Apparatus
1 potato borer
3 average sized potatoes
6 Petri dishes
Sucrose solution: 35%, 25%, 15%, 10%, 5%, 0%
Weighing scales
Weighing boat
Knife
Measurements
For this experiment I have decided to make all of the potato tubes 2 grams in weight and 3.6cm long. If my tubes are all the same it will make it easier to collect my results and to plot them on a graph to show increase or decrease.
I think my practical will prove to be a fair test. To make sure it is a fair test all the potato tubes will be left for the same amount of time and all be the same weight and length.
Prediction
I think that this experiment will show that the potato tubes in the stronger solution will shrink and become flaccid and the ones in the weakest solution will become flaccid and they will grow/expand. I think this because in osmosis the potato is trying to make the sugar concentrations in each part equal. Osmosis is defined as the movement of water across a semi-permeable membrane from a region of low sugar concentration to a region of high sugar concentration. As the sugar concentration in the potato will be high against the 0% in the petri dish. This means that the water will move from the petri dish and into the potato. This is caused by the potato attempting to make the concentrations even.
Trail investigation
I think our trial investigation went well. We produced and good set of results and they matched with what I thought it was going to be like. I think the result were measured as accurately as possible and I think we took enough readings for the first experiment. The range of reading is suitable for this experiment. I think in the next investigation we will measure two potato tubes so we can get a more reliable set of results. The amounts of potato were adequate and we have recorded the results in a way that is easy to understand.
Obtaining Results
Apparatus
1 potato borer
3 average sized potatoes
6 Petri dishes
Sucrose solution: 35%, 25%, 15%, 10%, 5%, 0%
Weighing scales
Weighing boat
Knife
Diagram
Method
- Get out all the equipment ready for the experiment.
- Take the potato and using the borer cut a tube out of the middle of the potato.
- Cut this potato down until it weighs 2g and is 3.6 cm long (don’t forget to pat it dry).
- Repeat the third step until you have enough to fill 6 petri dishes with two potato tubes each.
- When the potato tubes are cut, get the sucrose solution and measure 50 ml of each into different petri dishes.
- Place two potato tubes in each petri dish with the solution.
- Place the dishes in a tray and leave them for 24 hours.
- When 24 hours has passed take the tubes out of the solution.
- Pat them dry and weight each one and place the results in the table.
Analysing evidence and drawing conclusions
Conclusion
I conclude that as the concentration of sugar solution goes down, the weight change increases in the potato tubes. This conclusion backs up my original prediction that says that the weight of a potato tube should decrease when the sugar solution is higher and increase when the sugar solution is at its lowest.
Evaluation
The results that we got were similar to each other and overall I think they were reliable. We did not get any really odd results and we did not get any that were obviously inaccurate. I think if we were to want a more reliable conclusion we would have to repeat the experiment a few more times to make sure that our results were typical. I think our method suited our investigation well however we could have changed a few aspects such as testing whether the temperature or the amount of light affected the results. If we were to extend the investigation, we would have to test other variables such as these to develop a wider understanding and so make our conclusion more reliable.
