A molecule of `FADH_(2)`

Options

A. Consumes one `O_(2)`
B. Consumes one `H_(2)O` molecule
C. Forms 2ATP
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding FADH2**: FADH2 is an important electron carrier in cellular respiration. It is produced during the Krebs cycle when succinate is converted to fumarate. In this reaction, one molecule of FAD (flavin adenine dinucleotide) is reduced to form FADH2.

2. **Role in Electron Transport Chain (ETC)**: FADH2 plays a crucial role in the electron transport chain, where it donates electrons to the chain, which ultimately leads to the production of ATP through oxidative phosphorylation.

3. **Energy Yield from FADH2**: Each molecule of FADH2 can generate approximately 1.5 ATP molecules (or 7.6 kilojoules per mole of energy). This is because FADH2 enters the electron transport chain at a different point compared to NADH, leading to a lower ATP yield.

4. **Analyzing the Options**:
- **Option 1**: "Consumes one oxygen molecule" - This is incorrect. FADH2 itself does not consume oxygen; rather, oxygen is the final electron acceptor in the electron transport chain.
- **Option 2**: "Consumes one water molecule" - This is also incorrect. FADH2 does not consume water.
- **Option 3**: "Forms 2 ATP" - This is the correct answer. FADH2 contributes to the formation of ATP in the electron transport chain.
- **Option 4**: "All of the above" - This is incorrect since options 1 and 2 are false.

5. **Conclusion**: The correct answer is option 3, which states that FADH2 forms 2 ATP molecules during the process of cellular respiration.