The situation that is NOT an example of how homeostasis is maintained by cells is:
The cell membrane allows too much water into the cell after the vacuoles are full, which causes the cell to swell and burst.
This situation describes a failure of homeostasis, as the cell is unable to regulate its internal environment properly, leading to potential cell damage or death. Homeostasis involves maintaining stable internal conditions, and a cell bursting due to excessive water intake indicates a breakdown of that regulation.