Final answer:
Hair like extensions that enable bacteria to move are called flagella, which are tail-like structures that propel the bacteria forward by rotating. These flagella can reach speeds up to 50 µm/s and are essential for bacterial motility, allowing them to move towards nutrients or away from toxins.
Step-by-step explanation:
The hair like extensions that help certain bacteria move about are called flagella. Flagella are tail-like structures that rotate and propel bacteria forward, functioning similarly to a tiny whip. Notably, the speed at which bacteria can move using their flagella can be up to 50 µm/s (50×10-6 m/s). This remarkable form of movement is often utilized to navigate towards food or away from harmful substances, a behavior known as chemotaxis. Although flagella are more commonly associated with prokaryotic cells, few eukaryotic cells possess them too, although it's a rare occurrence.
Variations in the placement of flagella on bacterial cells include having them at one or both ends of the cell or distributed all around. In addition to flagella, some bacteria also possess other types of filamentous appendages such as fimbriae and pili, which aid in surface attachment and the transfer of genetic material, respectively. However, specifically for movement, flagella provide the essential motility function required by bacteria to travel through liquid environments.