Determination of the water Potential of cells of bulky tissues by a weighing method

Equipment used

Cork borer

Scalpel

5 test tubes

Test tube rack

Sensitive balance

A square tile

A potato

Method

1. First I collected the test tubes and placed them into the test tube rack.

2. Secondly I used the cork borer to collect a long strand of potato and also I collected a square tile to cut the potato on.

3. Then I started cut different lengths of potato on the tile then I used the sensitive balance to measure the weight of the potato and recorded the measurement down on paper.

4. Once I had weighed it I then placed the each piece of potato into each test tube.

5. Now I could start adding the different molar of sucrose to the test tubes and I labelled each one so I know which test tube had which molarity in.

6. I left the solutions for a good hour and then I weighed out the potato again and recorded it down on paper. I did this with all the pieces of potato and then found out the percentage change in mass with each one.

     

 

   

Analysis

My prediction was right the as the concentration of the sucrose is increased the mass of the potato does go down. This is all to do with water potential, which is the movement of water molecules from a region of high water potential to a region of low water potential. In this experiment the water potential was greater in the solution when there was less concentration of sucrose and more water. I know this because in my table it shows that when the concentration of sucrose was decreased the change in mass also decreased until the potato ended up gaining weight which at this point meant that the solution of water and sucrose had a greater water potential than the potato.

Evaluation

My experiment was fairly accurate and my results seem to be fairly normal. If I was doing the experiment again and had more time I might of done each concentration of sucrose twice or a few times and I would of taken an average of these results. This would be more accurate because something could go wrong if I was only doing each one once like you might use the wrong concentration for one of them. I think I left my experiment long enough for affective osmosis too take place.