Osmosis Investigation

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Osmosis Investigation

How different concentrations of sucrose solution effect potato tissue.

Aim

How do different concentrations of sucrose solution effect potato

tissue.

Background Information

Osmosis is the movement of water molecules though a partially

permeable membrane from an area of high water potential to an area of

low water potential.

High Concentration

Low Concentration

The membrane lets small water molecules pass though but not large

ones.

The flow continues until the concentration becomes the same on the

inside as on the outside. This is called equilibrium.

Molarity is a measure of concentration.

Prediction

I predict that the potato will change in mass and in length. I believe

this because each Molarity of sucrose will change the potato's water

content. This will happen because either the concentration will higher

in the sucrose and lower in the Tubas or lower in the sucrose and

higher in the Tubers. Therefore water will travel in or out of the

potatoes cell though its partial permeable membrane.

Preliminary Method

· I will firstly get 10 test tubes and to test tube racks

· Then I will cut 9 pieces of potato

· I will then get 3 different Concentrations of sucrose solution and

add 20cm3 to each test tube

· Cut a 4 mm in diameter tuba to 1 cm in length

· Now I will measure the length and mass

· Now place the pieces in

· Now leave this for 15 minutes

· Now I will measure the length and mass

Preliminary Results

After we did the Preliminary Test we decided to use 1 cm long 4 mm

diameter tubas. We would put them in 25 cm3 sucrose solutions. I don't

have any actual results because the potato tubas shrivelled up in the

fridge.

Method

1. I took two average sized ground potatoes and checked that they were

both healthy and hard.

2. Using a standard kitchen knife I peeled the potatoes and used a

potato tuba to cut 18 equally size tubas

3. Using a scalpel and ruler I cut the potato into lengths of 4mm by

10mm. I had to be very careful whilst cutting the potato as the

scalpel is exceptionally sharp. I then had 18 tubas

4. Taking a test tube rack I placed 18 test tubes in it and then

labelled them (0.00M, 0.25M, 0.50M, 1.00M, 1.50M, 2.00M)

5. Using a measuring cylinder I measured out 25cm3. I then poured this

carefully into ea...

... middle of paper ...

...the water potential inside the tissue.

To measure the tubers I think I would use a digital measurer that goes

to two decimal places for accuracy and it would go to the same

accuracy level as the top pan balance.

I would also increase the amount molar amounts I use, such as 0.25 and

0.75. one explanation for the bad results is when the potato chips

were removed from the test tubes and dried I may well have dried some

potatoes more thoroughly than others and so some would have more

excess water, which would add to the mass. If the experiment was

repeated I could find another way to dry the potatoes that would

ensure that all were dried in the same way for the same time. I were

to repeat the experiment I would have possibly found a machine to cut

the potato as it would ensure that all potatoes would be the same

weight and dimensions. As well as the potato I could have found a more

accurate way to measure out the solutions and to determine the molar

concentrations. Perhaps I could have used a burette. This would ensure

that I have an accurate amount of fluid in each test tube. I could

also weigh each tuber on a more accurate scale, e.g. not to 0.00g but

to 0.0000g

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