Water balance problems in the animal cells:

OR

Animal cell in the hypotonic environment:

1. When an animal cell, such as the red blood cell, is placed in an isotonic solution, the volume of the cell remains constant because the rate at which water is entering the cell is equal to the rate at which it is moving out.
2. When a cell is placed in a hypotonic solution (which has a lower salt concentration than the cell) water enters and the cell swells and may rupture like an over-filled balloon.
3. An animal cell placed in a hypertonic solution (which has a higher salt concentration than the cell) will lose water and will shrink in size.
4. So in hypotonic environments (freshwater) animal cells must have ways to prevent the excessive entry of water and in hypertonic environments (seawater) they must have ways to prevent excessive loss of water.

Water balance problems in plant cells:

OR

Plant cell in the hypotonic environment:

1. Most plant cells live in a hypotonic environment because there is a low concentration of solutes in extracellular fluids than in their cells. As a result, water tends to move first inside the cell and then inside the vacuole.
2. When the vacuole increases in size the cytoplasm presses firmly against the interior of the cell wall, which expands a little.
3. Due to the strong cell wall, plant cell does not rupture but instead becomes rigid. The internal pressure of such a rigid cell is known as turgor pressure and this phenomenon is known as turgor.
4. In an isotonic environment the plant cells are flaccid (loose / not firm) because the net uptake of water is not enough to make it turgid.
5. In a hypertonic environment a plant cell loses water, causing the cytoplasm to shrink within the cell wall. The shrinking of cytoplasm is called plasmolysis.