Final answer:
Plant cells become turgid when exposed to excess water, which stiffens the cell walls and helps maintain plant structure. The central vacuole is key in regulating water content, leading to a turgid state that supports the plant or, conversely, to plasmolysis and wilting if water is scarce.
Step-by-step explanation:
When plant cells are exposed to excess water in their environment, they experience changes in turgor pressure due to osmosis. Water enters the plant cells through the semi-permeable plasma membrane, swelling the central vacuole, which leads to an increase in turgor pressure. This influx of water makes the plant cells turgid, stiffening the cell walls and supporting the structure of the plant. The central vacuole in plant cells plays a critical role in regulating water concentration within the cells, ensuring that plant tissues can recover from both over-watering and under-watering scenarios. If a plant is over-watered, cells become overly turgid which can make them brittle, whereas in under-watered plants, cells can undergo plasmolysis, where the plasma membrane detaches from the cell wall, and the plant becomes flaccid or wilted, losing its structural rigidity.