Osmosis in Potato Cells

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Osmosis in Potato Cells

Plan

Introduction

Given that osmosis is the movement of water molecules by diffusion

from a place where the water molecules are in a higher concentration

(high water potential) to a place where the water molecules are in a

lower concentration (low water potential) through a partially

permeable membrane, the experiment to test osmosis in potato cells was

set up. The experiment would prove the theory of osmosis and determine

whether the concentration of water in the solution surrounding the

potato was higher or lower than that of the water concentration inside

the potato. This would cause the potato to become turgid or

plasmolysed.

Diagram of apparatus

Variables and Method

Above all other factors, for this experiment to work it needed to be a

fair test. For this to be possible, all variables had to be controlled

throughout.

Seven separate concentrations of water and sucrose solutions were used

in this experiment with a maximum of 20% sucrose. These were

distributed accurately with the use of measuring cylinders as the

concentrations of water and sucrose held great sway on the dependant

variables, such as the mass or length of the potato at the end. Each

solution had a volume of 20cm and both the temperature and pH were

recorded.

It was necessary that all seven samples of potato had to be the same

length, width and therefore surface area before the experiment began.

This was so equal amounts of solution could make contact with each

potato and that there was the same amount of water inside each potato

to begin with. For accuracy a cylinder shaped cork borer of size five

was used and once all the samples had been pulled out of the potato a

metal rule marked 5cm of length on the potato and the left over were

cut off with a sharp blade. The mass of each potato was then recorded

to two decimal places using the balance so these could be compared

with the end results.

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