Biology I
Name___________________________
Lab Activity
Date______________
Pd________
Osmosis
Prelab:
1. Define osmosis.
2. Compare the terms: hypotonic, isotonic, and hypertonic.
Procedure:
1. Prepare a wet mount of a tip from an elodea leaf, using water from its beaker.
2. Observe under low power. Scan to find some distinct large cells, center, and raise to high power
(400X). Use lid to draw circle. Draw and label all observed cell parts.
3. Now place a piece of paper towel to one side of the cover slip while you add drops of salt water to
the other side. Repeat several times. Make sure the salt water washes over the cell thoroughly.
4. Repeat step 2 but make sure you have observed changes in the cell before sketching.
5. Repeat step 3 using distilled water. Flush the slide several times thoroughly.
6. Repeat step 2 but again wait and observe changes before sketching.
Observations:
Attach paper with 3 labeled sketches.
Conclusions:
1. Describe the changes you observed when you added the salt water. Why did they occur? Use
correct terminology
2. Would elodea be able to live in a marine environment? Explain your answer.
3. Describe the changes you observed when you added the distilled water. Explain why they occurred.
Use correct terminology.
4. Were these changes the result of active or passive transport? Explain.
5. Explain how and why your results would have differed if you had used animal cells rather than plant
cells?
6. Explain why they spray water on the produce at the market. Use scientific terminology.
7. Why does using too much fertilizer on your grass kills it. Use scientific terminology.