CBSE Class 9 Answered

 Crenation is the process of shrinking of a cell, after exposure to hypertonic cell, due to loss of water through exosmosis. It gives a notched appearance to the cell. Crenation can be seen prominently in case of red blood cells, which have undergone exosmosis.

Plasmolysis occurs in plant cells. Here,  the cytoplasm shrinks from the cell wall in a hypertonic environment.

Flaccidity means to lack firmness, resilience, or muscle tone.

In botany, flaccidity is the loss of rigidity (turgor) in plant cells, caused by loss of water from the central vacuole so that the cytoplasm no longer pushes against the cellulose cell wall. Flaccidity can be induced by immersing plant cells in strong saline solution, due to which water leaves the cell by osmosis, causing the vacuole to shrink.

When red blood cells are placed in a hypotonic solution, there is a gain in the internal fluid which finally leads to the breakdown or destruction of RBCs, with the release of hemoglobin. This process is called hemolysis.