Answer :
Final answer:
One external structure that successful pathogens have to attach to surfaces is fimbriae, Another structure, similar but longer is pili and it is It is composed of pilin protein.
Explanation:
Fimbriae and pili are both structures found in certain bacteria that aid in attachment to surfaces, but they serve slightly different functions. Fimbriae are short, bristle-like structures composed of protein subunits called pilin, which extend from the surface of the bacterial cell. They help bacteria adhere to surfaces such as host tissues or other cells.
Pili, on the other hand, are longer appendages also composed of pilin protein. Pili have a more specialized role, often involved in processes such as bacterial conjugation (the transfer of genetic material between bacteria) or twitching motility (a form of bacterial movement).