Name of Lab: Lab 3 – Diffusion and Osmosis

Name:

Section Number

Name of Lab: Lab 3 – Diffusion and Osmosis

Date Completed:

Directions:
·
Fill in
the following fields as completely and accurately as possible. Please be sure to practice appropriate
grammar, punctuation, and spelling.
·
When
finished, save your document with a file name that includes your name, section
number, and the assignment (i.e. RoyMason_Lab3_Sect 3536.doc). Please only send
.doc or .rtf files. Work submitted in any other
format will not be graded.
·
Attach
your Lab 3, in the assignment section of BB, before midnight on the day it is
due. Late work will not be
accepted.
·

Be sure
you are using your own words! Plagiarism in any form will not be tolerated!
If you
are unsure what constitutes plagiarism, consult the most recent college catalog
or ask the Instructor or Teaching Assistants. Labs that are judged to be
plagiarized will receive no credit.

We would like you
to time yourself on these labs to see how long it takes you to work through
them. Please take notice of the time you
start your lab and note it down. When you’re completed write the time lapsed at
the top of your answer sheet. ­In the box provided.

Time:

Fill in the charts
and answer the questions that follow:

Initial Volume in Displacement Cups:
(should be 200 ml) 3 cups filled with 200ml each, 1 for each % solution you
test.

Concentration

Initial
Volume of Tube
(should
be about 25-50 ml)

Volume
of cup After

Change in Volume of cup

25%

50%

100%

1. Which bag (25%, 50%, or 100%) demonstrated the
greatest concentration gradient
(difference in concentration between two areas) when placed in water?

2. Based on your knowledge of osmosis and diffusion,
what did you expect to happen when the bags were placed in water (Develop a
hypothesis for this experiment)? Should the water flow in or out? Should the
molasses flow in or out?

3. Describe
“selectively permeable”. Why is selective permeability such an important
property of our cell membranes?

4. Was the dialysis tubing selectively permeable? Was it permeable at all? What evidence do
you have to support this?

5. Was dynamic equilibrium reached in any of
the molasses demonstrations? Explain your answer.

6. Give some possible sources of error. If you did not get the result you expected,
offer some reasons why—was the experiment flawed? What would you do
differently next time?

7. What comments can you make about what you learned
from this lab? Why are the properties of diffusion and osmosis important to
the study of biology?