Plasmolysis experiment onion cell. CBSE Class 11 Exam 2022: Syllabus, Marking Scheme 2022-10-14

Plasmolysis is a phenomenon that occurs when a cell's cytoplasm loses water and shrinks away from the cell wall. This process can be observed in plant cells, such as those found in an onion. The plasmolysis experiment is a common exercise in biology labs, and it provides insight into the properties of plant cells and the mechanisms that regulate the movement of water across cell membranes.

To conduct a plasmolysis experiment, an onion is first cut and a thin slice is prepared. The slice is then placed in a petri dish or other suitable container, and a drop of water is added. The water will cause the cells to swell as they take in water, a process known as turgor.

Next, a concentrated salt solution is prepared. This solution has a higher concentration of dissolved ions than the cells inside the onion slice, and it will cause the cells to lose water by osmosis. The slice is then placed in the salt solution, and the process of plasmolysis can be observed under a microscope.

As the cells lose water, the cytoplasm will shrink away from the cell wall, creating a visible gap. This gap is known as the plasmolytic space. The degree of plasmolysis can be measured by the size of the plasmolytic space, with a larger space indicating a more severe loss of water.

The plasmolysis experiment allows researchers to study the movement of water across cell membranes and the role of osmosis in regulating cell volume. It also provides insight into the ways that plant cells respond to changes in the concentration of dissolved substances in their environment.

In addition to its scientific value, the plasmolysis experiment is also a useful teaching tool, as it provides a hands-on opportunity for students to observe and understand the principles of osmosis and plant cell function. Overall, the plasmolysis experiment is a valuable and informative exercise that helps to deepen our understanding of plant cells and the mechanisms that regulate their behavior.