Root nodules are founds in

Options

A. Some leguminous plants only
B. In all plants
C. Some leguminous plants and some other plants also
D. All leguminous plants but never in other plants.

Answer

**Step-by-Step Solution:**

1. **Understanding Root Nodules**: Root nodules are specialized structures that form on the roots of certain plants. They are primarily associated with the process of nitrogen fixation.

2. **Identifying the Plants**: Root nodules are most commonly found in leguminous plants, which belong to the family Fabaceae. These plants have a symbiotic relationship with nitrogen-fixing bacteria.

3. **Role of Nitrogen-Fixing Bacteria**: The bacteria, primarily of the genus Rhizobium, invade the root hairs of leguminous plants. This invasion leads to the formation of root nodules where nitrogen fixation occurs.

4. **Nitrogen Fixation Process**: Within the root nodules, the bacteria convert atmospheric nitrogen into a form that the plant can use for growth. This process is essential for the plant's nutrition.

5. **Presence of Leghemoglobin**: Root nodules contain a red pigment called leghemoglobin, which helps in the transport of oxygen to the bacteria while protecting them from the oxygen that could be harmful to their nitrogen-fixing activity.

6. **Analyzing the Options**:
- **Option A**: Some leguminous plants only - This is partially correct but does not include other plants.
- **Option B**: In all plants - This is incorrect as root nodules are not found in all plants.
- **Option C**: Some leguminous plants and some other plants also - This is correct as root nodules can be found in some other non-leguminous plants as well.
- **Option D**: All leguminous plants but never in other plants - This is incorrect because root nodules can also be found in some other plants.

7. **Conclusion**: Based on the analysis, the correct answer is **Option C: Some leguminous plants and some other plants also**.

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