Lab biology
Lab5 worksheet: Membranes, Diffusion and Osmosis
5 points
1.) An experiment was performed in which chicken eggs were placed in vinegar to dissolve away the hard, outer shell leaving behind the semipermeable inner membrane. This membrane, like other cell membranes, allows water and small molecules to pass through which makes it a good model to study osmosis. The eggs were weighed before the experiment began (initial mass). They were then placed into one of the following salt solutions for 12 hours:
0%
,
4%
,
8%
,
12%
,
16%
or
20%
NaCl. The eggs were removed from the solutions and weighed again at the end of the experiment (final mass). The results of the experiment are shown in the table below. (3 points)
a. Complete the table by filling in the remaining columns.
|
Solution (% NaCl) |
Egg initial mass (g) |
Egg final mass (g) |
Net weight change (final – initial) |
Percent weight change ( x 100) |
| 0% |
60 g |
80 g |
||
| 4% |
62 g |
77 g |
||
| 8% |
70g |
79 g |
||
| 12% |
68 g |
70 g |
||
| 16% |
72 g |
67 g |
||
| 20% |
59 g |
b. What are the independent and dependent variables in this experiment?
c. Graph the data from this experiment in the space below using the correct type of graph and following all of the graphing rules. You can either create your graph by hand using a ruler or in a computer program and paste it below.
d. Which solution(s) in this experiment were hypotonic to the egg? Which solution(s) were hypertonic to the egg? Explain how you know.
e. Use your graph to estimate the concentration of solute in your egg.
2) In Minnesota, the roads are sometimes salted in the winter to melt ice. What does this salt do to the plants on the roadside? Be specific and answer in terms of osmosis! (1 point)
3) When a patient arrives at the hospital in need of IV fluids, they are administered a ‘saline’ solution which is 0.9% NaCl. This solution is isotonic to the patients red blood cells. (1 point)
a) What would happen to the patients red blood cells if they were administered an IV solution that was 0% NaCl? Why?
b) What would happen to the patients red blood cells if they were administered an IV solution that was 5% NaCl? Why?