Investigating the Factors Which Affect Osmosis
The aim for this Biology coursework is to investigate hoe the
concentration of sodium chloride will affect the mass of potato chips
that will be the same length and have same width. The time factor for
the chips will be the same to make it a fair test. The main variables
throughout the investigation will be the mass, the length and the
concentration in which the chips are kept in.
Scientific knowledge of osmosis
Osmosis is the movement of water particles across a semi permeable
membrane, from a dilute solution to a more concentrated solution,
until equilibrium is established, i.e. the same number of water
particles on either side of the membrane.
As the potato cell contains a more dilute solution. Water will pass
into the solution to try and balance both things out. If the salt
solution inside the vacuoles of the potato cell is less dilute than
the solution in which it is planted in, water will enter the cell
vacuoles in which the chips will gain mass and length.
How ever, as the osmotic pressure builds up inside the vacuoles less
water molecules will pass into it. Again when the osmotic pressure
inside the vacuoles is the same as the water pressure outside there
will be the same number of water molecules entering and leaving the
cell. In this case equilibrium is relived.
When placed in the solution water will pass out of the cell as the
more concentrated solution is outside the cell. The longer the chips
stay in the solution the more mass will be lost as much more osmosis
occurs. When the cell has lost as much as water as it can it is said
to be plasmolysed (membr...
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...iet a lot of weight, whereas the chips in
the lower concentration gained weight. I have shown this in my graphs
and my results tables. I think that my results are reliable because
the points on the graph is a straight line so my results must be
accurate.
If I done this experiment again I would improve it by making sure
that the potato chips are the same length. Another way in which I
could improve is that I need to be quicker in measuring and placing
the chips into the solution, I say this because, the chips I put in
first have had a longer time to go through the process of osmosis, and
the chips I weigh after the first ones have an unfair advantage as, as
they have had longer time for osmosis. So I need more than one person
measuring and placing the chips in the solution, so we don’t tamper
with the results.