BIOL 1107L
Diffusion and Osmosis
DIFFUSION AND OSMOSIS
LAB OBJECTIVES
The following laboratory objectives will be carried out on the day of the lab. Data collected
during the lab may need to be analyzed at home, depending on how long it takes to complete
these lab objectives. Regardless, these objectives should be completed prior to next week’s lab
as they may covered in a lab quiz and are required to be recorded into your lab notebook.
Additionally, any data collected during the lab should be recorded into your lab notebook.
Exercise 1, Experiment A will be set up as a demonstration by your instructor.
You will be required to write a lab report on Exercise 1, Experiment B and Exercise 3,
Experiment A. Be sure to follow the posted grading rubric. Make sure you print the posted
grading rubric for this lab report and attach it to your completed lab report. Your lab report will
not be graded without the rubric. The rubric would be a good checklist to make sure that you
have included all of the expected items in your lab report.
Exercise 1, Experiment A (Not part of the lab report - Demonstration set up by instructor)
1. This experiment is NOT part of the lab report, but it still belongs in your lab notebook.
2. Observe Brownian movement of particles under the microscope and record what you see in
your lab notebook.
Exercise 1, Experiment B (This is also part of your lab report.)
The following objectives should be included in your lab notebook. They will also help you
write the “results” section of your lab report.
3. Briefly (a paragraph) describe how the experiment was carried out.
4. Record your data in table form in your notebook
5. Record the contents and colors of the bag and beaker when you set up the experiment.
6. Record the color of the bag and beaker after the experiment.
7. Record the color of the samples before and after the Benedict’s test
8. State what I2KI and Benedict’s Test detect.
The following objectives should be included in your lab notebook. They will also help you
write the “discussion” section of your lab report.
9. Discuss whether starch, glucose, and/or iodine (I2KI) are able to diffuse through the dialysis
tubing.
10. Rank the molecules by size and discuss why you ranked them this way.
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BIOL 1107L
Diffusion and Osmosis
11. Which molecule(s) is the dialysis tubing selectively permeable to? How/why did you come
to this conclusion?
12. Give a conclusion statement and state whether your hypothesis was supported or rejected.
What evidence from the data to supports your conclusion? D
13. Discuss any unexpected results (if applicable). Are there any possible explanations for the
finding(s)?
Exercise 2, Experiment A (Not part of the lab report - Demonstration set up by the instructor)
14. The NaCl concentration in red blood cells is 0.85M. Which solution is hypertonic to the red
blood cells? Which solution is isotonic to the red blood cells? Which solution is isotonic to the
red blood cells?
15. Record the data from your observations and sketch a picture of red blood cells in
hypertonic, hypotonic, and isotonic solutions in your notebook.
16. Be able to identify the characteristics of red blood cells in hypertonic, isotonic, and
hypotonic solutions. List the characteristics of red blood cells in hypertonic, isotonic, and
hypotonic solutions in your notebook.
Exercise 3, Experiment A. (This is also part of your lab report)
17. Know how to properly use the balance to weigh an item (Practical application—you do not
have to write anything down in your notebook unless you wish to describe the steps for how to
do this procedure).
18. How do you calculate the percent change in weight? Write down the formula in your lab
notebook.
The following objectives should be included in your lab notebook. They will also help you
write the “results” section of your lab report.
19. Briefly (a paragraph) describe how the experiment was carried out.
20. Record your data in table form in your notebook.
21. Graph your data by hand or by using a spread sheet (should use a spreadsheet generated
graph for your lab report). Be sure you also include a graph of your data in your lab report. (See
lab Study B, p.16 - 17 of your lab manual for graphing suggestions).
22. Describe whether each of your potato cylinders gained, weight, lost weight or remained the
same weight.
23. Calculate the percent change in weight for each potato cylinder.
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BIOL 1107L
Diffusion and Osmosis
24. Compare each of your potato cylinders using percent change in weight.
The following objectives should be included in your lab notebook. They will also help you
write the “discussion” section of your lab report.
25. What does it mean if the potato gains weight, loses weight, or remains the same weight?
26. If your potato gains weight, is it in a hypertonic, hypotonic, or isotonic solution?
27. If your potato loses weight, is it in a hypertonic, hypotonic, or isotonic solution?
28. If your potato’s weight does not change, does that mean it is in a hypertonic, hypotonic, or
isotonic solution?
29. If a solution is isotonic to your potato cylinder, how does the concentration of the solution
compare to the concentration inside your potato cylinder? Use this information to estimate the
osmolarity of your potato.
30. Write a conclusion statement and state whether the hypothesis was supported or rejected.
Date should be provided to support you statement.
31. Were any of your results unexpected? What are some possible explanations for the
unexpected results?
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