Tailed bacteriophages are

Options

A. Motile on surface of bacteria
B. Non-motile
C. Motile on surface of plant leaves
D. Actively motile in water

Answer

### Step-by-Step Solution:

1. **Understanding Tailed Bacteriophages**: Tailed bacteriophages are a type of virus that specifically infects bacteria. They have a distinct structure that includes a head, a collar, a sheath, and a tail.

2. **Structure of Tailed Bacteriophages**:
- **Head**: Contains the genetic material, which is typically DNA.
- **Collar**: Connects the head to the tail.
- **Sheath**: A cylindrical structure that surrounds the tail.
- **Tail**: Composed of tail fibers that help the bacteriophage attach to the bacterial surface.

3. **Motility of Tailed Bacteriophages**: Tailed bacteriophages are generally considered non-motile. They do not move actively like some organisms do. Instead, they rely on their tail fibers to attach to the surface of bacteria.

4. **Attachment Mechanism**: The tail fibers of the bacteriophage have spikes at their ends. These spikes play a crucial role in the attachment process, allowing the bacteriophage to latch onto the bacterial cell surface effectively.

5. **Taxonomy**: Tailed bacteriophages belong to a specific family known as **Cordylovirales**. This family is characterized by certain structural and functional similarities among its members.

6. **Conclusion**: In summary, tailed bacteriophages are non-motile entities that utilize their tail fibers for attachment to bacteria, and they belong to the family Cordylovirales.