Osmosis: Cell Wall and Salt Water Solution

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Objective: Observe response of Elodea densa cells to a salt solution. Background Information:
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...
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