Plasmolysis Failure in Boiled Rhoeo Leaf Cells

Plasmolysis is the shrinking of the cell's protoplast away from the cell wall due to water loss by osmosis into a hypertonic environment. This process depends on the cell being alive and having a functional, selectively permeable plasma membrane.

Effect of Boiling on Plant Cells

Boiling kills plant cells. The heat damages the cell structures, particularly the plasma membrane, rendering it non-functional and non-selectively permeable.

Reason for Lack of Plasmolysis

When boiled Rhoeo leaf peels are placed in salt solution, plasmolysis does not occur because the cells are dead.

• Dead cells cannot regulate the movement of water across their membranes (cannot osmoregulate).
• The plasma membrane is damaged and loses its selective permeability, which is essential for osmosis to cause plasmolysis.

Evaluating Other Options

• Chlorophyll takes up water: Chlorophyll's function is photosynthesis; it does not influence plasmolysis by taking up water.
• Walls block salts: Cell walls are fully permeable to water and dissolved solutes like salt.
• Nuclei stop diffusion: While the nucleus is vital for living cells, its primary role isn't to stop diffusion in a way that prevents plasmolysis, and boiling damages it anyway. The membrane's state is key.

The fundamental reason is that dead cells cannot perform the regulated water movement (osmoregulation) required for plasmolysis.