Homeostasis is the regulation of internal conditions, for example, when you get hot you sweat to keep a stable body temperature. In this case, you are looking for what is regulating conditions inside the cell. The semipermeable membrane within the cell regulates what goes in and out of the cell to make sure that it doesn't take in or give up too many nutrients, and lysosomes get rid of bacteria in the cell so it can continue to function.
