A bacteriophage is attached to the receptor site on the host cells:

Explanation

A bacteriophage is a virus that infects bacteria. It attaches to the receptor site on the host cell's cell membrane. The receptor site is a specific molecule on the cell membrane that the bacteriophage can recognize and bind to.Once the bacteriophage has attached to the receptor site, it injects its DNA into the host cell. The DNA then takes over the host cell's machinery and starts to replicate itself. The replicated DNA then produces new bacteriophage particles, which are released from the host cell.