The effect of extracellular salt concentrations on plant osmosis
Plant cell type: Elodea or Allium

Hypothesis:
Plant cell will become plasmolyzed (plasma membrane shrink away from cell wall) in hypertonic environment,
and will become turgid in hypotonic environment.

QUANTITATIVE DATA TYPES

1. % cell has shrunk
2. % cells plasmolyzed

Table 1 The effect of extracellular salt concentrations on plant osmosis. p. 104

Concentration of Salt Solution %         Quantitative Data
0%
0.9%
5%

1. How could you provide a control for this experiment?
   Use isotonic (0.9%, saline solution) as control.

2. As compared to the original preparation of distilled water (0% salt), how did the appearance of the cells change with increasing NaCl concentrations? Explain the changes. p. 105
   Cells should become plasmolyzed: plasma membrane shrinks away from cell wall.

3. Identify which concentrations were hypertonic, isotonic, and hypotonic.
   Hypertonic: 5%
   Isotonic: 0.9%
   Hypotonic: 0% (distilled)

4. How did the plant cells that had undergone plasmolysis differ in appearance from those that were turgid.
   Plasmolyzed cells show plasma membrane pulled away from cell wall.

5. Should cells of plants and animals react the same way if placed in the same concentrations of salt solution? Explain.
   Hypotonic environment: plant cells are turgid and healthy in ; animal cells will burst unless excess water is pumped out.
   Hypertonic environment: both types of cell will shrink.

6. Comment on your original hypothesis. Was it supported?
   Hopefully yes.

7. What is the importance of osmosis in the homeostasis of plant cells?
   Plants like to be watered to maintain hypotonic environment. Do not add salt to the soil!
   Osmosis is also how root cells take up water from the soil.

The effect of extracellular salt concentrations on animal osmosis

Hypothesis: Paramecium cells shrink in hypertonic environment, and will pump its contractile vacuoles in hypotonic environment.

Table 1 The effect of extracellular salt concentrations on animal osmosis.

Concentration of Salt Solution %         Quantitative Data
0%
0.9%
5%

8. As indicated by your observations, explain what happens to the pumping rate of the contractile vacuole as the concentration of salt increases.
   Pumping rate should decrease as concentration of salt increases.

9. If contractile vacuoles were not present or failed to function properly, what would happen to the Paramecium in a hypotonic environment?
   It would lyse (burst).

10. As the salt concentration increases to a hypertonic state of 5% or 10% NaCl, what happened to the appearance of Paramecium?
    Cells should shrink.

11. Based on your data, is there a lethal salt concentration to Paramecium?
    5% is lethal if exposure is prolonged for several minutes.

12. Comment on your original hypothesis. Was it supported?
    Hopefully yes.