Proteins present in the natural silk fibre is

Options

A. Fibrin and serine
B. Fibroin and sericin
C. Fibroin and serine
D. Fibroin and elastin

Answer

To answer the question regarding the proteins present in natural silk fiber, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Natural Silk Fiber**:
- Natural silk is primarily obtained from silkworms, specifically the larvae of the Bombyx mori moth.

2. **Identifying the Proteins in Silk**:
- The two main proteins found in natural silk fiber are **Fibroin** and **Sericin**.
- Fibroin is the structural protein that forms the silk thread, while Sericin is a glue-like protein that coats the fibroin fibers.

3. **Evaluating the Options**:
- **Option A**: Fibrin and Serin - Incorrect, as these proteins are not related to silk.
- **Option B**: Fibroin and Sericin - Correct, as both are proteins present in silk.
- **Option C**: Fibroin and Serine - Incorrect, as Serine is an amino acid, not a protein.
- **Option D**: Fibroin and Elastin - Incorrect, as Elastin is not a component of silk.

4. **Conclusion**:
- The correct answer to the question is **Option B: Fibroin and Sericin**.

### Final Answer:
The proteins present in the natural silk fiber are **Fibroin and Sericin**.

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