What is the function of a flagellum in a bacterium?

• A. It has a role in reproduction.
• B. It helps in locomotion.
• C. It contains the organism's organelles.
• D. It secretes the cell wall.

Answer: (B)

Flagellum enables movement. It is a whip-like tail attached to the cell that rotates, acting as a propeller to drive the bacterium through liquid. This locomotion lets bacteria swim toward nutrients and away from harmful substances, a behavior called chemotaxis. The flagellum isn’t used for reproduction, doesn’t house the cell’s organelles, and doesn’t secrete the cell wall. Those tasks are carried out by other cellular processes. So the flagellum’s primary function is to propel the cell and enable movement.