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Introduction: One of the functions of the cell membrane is to control the flow of materials into and out of the cell. In this investigation, you will observe the effects of placing plant cells in solutions of various concentrations.
Materials:
Elodea leaves, microscope slides, cover slips, microscope,
distilled water, tap water, 5% salt solution, 10% salt solution,
paper towel.
Methods:
Prepare a wet mount of an Elodea leaf with tap water. Observe
the leaf at 40X and record your observations. Increase the magnification
to 100X, observe, and record your observations.
Remove the slide from the stage of
the microscope. Place 2 drops of the 5% salt solution on the slide
at the edge of the cover slip. Tear off a small piece of paper
towel and place the torn edge on the slide at the edge of the
cover slip that is opposite the side where the salt solution was
placed. The piece of towel should begin to soak up water, drawing
the salt solution under the cover slip as it does so.
Methods (continued):
Return the slide to the microscope stage and repeat the observations
of the cells at 40X and 100X. Record your observations. Repeat
the above procedure. Record your observations. Remove the slide
from the stage, clean it and the cover slip, and put it away.
Put the microscope on low power and put it away.
Observations:
Prepare sketches of a group of Elodea
cells under each set of conditions. Label the sketches to
note the cell structures that you can identify. Be sure to note
any changes in the color, size, and shape of the cells. Make your
sketches as accurate as possible.
Conclusions:
Answer the following questions.
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Science Education Connection Department of Biochemistry The University of Arizona Wednesday, February 12, 1997 johnmcc@dakotacom.net
http://biology.arizona.edu/sciconn/lessons/mccandless/ |
