Prepare two microscope slides – one with a drop of RO water, and one with a drop of 10% NaCl solution.
Use the forceps to remove two leaves from the tips of Elodea plants. Mount one leaf on each of the prepared microscope slide and place cover slips over the leaves.
Observe the leaf in RO water with the compound microscope. First focus with the medium power objective, and then switch to the high-dry objective for closer observation. Sketch several cells in the space provided to the right.
Now observe the leaf mounted in the 10% NaCl solution. Sketch several cells. After several minutes in the 10% NaCl solution the protoplasm of the cells has contracted because they have lost water – they have become plasmolyzed (the process is called plasmolysis).
After you have sketched the plasmolyzed Elodea cells, remove the microscope slide from the microscope and place it on a table. Add a drop of RO H2O right next to the cover slip and wick the RO H2O under the cover slip with the help of a Kimwipe. Then observe the response of the Elodea cells to the change in ambient solution; what happens?
Answer the following questions:
1.Considering the Elodea cells in RO H2O – were the contents of the vacuole hypotonic, isotonic, or hypertonic compared to the water?
2.Considering the Elodea cells in the 10% NaCl solution – were the contents of the vacuole hypotonic, isotonic, or hypertonic compared to the NaCl solution?
3.By exchanging solutions back from NaCl to RO H2O, were you able to reverse the effect that the 10% NaCl solution had on the Elodea cells? Why or why not?
4.If a hypotonic and a hypertonic solution are separated by a selectively permeable membrane, which direction will the water move?
5.Name two selectively permeable membranes that were involved in the plasmolysis process you just observed.

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1 The vacuoles of Eldoea cells in RO H 2 O contain isotonic solution because the salt concentration ... View the full answer