Experiment Title: Diffusion: Limitation on Cell Size. Surface
Area to Volume
Introduction:
Single celled organisms can survive as they have a large enough surface area to
allow all the oxygen and nutrients they need to diffuse through.
Materials and methods: (Refer to manual)
Results: (Refer to the excel worksheet)
Discussion:
1) What is the relationship between rate of ion exchange and surface to volume?
As the surface-to-volume decreases the rate of ion exchange will also decrease.
They are directly related.
2) Why is it important for a cell to have large surface-to-volume ratio?
If the surface-to-volume ratio is too small then then rate of ion exchange will
decrease, leading to difficulty in the functioning of the cell.
3) Which is more efficient at exchanging materials, a small or a large cell? Explain.
A small cell is more efficient at exchanging materials, since its surface-to-volume
ratio will be higher and when the material enters the cell, it would be evenly
distributed.
4) How does cell growth affect the cell’s surface-to-volume ratio?
As cell growth increases the surface-to-volume ratio decreases.
5) In order for a cell to continue being efficient at exchanging materials, what must it
do to maintain its surface to volume ratio as it grows larger?
It must adapt to a specific shape, such as being wide and thin.
Conclusion:
From the data obtained it can be concluded that there is some relationship
between SA:V and the rate of diffusion. The experiment results seen on the graph
(trend line) show that the bigger is the surface area to volume ratio, the bigger is
the percentage volume of diffusion, so the rate of diffusion of pigment from the
agar cube. Looking at the data we can notice that smaller cubes (of smaller
volume) have bigger SA:V. We can than state that the results of the experiment
have also shown, that the smaller is the cube, the bigger is the rate of diffusion.