The motile bacteria are also to move by

Options

A. pili
B. fimbriae
C. flagella
D. cilia

Answer

**Step-by-Step Solution:**

1. **Understanding Motility in Bacteria**:
- Motility is crucial for bacteria as it allows them to move towards nutrients or away from harmful substances.

2. **Identifying the Options**:
- The options provided are pili, fimbri, flagella, and cilia.

3. **Analyzing Pili and Fimbri**:
- Pili are long, hair-like structures that help bacteria adhere to surfaces. They are not primarily involved in movement.
- Fimbri are shorter and stiffer than pili and also assist in adherence, not motility.

4. **Analyzing Flagella and Cilia**:
- Flagella are long, whip-like structures that enable bacteria to swim and are essential for their locomotion.
- Cilia are shorter and help in moving fluids and materials but are not primarily responsible for bacterial movement.

5. **Conclusion**:
- The structure that allows motile bacteria to move is **flagella**.

**Final Answer**: Motile bacteria move by **flagella**.

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