To investigate the effect of placing pieces of potatoe in a given strength of sucrose solution.Prediction:I predict that, as the solution becomes more concentrated the more the potatoe cells will shrink, as the water

Prediction:

I predict that, as the solution becomes more concentrated the more the potatoe cells will shrink, as the water, of higher concentration inside the potatoe cells, flows down a concentration gradient into the solution, which has a lower concentration of water molecules.

Variables Description: Constant Variables:

These stay the same all the way through the experiment and are the fair test rules. In this experiment they are that the amount of sucrose solution used must always me 40.0ml. This is to be placed into the Petri dish. The solution needs to always be at the same temperature. I will make sure that all experiments are at 20 degrees centigrade before I start the experiment. I also need to make sure that the potatoe is left in the sucrose solution for the same time, 30 minutes.

Equipment:

• Potatoe
• Sucrose Solution (Strengths of 0.2M, 0.4M, 0.6M and 0.8M)
• Measuring Cylinders
• Petri dish
• Cutting Board
• Scales accurate to 2.d.p
• Stop Watch
• A knife
• 10 pieces of potatoe the same size

Method:

1. I will cut out ten pieces potatoe with a knife.
2. I will label five of the potatoes “1” and the other 5 “2”
3. Using the scales I will weigh the potatoe to 2.d.p. and record the weight.
4. I will fill four measuring cylinders with exactly 40ml of sucrose solution. Each of the four cylinders will have a different strength solution. The solutions I will be using are .2M, .4M, .6M, and .8M. I will fill a fifth cylinder with 40ml of water as a control.
5. At this point I will prepare my stopwatch.
6. The potatoe pieces can now be placed into the Petri dishes and I will then add the solutions of sucrose and the control of water.
7. As the potatoe piece is placed in the Petri dish, the timer should be started. After 30 minutes the potatoe pieces will be removed from the Petri dishes.
8. I will then place the potatoe pieces once again on the scales to see if there is a change in mass.
9. I will record any changes in the weight of the potatoes and create a results table.

   

Results

Average Increase in mass of potatoes in petri dishes 1-5 (g):

1) 0.22
2) 0.02
3) -0.095
4) -0.205
5) 0.435

Percentage change in mass (%):

1) 4.905
2) 0.441
3) -2.021
4) -4.77
5) 10.308

Conclusion

In conclusion to my investigation, when I use 0.4 M level sucrose, the mass reaches an isotonic level – the water and sucrose solution level is equal. When I use 0.2 M strength of sucrose solution, the mass becomes hypertonic – there is more sucrose solution than water. And finally when I use 0.6 M and 0.8 M strength of sucrose solution, the mass become hypotonic.

My prediction was correct, as the strength of the sucrose increases, the more the potatoe cells shrink. This is due to the reasons the water, of higher concentration inside the potatoe cells, flows down a concentration gradient into the solution, which has a lower concentration of water molecules. If I were to do this experiment again, I wouldn’t change anything due to the fact that the experiment was successful and my method worked.

Explain my graph

More conclusion

Evaluation – critisize n change