In this experiment we are going to be studying the affects of Osmosis
in Potatoes. Osmosis is the passage of water from a region of high
water concentration through a semi-permeable membrane to a region of
low water concentration.
A semi-permeable membrane is a very a very thin layer of material,
cell membranes are semi-permeable. These will allow some things to
pass through, but will prevent other things from passing through. For
example, cell membranes will allow small molecules such as Oxygen,
water, Carbon Dioxide, Ammonia, Glucose, amino acids, etc. to pass
through. But they will not allow larger molecules such as Sucrose,
Starch, and protein, etc. to pass through.
The water will cross the cell
membrane in both directions, but now more water leaves the cell than
entering it. The Result of this will mean the cell will shrink.
In this experiment I am going to cut 12 potato sections, I am going to
try keeping these roughly the same size and weight. They will be
around 4cm long, and all will have an average weight of 2.74g.
The liquid that the potato sections will be put into will have
different concentrations, but they will all have a volume of 30 cm.
I am going to have 6 different test tubes which will have the same
volumes but different concentrations. These concentrations will be
diluted water, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M.
I started off getting a large potato. Using a cork borough I removed
12 sections of Potato, I used the cork borough on a tile and kept my
hands well away from it so I would not cut myself.
I then cut these sections down using a razor blade on a tile so they
were all 4 cm long; I measured this using a ruler. I used the razor
blade with precaution, taking into account that it was sharp and
making sure I did not cut myself.
After this I weighed each individual section on a weighing machine,
this scale measures down to 0.00g.
I then got 6 test tubes and filled them with different concentrations
of salt solution; each test tube had a 30cm volume of liquid.
The concentrations were ready prepared for us by a lab technician, and
were as follows: distilled water, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M.
After putting these solutions into the test tubes, I put two potato
sections into each of the solutions, and recorded the individual
weights of the potato sections using the weighing machine, and
recorded which individual sections were put into each of the different
solutions, this assured more accurate results.
I will leave the potato sections for...