Final answer:
Fimbriae are short, numerous, and help cells attach to surfaces and other cells, while flagella are long, fewer in number, and enable cells to move in aqueous environments.
Step-by-step explanation:
Fimbriae and flagella are two types of appendages found in prokaryotic cells that have different structures and functions. Fimbriae are short, bristle-like protein structures that can be found by the hundreds projecting from the cell surface. Their main function is to enable a cell to attach to surfaces and other cells, which is crucial for pathogenic bacteria in terms of colonization, infectivity, and virulence, as well as for biofilm formation. In contrast, flagella are long, whip-like structures used for cell movement in aqueous environments. They are composed of flagellin protein subunits and are less numerous than fimbriae. The flagellum operates like a propeller, with a motor called the basal body embedded in the plasma membrane and a hook region that connects the basal body to the filament, helping the cell to move purposefully towards chemical attractants.