Plasmolysis: Plasmolysis is the process by which a plant cell loses water when placed in a hypertonic solution(a solution having a higher amount of solutes than the cell). The actual process behind this is the movement of water outwards due to osmosis, resulting in the shrinkage of the entire cell. As osmosis requires zero energy, Plasmolysis becomes an out-of-control process, even though excessive water loss can lead to the collapse of the cell wall.

Types of Plasmolysis

• Concave Plasmolysis:  In this, both the protoplasm and the plasma membrane shrinks and detaches from the cell wall. Due to the detachment of protoplasm( then called protoplast), a ‘half-moon-shape’ is formed in the cell. Nonetheless, concave plasmolysis can be reversed by placing the cell in a hypotonic solution.
• Convex Plasmolysis: This is an irreversible process. The excessive loss of water from the cell loosens the plasma membrane and protoplasts, leading to the detachment from the cell wall. As this process cannot be reversed, it results in the destruction of the cell. Hence, this is what happens when a plant withers and dies from lack of water.

Stages of Plasmolysis

The complete process of Plasmolysis take place in three different stages:

• Incipient plasmolysis: It is the initial stage of the plasmolysis, during which, water starts flowing out of the cell; initially, the cell shrinks in volume and cell wall become detectable.
• Evident plasmolysis: It is the next stage of the plasmolysis, during which, the cell wall has reached its limit of contraction and cytoplasm gets detached from the cell wall attaining the spherical shape.
• Final plasmolysis: It is the third and the final stage of the plasmolysis, during which the cytoplasm will be completely free from the cell wall and remains in the centre of the cell.

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By Team Learning Mantras