-tonic

Explain the terms: hypotonic, hypertonic or isotonic in relationship to the internal environments of cells. Illustrate each environment with a model and explain which environment is best for plant and animal cells. Justify and explain your model with evidence.

Hypotonic - Cells expand in this environment, because there is less solute outside the cell than there is inside. In an attempt to reach equilibrium, the fluid outside the cell will enter the cell to even out the solute-to-volume ration. This causes cells to swell because there is more fluid within the cell than there usually would be, there is more volume. This can cause animal cells to burst, [lysed] as they do not have cell walls to provide a hard casing. Plant cells love hypotonic solutions because they are able to fill up their vacuoles and internal environments with water and other substances. This gives plants structure and rigidity [turgid].

Hypertonic Solution - Cells shrivel up in this environment, because there is more solute outside the cell than there is inside. In an attempt to reach equilibrium, the fluid within the cell will exit and flow outside, to even out the solute-to-solution ratio. This causes cells the shrivel up because there the fluid that once gave the cell structure is now gone. In animal cells, this is called a shriveled cell. In plant cells, this is called a plasmolyzed cell.

Isotonic - Cells are at a normal state, the amount of solute outside and inside the cell is even. Animal cells and plant cells are both gaining and losing water in this state. This is the ideal state for animal cells; a constant exchange with the environment. But, this is not the ideal state for plant cells. Plant cells do not want to have a constant exchange of water, they want to retain water. If they are unable to retain water, plants will be limp.

Mastering Biology | Pearson; Campbell Biology