Investigate the Water Potential of Potato Cells

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Investigate the Water Potential of Potato Cells

Introduction

In my investigation, I hope to determine the water potential of potato

cells. The plant material I will use in my investigation will be

potato chips, which I will cut myself prior to the investigation.

I hope to find the concentration of a solution where the chip stays

the same mass and length, which will tell me that the water potential

inside the cells is the same as the water potential outside the cells.

Background

Osmosis is defined as the movement of water through a semi-permeable

membrane. Semi - permeable membranes are permeable to water but

impermeable to certain dissolved substances. In the case of this

experiment, the sucrose molecules cannot diffuse through the cell

membrane because the sucrose molecules are much bigger than water

molecules.

The water potential of a solution is a measure how dilute the solution

is, and therefore of how readily water will diffuse from this

solution, through a semi-permeable membrane, into another solution.

Pure distilled water has a water potential of zero: the water

potential becomes more negative as more substances are dissolved in

it. When two solutions are separated by a semi-permeable membrane,

water moves from the side with high water potential to the side with

low water potential:

If we dissolve substances in water we lower the water potential of the

solution:-

High water potential Some water potential Low Water Potential

Chip grows Chip stays the same Chip shrinks

Key Variables

o Mass of the chip - I think that the larger the mass of the chip then

the bigger the difference in results will be, therefore I think that

to make experiment more easy it would be best to u...

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...ive

balance to measure the mass, and I could have used a burette or

pipette for volumes of liquids. I also could have used a sharper knife

to cut the lengths of the chips. All of these things would have made

my experiment more accurate. I also could have done a few more

averages and repeats, to decrease the margin of error in my

experiment, making my results more reliable.

For further work, I would like to see if in my experiment I could

actually get the result in my experiment where chip does not change at

all, by putting it in the correct Molarity of sucrose solution. I

would do this by putting it in different concentrations, ranging from

0.1M to 0.4M, and see what happened. I would also like to do the

original experiment again, but using the improvements I listed above,

and see how much of a difference there was in the results with the

improvements.

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