Download DATA AND OBSERVATIONS: Draw all of the cells that you see

Name: _________________________Pd: _______Seat#_____ Color ____________
Plasmolysis of Plant Cells: Pre-lab Activity
Read over the “Plasmolysis of Plant Cells”. Answer the following questions in order to
prepare for your lab.
1. In your own words, describe plasmolysis.
2. When does plasmolysis occur?
3. In the box to the right, draw a picture of a plant cell
that has been plasmolysized. Make sure to label
the following: location of fresh H2O, Cell membrane,
cell wall.
4. Define osmosis.
5. List two of the objectives of this lab.
6. What is added to the Elodea leaf that causes plasmolysis to occur?
7. How will you know if plasmolysis occurred?
Plant Cells before plasmolysis
Plant Cells after plasmolysis
Cell
Membrane
Plasmolysis of Plant Cells
What is plasmolysis?
Plasmolysis occurs when a plant cell membrane shrinks away from its cell wall. This occurs
when water moves out of the plant cell.
Notice the cell membrane of the plant cell
pulling away from the cell wall. Label cell wall & cell
membrane in the picture.
This occurs when the cell loses water.
Background: Diffusion of water across a cell’s membrane is called osmosis. This movement of water
may be harmful to cells. If too much water is lost from the cell, the cell membrane and the cell contents
shrink away from the cell wall. This, remember, is called plasmolysis.
Objectives:
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Prepare a wet-mount slide of Elodea (plant) leaf.
Observe plasmolysis (pulling away of cell membrane from the cell wall) in the cell as salt
water is added.
Observe the reverse of plasmolysis as fresh water is added.
Materials:
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microscope
1 slide
1 cover slip
paper towel
foreceps
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Elodea leaf (freshwater
plant)
disposable pipettes
salt water
fresh water
Procedure:
_____ 1. Make a wet-mount slide of an Elodea leaf as described below:
- obtain a glass slide
- using forceps, place one Elodea leaf in the center of the slide
- using a pipette, place one or two drops of fresh water on the Elodea leaf
- carefully cover the leaf with a coverslip
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_____ 2. Place the slide on the stage of the microscope.
_____ 3. Observe the leaf under low, medium, and high powers. Note the location of the chloroplasts in
relation to the cell wall.
_____ 4. Draw the normal cells in fresh water in the space provided in the Data and Observation section
of this lab. Draw just what you see under the microscope. Label the cell wall, cell
membrane, and chloroplasts.
_____ 5. Using a pipette, add two to three drops of salt
water along the edge of the coverslip. Place a
piece of paper towel along the opposite edge of
the coverslip. The fresh water will soak into the
paper towel, pulling the salt water over the leaf
(see Figure 1).
Figure 1
_____ 6. Again note the location of the chloroplasts in relation to the cell wall. (If the membrane and
the cell contents have pulled away from the cell wall, this is plasmolysis.)
_____ 7. Draw the plasmolyzed cells in the space provided in the Data and Observation section of this
lab. Label the cell wall, cell membrane, and chloroplasts.
_____ 8. Add two drops of fresh water to the slide, following the procedure in step 5. Observe the
cells under the microscope.
Data and Observations: Draw all of the cells that you see under the microscope in the circles below.
In the first circle, draw the Elodea cells in tap water. Label the cell wall and the chloroplast. In the
second circle, draw the Elodea cells in salt water. Label the cell wall, cell membrane, and chloroplast.
Elodea cells in tap water.
Elodea cells in salt water.
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Analysis: Answer the following questions in complete sentences.
1. Describe the location of the chloroplasts in an Elodea cell in tap water.
2. Describe the location of chloroplasts in an Elodea cell after salt water was added to the slide.
3. Which direction did water move when the salt solution was added to the slide?
4. Which direction did water move when tap water was then added to the slide?
5. Why didn’t the cell wall collapse?
6. What process allowed the water to move across the cell membrane?
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