Biology AT1-osmosis in potatoes.

Biology AT1 - Osmosis

Skill area P

Aim

To investigate a factor which might affect the movement of water in and out of cells.

Introduction

Osmosis is the movement of water in and out of cell membranes, which act as semi-permeable membranes. Semi permeable membranes are cells, which only take in a limited amount of a liquid. The water passes from a region of high to a region of low concentration, until the two are equal in concentrations of water.

If a cell is placed in water or a dilute solution than the cell will take in the water and it will swell up. It will increase in size and not burst as this is due to the fact that the cell walls are made from cellulose, which is extremely strong. After a while the cell does not swell and stops increasing in size.

Preliminary Work

For my preliminary work I used a cork borer of 10mm width, to cut three chips from a single potato.

Sodium chloride crystallization at Devil's Golf Co...

Sodium Chloride

Sodium chloride crystallization at Badwater Basin

I got them to be 55mm in length and the average mass of the three chips was about 5.7 grams, also the width of each potato chip was 10mm. I put the potato on a white tile so it didn't damage the table.

To begin with I got three cups. The first one I filled it with 100ml of distilled water, the second, I filled with 50ml of distilled water and 50ml of Sodium Chloride and the third, I filled with 100ml of Sodium Chloride. The concentration of the Sodium Chloride stayed the same in each cup and experiment, which was 1 molar. Also the temperature of each solution was averaged at about 22˚C.

We added the potato chips to the solution and then left the experiment for 15 minutes. When it had...