Bacteria can prepare food from

Options

A. `NO_(3)`
B. `N_(2)`
C. `O_(2)`
D. Glycogen.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks what substance bacteria can use to prepare food. We have four options to consider: NO3 (nitrate), N2 (nitrogen gas), O2 (oxygen), and Glycogen.

2. **Analyzing the Options**:
- **NO3 (Nitrate)**: While bacteria can utilize nitrates for nitrogen fixation, it is not a direct source for food preparation.
- **N2 (Nitrogen gas)**: Bacteria can fix nitrogen from the atmosphere, but again, nitrogen gas itself is not a food source.
- **O2 (Oxygen)**: Oxygen is essential for respiration in aerobic bacteria but is not a food source.
- **Glycogen**: Glycogen is a polysaccharide that serves as a form of energy storage in bacteria. It is a polymer of glucose and can be metabolized by bacteria to produce energy.

3. **Identifying the Correct Option**: Among the options, glycogen is the only substance that bacteria can directly use to prepare food. It is a carbohydrate that can be easily metabolized by bacteria.

4. **Conclusion**: Therefore, the correct answer is that bacteria can prepare food from **Glycogen**.

**Final Answer**: Glycogen (Option 4).

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