The Effect of Different Strength of Salt Solutions on Potato Cells Through Osmosis
An Investigation to find out how different strengths of salt solution
affect potato cells through osmosis.
I aim to investigate the effect of different concentrations of salt
solution on potato cells when osmosis occurs.
I intent to set up this experiment using equally sized cylinders of
potato submerged in salt solutions of different concentrations. I will
then observe the percentage change in mass over a set period of time.
This will show me how much osmosis has occurred.
Scientific Theory of Osmosis
Osmosis is defined as the solvent of any solution being able to pass
through any semi-permeable membrane from a region of high
concentration to a region of low concentration until both solutions
reach a state of equilibrium. This means that water can flow through a
porous material, such as a cell wall or visking tubing, in order to
balance the levels of concentration. The molecules are then randomly
distributed throughout the solution.
Water particles are small and can therefore easily fit through the
material; however, larger particles such as salt or glucose are too
big to fit through the material.
Osmosis has a significant effect on living cells. Animals cells will
burst in pure water because, as the cytoplasm is fairly concentrated,
the water, which is less concentrated, will enter the cell. As the
dissolved substances in the cytoplasm are larger, they cannot escape
so the cell becomes swollen and may burst.
If an animal cell is placed into a more concentrated solution, the
water in the cell will flow out into the more concentrated solution in
order to dilute it. This will cause the cell to shrink.
Plants cells however are very different as they have a cell wall which
is very strong and fully permeable; however plant cells also have a
cell membrane which is only partially permeable.
If a plant cell is placed in pure water, it will not burst because of
its strong cell wall. The cell will still take water in by osmosis, as
in the animal cell. The cytoplasm will press against the cell wall but
it will not burst. A cell like this is said to be turgid. This means
it is firm and tight and will help a plant with no wood to stay
upright and keeps its shape. Plant cells are usually turgid.
Plant cells in a concentrated solution behave very differently. Like
the animal cell, water flows out by osmosis and the cytoplasm and
vacuole will shrink. The cytoplasm stops pushing against the cell wall
and the cell becomes floppy or flaccid. This is what causes plants to
wilt. If the solution is very concentrated, lots of water will diffuse
out causing the cytoplasm to shrink further. Because the cell wall
cannot shrink, the membrane tears away and the cell become...