Final answer:
Cilia are short, hairlike projections found on some eukaryotic cells. They have various functions such as locomotion and moving extracellular particles. An example of their function is seen in the respiratory tract where ciliated epithelial cells use cilia to push mucus and debris away from the lungs.
Step-by-step explanation:
Cilia (singular: cilium) are short, hairlike projections found on some eukaryotic cells. They are composed of microtubules in a 9+2 array and have various functions such as locomotion, feeding, and moving extracellular particles. For example, ciliated epithelial cells in the respiratory tract use cilia to push mucus secretions and trapped debris away from the lungs.