Final answer:
If a paramecium's contractile vacuole were to stop working, the paramecium would likely swell up and lyse.
Step-by-step explanation:
If a paramecium's contractile vacuole were to stop working, the paramecium would likely swell up and lyse.
The contractile vacuole is responsible for regulating the water balance within the cell by pumping out excess water.
Without this mechanism, water would accumulate inside the paramecium, causing it to swell and eventually burst.