Investigation of Water Potential of Potato Tuber Cells

Investigation of Water Potential of Potato Tuber Cells

Introduction

This experiment is to find out the water potential of potato cells.

Water potential is the ability of water to move and is represented by

the Greek letter ψ (pronounced “sy”). It tells us which way water will

move and how fast. Water potential is always measured as a negative

number; this is because the water potential of pure water at

atmospheric pressure is zero therefore the stronger a solution is the

more negative the number. This is because a solution has solutes

present and solute molecules slow the movement of the water molecules,

therefore always making the water potential of a solution less than

zero.

The stronger the concentration the slower the movement of water

molecules present due to more bonds between the solutes and the water

molecules, therefore the more negative the water potential. The unit

for water potential is kPa because itÂ’s the measurement of pressure

acting on the water molecules.

There are two factors that influence water potential;

* The concentration of solutes inside the cell

* The pressure exerted on the cell contents by the stretched call

surface membrane or cell wall.

Results Table

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Concentration Mass before Mass after Change in 0 (distilled

(m) (g) (g) Mass(g) water)

1.32 1.47 0.15 0.2 1.35

1.36 0.01 0.4 1.24 1.16

-0.08 0.6 1.38 1.05 -0.33

0.8 1.57 1.