Which of the following is false about fimbriae?
a. They are composed of protein.
b. They may be used for attachment.
c. They are found on gram-negative cells.
d. They are composed of pilin.
e. They may be used for motility.

Fimbriae are thin, hair-like appendages on the surface of many bacteria, primarily composed of the protein pilin. They differ from flagella in size and function, being shorter and more numerous, and their protein composition allows them to mediate specific interactions with surfaces or host cells.

Fimbriae primarily function to help bacteria adhere to surfaces, including host tissues, which is crucial for colonization and infection. This attachment ability distinguishes fimbriae from other appendages like flagella, which are mainly involved in movement.

Fimbriae are commonly found on gram-negative bacteria, where they play a key role in pathogenicity. While some gram-positive bacteria may have similar structures, fimbriae are most characteristic and well-studied in gram-negative species.