When a plant cell is placed in an isotonic solution, there is no net movement of water into or out of the cell. This happens because the concentration of solutes outside the cell is equal to the concentration of solutes inside the cell.
As a result, the plant cell maintains its shape and size since the osmotic pressure is balanced. The cell’s vacuole, which holds water, remains full enough to provide turgor pressure, but it won’t become overly swollen or lose water.
In essence, the plant cell remains healthy and turgid in an isotonic environment, ensuring that its cellular functions can continue normally without the risk of plasmolysis, which can occur in hypertonic solutions, or bursting, which can occur in hypotonic solutions.