Final answer:
A malfunction in the contractile vacuoles of a cell would prevent the expulsion of excess water.
Step-by-step explanation:
A malfunction in the contractile vacuoles of a cell would affect the cell by preventing the expulsion of excess water. The contractile vacuoles in a cell are responsible for the excretion of excess water and waste through the process of exocytosis. Without properly functioning contractile vacuoles, the cell would be unable to expel the excess water, leading to an accumulation of water within the cell.