Final answer:
Cilia are short, hair-like structures found in some eukaryotic cells. They are used for movement and can sweep particles past or into cells. For example, cilia in the mammalian respiratory tract help remove mucus and debris from the lungs.
Step-by-step explanation:
Cilia (singular: cilium) are a similar external structure found in some eukaryotic cells. Unique to eukaryotes, cilia are shorter than flagella and often cover the entire surface of a cell; however, they are structurally similar to flagella (a 9+2 array of microtubules) and use the same mechanism for movement. In addition to motility, cilia may have other functions such as sweeping particles past or into cells. For example, ciliated protozoans use the sweeping of cilia to move food particles into their mouthparts, and ciliated cells in the mammalian respiratory tract beat in synchrony to sweep mucus and debris up and out of the lungs.