Name: ___________________________________________________________ Bell: _________ Date: _____________
1. Describe the egg. Include as many details as you can.
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2. Make a prediction about what you think will happen to the egg when it is placed in: a. Distilled water- _______________________________________________________ b. Distilled water with food coloring - ________________________________________ c. Salt water - __________________________________________________________ d. Light corn syrup - _____________________________________________________
3. Complete the following data table:
Liquid
Distilled Water
Distilled water with food coloring
Salt Water
Light corn syrup
Day 1
Day 2
Day 3
Day 4
Day 1
Day 2
Day 3
Day 4
Day 1
Day 2
Day 3
Day 4
Day 1
Day 2
Day 3
Day 4
Initial
Volume
(mL)
Final
Volume
(mL)
Final
Mass
(g)
Initial
Mass
(g)
Observations
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Scientists recognize the relationship between solutions and the internal environments of a cell.
They use special terms to describe the similarities and differences between the contents of the external environment and the internal environment of a cell.
Review your notes concerning isotonic, hypertonic, and hypotonic solutions. Also recall which substance in a solution is classified as a solute and which is a solvent.
Procedure:
To observe the responses of plant cell, prepare a wet mount of Elodea by following these steps:
1. Use forceps to remove one leaf from an Elodea plant.
2. Lay the leaf flat on a clean slide.
3. Add one drop of tap water to the slide.
4. Stand a thin glass cover slip on its edge near the leaf, next to the drop of water.
5. Slowly lower the other side of the cover slip until it covers the leaf completely. Make sure there are no air bubbles.
6. Make sure the lowest power lens (the shortest) is in place over the stage. Place the slide onto the stage of the microscope.
7. Look through the eyepiece and turn the coarse focus knob (the largest) until an image comes into focus. It should look like small green bricks.
8. Now use the fine focus knob (the smallest knob) to make the image as focused as possible.
9. Looking from the SIDE of the microscope, rotate the lenses to the 100x lens. If you need to, use the fine focus knob (the smallest knob) to get the image into focus. You should be able to see lots of small green dots in each cell.
10. Again, looking from the SIDE of the microscope, rotate the lenses to the 400x lens. If you need to, use the fine focus knob (the smallest knob) to get the image into focus. The little green dots should get larger.
11. In the table on your lab sheet, draw a picture of what you see.
12. Place a small piece of paper towel at one edge of the cover slip.
13. Test the effects of changing the external environment of the cells you are viewing. To do this, place several drops of 5 percent salt solution against the edge of the cover slip opposite from the paper towel.
Observe what happens and record it on your lab sheet.

Add more salt solution, if necessary, until you see changes in the cells.
14. Dilute the salt solution on the slide by adding distilled water until the cells return to their original condition. Make observation while you do this, and record them on your lab sheet.
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15. Switch to the lowest power lens and THEN remove the slide.
16. Complete the Analysis questions on your lab sheet.

Name: _____________________________________Bell: ______ Date: ____________
Original Slide
Observation of Elodea in salt solution:
5% Salt Distilled Water
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Observation of Elodea in distilled water: -
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Analysis:
1. What evidence did you collect that indicates that the external environment affects the internal environment?
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2. In this activity, how did the egg serve as a model of how cells function as containers in living organisms?
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3. What do eggs, animal cells, plant cells, and the human body have in common?
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