Question

The motile bacteria are able to move by:

• A. Flagella
• B. Cilia
• C. Pili
• D. Fimbriae

Answer 1

The Correct Option is A

The motile bacteria are able to move using structures called flagella. Let's explain this correctly by evaluating why flagella are the answer and understanding the roles of each option given.

1. Flagella:
   • These are long, whip-like appendages that protrude from the cell body of certain bacteria.
   • Flagella are primarily responsible for locomotion, allowing bacteria to swim through liquid environments.
   • The motion of flagella is typically rotational, which propels the bacterium forward or backward, providing it with mobility.
2. Cilia:
   • These are shorter than flagella and more numerous.
   • Cilia are found in eukaryotic cells (such as those in the human respiratory tract) but not in prokaryotic cells like bacteria.
   • Thus, cilia are not typically involved in bacterial motility.
3. Pili:
   • Pili are hair-like structures on the surface of bacteria.
   • They play roles in attachment to surfaces, conjugation (exchange of genetic material between bacteria), and slight twitching movements.
   • However, pili are not responsible for bacterial motility in the same way flagella are.
4. Fimbriae:
   • Fimbriae are similar to pili and are involved in adherence to surfaces and to host cells.
   • They are not involved in motility.

Thus, the correct answer is flagella, as it is the structure that enables motile bacteria to move. Understanding the differences between these structures is essential, especially in microbiology.