Final answer:
Motile bacteria use long, thin cellular appendages called flagella to move. Flagella act like propellers and can be located variably on the bacterial cell. Cilia are not found on bacteria and pili are used for other functions, not motility.
Step-by-step explanation:
Motile bacteria usually have one or more long, thin cellular appendages called flagella. Flagella are structures used by cells to move in aqueous environments. They act like propellers, being stiff spiral filaments that extend outward from the cell and spin, propelling the bacteria forward. Bacterial flagella can be located at one end, both ends, or all around the cell. This allows them to move toward food or away from toxins.
In addition to flagella, other filamentous appendages that bacteria can have include fimbriae and pili, but these are not primarily for movement. While cilia are short, hair-like structures found on some eukaryotic cells and are used to move cells or substances along their surface, they are not found on bacteria. Pili are also protein appendages found on bacteria but are mainly used for attachment to surfaces or for DNA transfer, not for locomotion.