The primary food plant of silk worm is _________________.

Answer

**Step-by-Step Text Solution:**

1. **Identify the Organism**: The question asks about the primary food plant of silkworms. Silkworms are the larvae of the silk moth, primarily known for their role in silk production.

2. **Research the Diet of Silkworms**: Silkworms primarily feed on the leaves of specific plants. It's essential to identify which plant is their primary source of food.

3. **Determine the Primary Food Plant**: After researching, it is found that the primary food plant of silkworms is the castor plant. Silkworms consume the leaves of the castor plant to obtain the necessary nutrients for their growth and development.

4. **Explain the Importance of the Food Plant**: The leaves of the castor plant are crucial for the silkworms as they provide the energy and nutrients needed for their life cycle. Silkworms use the nutrients from the castor leaves to produce silk through their saliva, which is secreted during the cocoon-making process.

5. **Conclusion**: Therefore, the primary food plant of silkworms is the castor plant.

**Final Answer**: The primary food plant of silkworm is **castor plant**.

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