What is crenation? Give an example.

Crenation is a process that occurs when a cell is exposed to a hypertonic solution, which is a solution that has a higher concentration of solutes outside the cell than inside the cell. This causes water to move out of the cell through osmosis in an attempt to balance the concentration of solutes. As a result, the cell shrinks and its surface appears to be notched or scalloped, a condition referred to as crenation.

An example of crenation can be seen in red blood cells. If red blood cells are placed in a hypertonic solution, such as salt water, they will lose water, shrink, and undergo crenation. This can be harmful and potentially lethal to the cells, which is why it's important for bodily fluids to maintain an isotonic condition, where the concentration of solutes is the same inside and outside the cells.