guts
houses, hospitals, flats and me
If the solute concentration outside the paramecium matched that inside, the surrounding environment would become isotonic to the paramecium's internal environment. In this scenario, there would be no net movement of water into or out of the paramecium, preventing any osmotic stress. The paramecium would maintain its shape and volume, as the balance of osmotic pressure would stabilize its internal conditions.
the Kingdom Protista, and the PhylumEuglenophyta
In the ponds, in lentic waters
These are fresh water protists. Lakes, streams and ponds would harbor paramecium and amoebae.
The paramecium would have difficulty regulating its water balance, leading to swelling and potential bursting from an influx of water. Without a contractile vacuole, the paramecium would struggle to expel excess water and maintain osmotic balance, ultimately leading to cell damage or death.
in fresh water
Many things. For instance, you probably couldn't find a medium-sized toaster oven in a paramecium cell.
The activity of the contractile vacoule would decrease. While in the hypotonic solution, water was moving into the paramecium because it had a higher solute concentration that the solution that it was in and water follows solute. So, the isotonic solution would contain the same solute concentration as the paramecium so there would be no net water movement. Therefore, the contractile vacoule would decrease in its activity because there would be no water entering or exiting the paramecium.
By osmosis
See excellent related answers below.
The scientific name for paramecium is Paramecium spp.