Final answer:
Bacteria infected with filamentous phages are known as carrier cells, as they carry the phage and release new phage particles without the cell undergoing lysis.
Step-by-step explanation:
Bacteria that are infected with filamentous phages do not enter a lysogenic cycle where the virus becomes integrated into the bacterial genome as a prophage. Instead, filamentous phages replicate without killing the host cell and are continuously released from the host bacteria. Therefore, infected bacteria with filamentous phages are termed carrier cells, because they carry the phage and release new phage particles, but do not undergo cell lysis and do not form plaques.