the electron transport chain is molecular oxygen (O2). It is reduced to form water (H2O) in the last step of the chain.

4. **Identifying the Cytochrome Donating Electrons to Oxygen:**
The specific cytochrome that donates electrons to oxygen is cytochrome a3. This cytochrome is part of complex IV of the electron transport chain, where the reduction of oxygen occurs.

5. **Conclusion:**
Therefore, the cytochrome that donates electrons to O2 in the electron transport chain is cytochrome a3.

**Final Answer:**
The cytochrome which donates electrons to O2 is cytochrome a3.

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