Investigation the Water Potential of a Root Vegetable

Investigation to Find the Water Potential of a Root Vegetable

Introduction

Water potential is the tendency of water molecules to move from one

place to another. Osmosis is the movement of water molecules from a

region of higher water potential to a region of lower water potential

through a partially permeable membrane. I will be investigating the

water potential of a carrot to find out at what concentration of salt

solution (molar dm-3) equilibrium can be sustained between the net

movement of water molecules in to the carrot cells, and the net

movement of water molecules out of the cells, therefore finding out

the water potential of the carrot, and at what concentration of salt

solution the movement of water molecules ceases, and what

concentration the water is at inside the carrots cells. I will need to

include and explain the relevant AS knowledge demonstrated by this

investigation. This includes ideas about osmosis, explaining also how

this can affect the structure of plant cells, and showing extremes

such as plasmolysis.

Sill P - Planning

Prediction

I predict that as the concentration of salt solution (molar dm-3) is

increased, meaning that the water potential outside the carrot

decreases, the water potential inside the carrot will decrease. As the

water potential outside of the carrot cell is decreased, the water

potential inside the carrot will increase, when the salt solution is

more dilute. This change in water potential will occur because of a

net movement of water molecules called osmosis.

Osmosis is; The movement of water molecules from an area of high water

potential to an area of low water potential, down the concentration

gradient, across a partially permeable membrane.

A partially permeable membrane, which is found in plant cells, such as

the ones in a carrot, is a membrane that only allows certain molecules

to pass through it, in this case, the membrane will allow water

molecules to pass through it, but will not let the salt molecules pass

through. Therefore, I predict that; when the water potential is higher