Paramecia and amoebas lack cell walls. What structure keeps them from bursting in a hypotonic medium?

1. Paramecia and amoebas are protists that lack cell walls, so they cannot rely on a wall to stop lysis. 2. They have contractile vacuoles instead. 3. A contractile vacuole collects excess water from the cell and pumps it out, keeping the cell from lysing as it takes on water. 4. Lysosomes digest material, lipid rafts organize proteins, and clathrin coats membrane for endocytosis, so none of them handles water balance. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 5 "Structure and Function of Plasma Membranes", section 5.2 Passive Transport_