Length: 803 words (2.3 double-spaced pages)
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The aim of this experiment is to show how osmosis works in a plant
The ways we will do this experiment is firstly by getting a beaker and
put a 100ml of water in it, then get a visking tube and put it in the
beaker, so we don't block the holes with natural grease on our hands.
After, we will get another beaker and pour some 1% sugar solution in
it. When we have done this, we get one end of the visking tube and
'ruffle' it, then we get some string and one person will tie the end
of the tube, while the other person hold it. The visking tube then
will go back in the water, while we get a dropper and the beaker of
sugar solution. After we will use the dropper to slowly and neatly
pour the 1% sugar solution in the visking tube; we will fill it up ¾
of the way. Then again one person will tie the other end; while the
other person holds the tube, so now we have both end tied- we will
make sure they are no leaks. When we have done this, we will take the
beaker with water and visking tube to a weighing machine; we will then
take the visking tube out and measure the mass of it (in grams).
After, we will put the visking tube back in the beaker and leave it
there for about 20 minutes. When the time is up, we will measure the
mass of the visking tube again (in grams). During the experiment, we
will observe the visking tube during the 20 minutes and see if the
mass has increased or decreased at the end of the experiment.
This experiment could be repeated, but using a 10% sugar solution,
which would have helped us differ the different mass increase or
decrease in both of them. We were planning to do this one to, but
unfortunately-due to fewer supplies of visking tubes we could only
mange to do the 1% sugar solution.
Plan: Fair and Accurate Test
I will make this test fair and accurate by:
* Being careful, so I don't spill any sugar solution in the water.
* Making sure that I keep a record of the time well.
* Making sure conditions of both visking tubes are exactly the same.
* Making sure I use the scale properly.
My prediction is that the mass will increase in the visking tube, as
osmosis will take place and water molecules will move across the
partially permeable membrane of the tube- from the high water
concentration; outside the visking tube to the low water
concentration; inside the visking tube. Also, if we managed to do both
concentrations of sugar solutions- I would have predicted that the 10%
sugar solution visking tube would have increased in mass more than the
1% solution visking tube.
The experiment shows how osmosis works in plant cells as, the visking
tube represents plant cells, which have a partially permeable membrane
and they store glucose-which is a sugar, made from photosynthesis.
Also around the cells water is bought up-to be provided to the cells.
The experiment setup is a bit like the conditions in plants.
The mass increases in the visking tube as osmosis takes place. Osmosis
is the diffusion or movement of water particles through a partially
permeable membrane from a region of high water concentration to a
region of low water concentration. The visking tube has a selectively
partially permeable membrane, -meaning it lets certain particles
through and not others, the water particles can pass through in both
directions, but just like the glucose in plant cells, the sugar
particles can't pass through the membrane, meaning they can't diffuse
so the water particles use osmosis to find the balance of
concentrations. This is why the water particles move from the high
water concentration or a dilute/hypotonic solution, where there is
100% pure water particles to the low water concentration or
concentrated/hypertonic solution, where there is less water particles
as there is some sugar particles, taking up the space. Although the
water particles can move through the membrane in both directions- the
water particles diffuse into the visking tube through the partially
permeable membrane to make a balance in the concentrations of outside
the visking tube and the inside of it, meaning the mass of the visking
tube will increase. When this happens in the cell and tube swells up
and becomes turgid.
My results were:
1% sugar solution
10% sugar solution
The Difference of the 1% sugar solution is: 17.27 - 16.30 = 0.97
The Difference of the 10% sugar solution is: 13.52 - 12.27 =
In conclusion, my predictions were correct. The sugar solution visking
tubes did increase in mass. It did this as the water molecules moved
from a high water concentration to a low water concentration. Osmosis
occurred as the concentrations of inside and outside the visking tube
was unbalanced, also as the sugar particles are too big to fit through
the membrane-which they can't diffuse to balance it out
I think this experiment was very good to show how osmosis work in
plant cells, as the setup showed the conditions well and it proved
good and accurate results. Also, you could see the difference easily
and it helped me understand the theory better. Although it is an
experiment which can easily go wrong and it is tricky to do,
especially tying the string on the tube's ends. I think the results
this experiment produced was fairly accurate, as the prediction did
work and it showed an increase in mass, but I don't think it produces
perfect results, as some liquid could leak. If I was to improve this
experiment in any way, I would try to do the 10% sugar solution
visking tube. Also, I would repeat the experiment more times and try
to record the results over a longer period of time. I would do these
to have more reliable results and I could do more things with them.
Overall, I think this experiment was effective and it helped me
understand osmosis a lot better.