National League for Nursing (NLN PAX) Practice Exam

Protozoans are characterized by their ability to move, and many of them swim using cilia, which are microscopic hair-like structures that beat in a coordinated manner to propel the organism through liquid environments. This swimming capability is one of the defining features of many protozoans, facilitating their movement and interaction with their environment, such as in finding food or escaping predators. The other options represent characteristics associated with different types of organisms rather than protozoans. For instance, being multicellular is typical of more complex organisms like animals and plants, but protozoans are unicellular. They also do not have cell walls; instead, protozoans have flexible membranes that allow for various forms of movement, including swimming, while organisms that do have cell walls are typically found in the plant kingdom or among fungi. Lastly, protozoans are classified within the kingdom Protista, not the plant kingdom, which further distinguishes them from plant organisms.