Final answer:
Microvilli and stereocilia serve important functions in the body, such as enhancing absorption in the small intestine and contributing to hearing and balance.
Step-by-step explanation:
Microvilli are cylindrical extensions of the plasma membrane of the mucosa's epithelial cells that greatly enhance absorption in the small intestine. They are supported by microfilaments and have enzymes that finish digesting carbohydrates and proteins. On the other hand, stereocilia are hair-like extensions of hair cells in the organs of Corti and maculae. They bend in response to movements, triggering nerve impulses that help with hearing and balance.