Sherman Chen 3B
Biology 1
Mr. Boyer
Osmosis and Diffusion Lab using Potato Cores
Research Question: Will there be a different amount of water moving in or out of a
set of potato cores if they are placed in solutions with different concentrations of
sucrose?
Introduction: Osmosis is the movement of water across cell membrane/cell walls
through protein channels. The water moves due to water potential of the cells,
water moves from an area of high water potential to an area of low water potential.
A greater concentration of solutes inside the cell than outside the cell results in a
low water potential and the water will respond by moving into the cell. If one area
has a great deal of water, it has a high water potential, and if an area has a great deal
of solutes, it has a low water potential. In this lab, we were asked to observe the
change in mass of potato cores when they are put into different concentrations of
sucrose in the solution.
Hypothesis: If the concentration of sucrose in the solutions were higher then there
would be more water moving out of the potato cores.
Variables:
Independent Variable – Concentration of sucrose in solutions
Dependent Variable – Mass of the set of potato cores (Movement of water in or out
of the potato cores)
Controlled Variables – Number of potato cores in one set; Length of potato cores;
Amount of solution
Materials:
 Potato cores (4 per condition)
 Sucrose solutions (.2, .4, .6, .8, 1.0)
 Distilled water
 Electronic balance
 Plastic weighing tray
 Plastic cups (6)
 Graduated cylinder (50 ml)
 Scalpel
 Marking tape
 Blue tweezers
Procedures:
 Using marking tape, label 6 cups with the following solution types (.2, .4, .6,
.8, 1.0 and Di water)
 Place approximately 50 ml of the various solutions, each cup receiving a
separate solution. Suggestion, measure the di water with the graduated
cylinder, and fill the other cups to the same level
Sherman Chen 3B
Biology 1
Mr. Boyer
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Obtain 24 potato cores and cut them to equal sizes (about 2.5 cm). All the
cores you use must be the same length
Divide your 24 cores into 6 groups and gently blot them dry with a paper
towel
Using the electronic balance
and plastic weighing tray
mass (weigh) each group of
potato cores and record the
data in a table that is labeled
with a detailed title and
which provides the error
measurement of the
electronic scale. MAKE SURE
TO TARE THE TRAY. The
table should record the type
of solution in the cup and the mass of the potatoes in the cup.
Place the potato core sets in their appropriate cup and place in Mr. Boyer’s
back prep room in the fume hood that is labeled with your block (3B or 4B).
PS make sure to indicate on your cup your group number, Mr. Boyer will
assign group numbers during the lab
24 hours later (app) you will need to come and measure the mass of your
potato cores. To do this you must pore off the fluid in the cup and use the
plastic blue tweezers remove the cores, blot them dry just as you did in the
set up phase and final measure them using a plastic weighing tray. MAKE
SURE TO TARE THE TRAY. Record your potato group mass on your data
chart.
Finally dump your potato cores in the trash and wash and dry your
equipment (cups, tweezers and return them to their stations
Calculations. For each setup (all 6) you will need to calculate a percent mass
change. To do this you will use the following formula (final mass-initial
mass)/initial mass x 100. You will need to record this data in your data table
as well. Make sure to keep track of the positive and negative changes if they
occur
Data Chart:
Potato Group
0.0
0.2
0.4
0.6
0.8
1.0
Sherman Chen 3B
Biology 1
Mr. Boyer
(Concentration
of sucrose in
solution)
Initial Mass (g) 3.0 
0.05
Final Mass (g) 3.3 
0.05
Percentage
10%
3.0 
0.05
3.2 
0.05
6.67%
3.0 
0.05
2.8 
0.05
-6.67%
3.0 
0.05
2.3 
0.05
-23.33%
3.0 
0.05
2.1 
0.05
-30%
3.0 
0.05
1.7 
0.05
-43.33%
Graph of the Results:
Percentage Change in Mass of Potato
20.00
Percentage Change (%)
10.00
0.00
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-10.00
Percentage Change
-20.00
Linear (Percentage Change)
-30.00
-40.00
-50.00
y = -56.189x + 13.651
Concentration of Sucrose (mol)
Zero: 0.24
Conclusion:
The results we got were expected from our hypothesis. As the concentration of the
sucrose increased, the final mass decreased. All of the potato cores’ initial mass was
Sherman Chen 3B
Biology 1
Mr. Boyer
3.0g and for the first two concentrations of sucrose, 0.0 (distilled water) and 0.2, the
final mass increased; this means that the water moved into the potato cores. For the
other concentrations of sucrose, the final mass all decreased; this means that the
water moved out of the potato cores. My hypothesis was that the higher the
concentration, the more water will move out of the potato cores, and I was right.
This was not hard to predict because if the solution had a higher concentration of
sucrose, it would have a lower water potential meaning that water would flow out of
the potato cores and into the solution. In the graph plotted mass in percentage
change vs. concentration of sucrose in solution, the best-fit line equation is y = 56.189x + 13.651. The line touches the zero on the x-axis at around 0.24; this
number is the water potential for the potato cores because at around a
concentration of 0.24 of sucrose in the solution, the mass of the potato cores does
not change. The water potential number we got was pretty much similar to other
groups except for one where they probably graphed their results wrong. The water
potentials for the other groups were: 0.75, 0.34, 0.22, and 0.37. I think there might
be some differences in the results of the groups because the time we left our potato
cores in the solution were probably all different.
Evaluation/Reflections:
Positives: We were efficient and everybody did their jobs. We got the results we
were expecting. We did not have many problems, the experiment went smoothly.
Negatives: We did not wait exactly 24 hours, nor did we measure how long it was
we waited until we checked the mass again. First we thought we had different
graphs but then I realised I had my concentration of sucrose wrong.
What did I learn: I learnt what osmosis and diffusion was, our experiments generally
showed how it works.
Changes: We could have measured the time we waited in between the two times we
measured the masses of the potato cores. We also could have been more precise
with the measurements like, the length of potato cores and the volume of the
solution.