Title: Measuring the Efficiency of Diffusion In Agar Cubes
Question: What does the length of a cube determines the efficiency of diffusion
in cells?use iv and dv in q, hypoth and title
Abstract: In this Experiment, I explored and investigated one of the most
important cellular processes called diffusion. By measuring the distance of
diffusion in agar cubes and transforming the data, I found results that explained
what determined the efficiency of diffusion. The efficiency of diffusion is
determined by the size of a cell in particular its surface area to volume ratio and
was clearly reflected in my results and graphs. Put numerical results, conclusion
and eval here.
Introduction: In this experiment, I explored and measured the efficiency of
diffusion. Diffusion is one of the most important processes of a cell as it is used to
transport materials such as molecules, nutrients, water, oxygen, and cellular
waste through the cell membrane of a cell. In this experiment we used gelatin
blocks called agar cubes to represent the cell, and measured how much distance
Sodium Hydroxide could diffuse in the cube after a set time. Our experiment
investigated the relationship between surface area/volume and efficiency of
diffusion in the model cells. Write something here about why cells are small – the
theory about surface area to volume ratio
Hypothesis: The efficiency of diffusion is determined by a cell’s surface area and
volume. Therefore, materials in a cell that is smaller in size will diffuse much
faster as the distance to the center of a cell that has a smaller volume and surface
area is much shorter than larger cells that have corresponding larger surface
areas and volumes.
Independent Variable: The independent variable in this experiment is the
length or size of the agar cubes.
Dependent Variable: The dependent variable in this experiment is the amount
distance of Sodium Hydroxide that diffuses into the agar cube.
Controls: Our controls were the total time in which the cubes were submerged
in Sodium Hydroxide, the gelatin substance, and the materials used in
conducting the experiments such as the scalpel, ruler, beaker, sodium hydroxide,
phenolphthalein, gelatin etc., and the method for measuring the diffusion.
Materials:

Scalpel

Ruler

Beakers

Spoon/tongs

O.1M Sodium Hydroxide

Indicator: phenolphthalein
Procedure: See attached
Results:
Cube Size
(cm)
Total Cube
Volume
(cm3)
Total
Volume that
was not
pink (cm3)
Total
Volume
that was
pink (cm3)
Percentage
of Diffusion
(%)
Surface
Area of
cube
(cm2)
Surface
Area to
Volume
Ratio
1
2
3
1
8
27
0
1
8
1
7
19
100.00%
87.50%
70.40%
6
24
54
6
3
2
Distance
Travelled
by NaOH
in
diameter
(cm)
0.5
0.5
0.5
Distance NaOH diffused (cm)
Length of Cube vs. Distance NaOH
diffused (cm)
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1
1.5
2
Length of Cube (cm)
2.5
3
3.5
Percentage of Diffusion
Length of Cube vs. Percentage of
Diffusion
120.00%
100.00%
80.00%
60.00%
40.00%
20.00%
0.00%
0
0.5
1
1.5
2
2.5
Length of Cube (cm)
3
3.5
Percentage of Diffusion
Surface Area/Volume Ratio vs.
Percentage of Diffusion
120.00%
100.00%
80.00%
60.00%
40.00%
20.00%
0.00%
0
1
2
3
4
5
Surface Area/Volume Ratio
6
7
Analysis:
Equations and Calculations:

Volume: L x W x H

Volume of Cube Undiffused: (L - (2 x 0.5))3

Volume of Cube Diffused: Total Volume – Volume Undiffused

Percentage of Diffusion: Volume Diffused/ Total Volume x 100

Surface Area = L x W x # of sides

Surface Area/ Volume Ratio
I transformed my raw data, which was the distance the Sodium Hydroxide
diffused, by using all the equations listed above. In doing these calculations I
successfully expanded and elaborated my raw data into data which could be
graphed and further analyzed.
Discussion: The first graph shows that the length of the cube did not affect the
distance diffused by the Sodium Hydroxide as expected. As the length of the cube
increased, the distance of diffusion by the Sodium Hydroxide stayed the same.
The second graph shows that as the length of the cube increases, the percentage
of diffusion decreases, showing a negative correlation. This confirms that as the
efficiency of diffusion decreases as the length of the cube decreases. The third
graph shows that as the surface area to volume ratio increases so does the
percentage of diffusion, showing a positive correlation. This confirms that a
larger surface area to volume ratio leads to more efficient diffusion. Graphs one
and two both show linear relationships while graph three displays a positive
curve.is it an exponential relationship???? What happens as the cube gets even
smaller? Even bigger?
Conclusion: The results of our investigation clearly prove my hypothesis was
correct. I predicted that a decrease in the length of a cube would increase the
efficiency of diffusion, which is clearly depicted by the data table and graphs. The
higher the surface area to volume ratio was in the model cells, the more efficient
its diffusion and vice versa. In conducting this experiment I experienced firsthand how diffusion occurs in cells. I learned that the efficiency of diffusion does
in fact depend on a cell’s size, giving smaller cells great advantages, which
explains their microscopic size.
Evaluation: Our overall procedure was not very effective. The main reason was
that the Agar Cubes’ consistency was very fluid and extremely difficult to work
with. It was extremely difficult to cut reasonably accurate cubes out of the gelatin
mass. The gelatin would melt and break apart with the slightest touch. After
soaking the gelatin in the sodium hydroxide, the gelatin would be even more
fluid and would break apart when trying to get it out of the beaker to measure
the distance of diffusion. The actual measuring was also very difficult as the
gelatin had almost completely melted and had no shape. In conclusion, The
quality of the gelatin caused our data to not be very precise.
Improvements: The only improvement I would make would be to improve the
quality of gelatin. I would add much less water to the gelatin mix so that the
consistency of the gelatin would be much harder and easy to use. This in turn
would streamline our whole procedure and provide very accurate results.
Extensions: Possible extensions would be to collect more data and conduct the
experiment with more varying sizes of cubes. Another extension could be to try
the experiment with different shapes of gelatin to see if it plays a role in the
efficiency of diffusion. Another extension could be to conduct an experiment
investigating Osmosis and Osmotic pressure. A possibility would be to
extrapolate and extend the lines of the graphs to get a better understanding of
my results.maybe use real cells such as onion skin or eggs