Final answer:
Plant cells in a hypertonic environment lose water through osmosis, leading to plasmolysis and loss of turgor pressure, which causes the plant to wilt.
Step-by-step explanation:
When a plant cell gets smaller through osmosis, this usually happens because the cell is in a hypertonic environment, causing water to leave the cell.
This process is known as plasmolysis, where the plasma membrane pulls away from the cell wall as it loses water, causing the cell to shrink. In this state, the plant may appear wilted due to the loss of turgor pressure, which is crucial for maintaining plant structure and support.
Plants have a cell wall that prevents them from bursting in hypotonic conditions by constraining the expansion of the plasma membrane.
Conversely, the cell wall does not prevent shrinkage in hypertonic conditions, but because the wall is rigid, it does not contract; instead, it is the plasma membrane that detaches, leading to plasmolysis.
Continuous water supply is needed, not only for metabolic processes like photosynthesis but also to maintain turgor pressure that keeps the cells and, consequently, the plant firm.