Osmosis: Cell Wall and Salt Water Solution

Diffusion is when substances spread throughout a liquid or a gas (high to low). Osmosis is the diffusion of water through a selectively permeable membrane (a type of diffusion). In plant cells it is also referred to as plasmolysis. Plasmolysis affects the cells ability to work properly (homeostasis). Plant cells are homeostatic when their central vacuole is filled with water. Surrounding a plant cell are two layers called the cell wall and the cell membrane. Plant cells respond to the solutions surrounding their membrane. The two parts of a solution are the solvent and the solute.

The solution that surrounds the plant cell is either a hypotonic solution or a hypertonic solution. Hypertonic solutions cause the plant cell to shrink when exposed to it. Hypotonic solution is the opposite and causes the plant cell to swell up. In plant cells they don’t burst when exposed to hypotonic solutions because of the cell wall. Hypothesis: If 10% salt water solution effects Elodea leaves then the cell of the plant will shrink in the salt water solution. Materials:

Elodea leavesmicroscope10% salt solution
Microscope slidesdistilled waterpaper towel
Coverslipstap waterdigital camera
Procedure: Please see lab handout.

Data:
Elodea densa
Fresh Water
Magnification- 400x
Elodea densa
Fresh Water
Magnification- 400x

Cell membrane
Cell membrane
Chloroplast
Chloroplast
Cell wall
Cell wall

Elodea densa
Salt water
Magnification– 400x
Elodea densa
Salt water
Magnification– 400x

Cell membrane
Cell membrane

Cell wall
Cell wall

Chloroplast
Chloroplast

Conclusion:
If 10% salt water solution effects Elodea leaves then the cell of the plant will shrink in the salt water solution. The hypothesis was supported. This is because if you look at the pictures in the data it shows the cell shrinking when salt water was added to the leaf. When regular water was added to the Elodea densa leaf you could see more chloroplast then when there was salt water added. This is because the salt water solution is hypertonic. The effect of placing an Elodea cell in a hypertonic solution is the cell to shrink; all the organelles and parts in the cell then become closer together because of the shrinking cell. When the Elodea cells were exposed to distilled water it showed the chloroplast spreading back out as well as the cell swelling because distilled water is a hypotonic solution. The Elodea cells were the most turgid with the regular water solution and the distilled water solution.

When the in a produce section of a supermarket many vegetables on display are spray down automatically with water. The effect on this is that it keeps the vegetables fresh and yummy to eat. If yeast was also used in this experiment it probably would have had the same effect because it has a cell wall. Because red blood cells aren’t plant cells they do not have a cell wall. There for they would burst unlike a plant cell. When a red blood cell is exposed to a hypertonic environment the water flows out of the cell. This causes them to shrink and collapse, making a spiky appearance. When the red blood cell is exposed to a hypotonic environment the water rushes into the cell causing it to swell. They become so swollen that a lot of them rupture or burst.