Mr. Croft
Honors Biology
Chapter 6 Lab: Osmosis
50 Points
Mr. Croft received a goldfish for Christmas and he accidentally placed it into a tank full
of salt water. Unfortunately, the fish did not live very long! After disposing of the fish, Mr. Croft
went to the pet store and purchased a new goldfish. He asked for advice from the pet store
worker. The worker told Mr. Croft that goldfish required a freshwater tank. So, Mr. Croft
hurried home and placed the goldfish in a tank full of distilled water. Once again, the fish died!
Why did Mr. Croft’s goldfish die both times?
Obviously, we cannot use living goldfish cells for this experiment. So, we will use the cells
from an Elodea Plant. This will allow you to observe the effects of both salt water and distilled
water on cells. Your job is to design and carry out an experiment that will explain why the
goldfish died in both solutions. Make sure that the experiment has a control!
I. Problem: What happens to cells that are placed in hypotonic and hypertonic solutions?
II. Hypothesis: Write your hypothesis before you begin writing your procedure.
III. Materials:
1. Microscope 5. Aquarium Water
2. 2 Slides 6. Salt Water
3. 2 Cover Slips 7. Distilled Water
4. Elodea Plant 8. Pipettes
IV. Procedure: Write a step-by-step procedure for this lab. Make sure that your experiment
has a control. Once your procedure is written, we will discuss the correct
procedure as a class.
V. Results: Draw a detailed picture of each slide that you observe (high power). Be sure to
note the magnification for each picture. Also, take notes on the appearance of
each slide.
VI. Conclusions: Write a good conclusion that answers the problem. Make sure that you
explain what happened during this experiment.
VII. Questions:
1. What cell structures do you see in your Elodea specimen?
2. Describe the position of the cell membrane and chloroplasts in each drawing.
3. Classify the three solutions as isotonic, hypotonic, or hypertonic. EXPLAIN!
4. If this experiment were done with living animal cells, what would you observe for each
solution?
5. How can you explain the occurrence of “streaming” chloroplasts?
A formal laboratory report (seven parts) is due two days after this lab. Reports must be neatly
written or typed. Late reports will be penalized 10% every day that they are late.
