Plasmolysis in a plant cell is defined as _______.

shrinkage of cytoplasm in hypertonic medium

Plasmolysis in a plant cell is defined as the shrinkage of the cytoplasm when the cell is placed in a hypertonic medium. This process occurs due to the loss of water through osmosis, causing the plasma membrane to contract and separate from the rigid cell wall. The movement of water out of the cell is driven by the higher solute concentration in the surrounding medium compared to the cell's internal environment.

This phenomenon is a key indicator of osmosis in plant cells and is observed in the following stages:

• Incipient Plasmolysis: The initial stage where the plasma membrane begins to detach from the cell wall but is still partially attached at certain points.
• Full Plasmolysis: The stage where the plasma membrane completely pulls away from the cell wall, leading to a visible gap between the cell wall and the shrunken cytoplasm.

Plasmolysis is a reversible process. When a plasmolyzed cell is placed in a hypotonic solution, water enters the cell through osmosis, restoring the turgor pressure and returning the cell to its normal state. This reversibility is crucial for plant cells to recover from dehydration conditions.

Key Concept: Plasmolysis highlights the osmotic behavior of plant cells in hypertonic environments. It is a practical demonstration of the semi-permeable nature of the plasma membrane and the importance of turgor pressure in maintaining cell structure and function.