This is a table of my results:
Form looking at my table of results it is clear that something went wrong in my test. The start weight of the potato for the distilled water is less than when it has been in the solution, which is strange, as it should have stayed the same. This could have been due to the potatoes not being dried of properly which I will try and improve in my final test. I would have also expected that the mass of the potatoes in the higher solutions would have been lower and this may have been caused by the potatoes being left in the solutions for a shorter amount of time than what was meant causing the results to be closer together. I will also try and improve this in my final test by leaving the potatoes in the solution for longer than my preliminary test. I will also try and repeat the test 3 times to get an average and clearer results.
Key variables
Key variables should play a big part in this experiment. .
First of all, and most importantly, I will have to get the measurements and the weights of the solutions and the potatoes as exact, and as accurate as possible. I will try and get the measurements of the potatoes as accurate as possible for every single potato, evenly cutting the potato pieces, and making a record of the length to the nearest millimetre. And we will be using a very sensitive balance so that we can get the best readings possible.
One of the most important steps in the fair testing is to make sure that the potato is fully covered by the solution. This is because the potato should fully submerge, by having total contact with the solution.
When using the balance, I will make sure that the balance is reading zero before we put the 3 potatoes on it. This is so that I don’t get a false reading, And after the experiment, I will measure the 3 potatoes that should be as dry as possible, and weigh it the same way, taking the reading to the nearest 2 decimal places.
Another important factor of a fair test is to start and stop the clock as quickly as possible. This meaning that I should start the clock as soon as the potato is put inside the test tube, and stop the clock as soon as 20 minutes have passed. Stopping the clock, taking them out and measuring it all in less than a minute will be tricky so I will have to work as fast as possible to get the best results. And there are obviously too many sets to go through at such a fast time. Therefore, we will try our best to weigh the potatoes as quickly and as safely as we can.
Getting and experimenting with the exact measurements of molars and water is vital to this task. If the volume of one solution in a test tube is higher or lower than another this will affect the pattern of results later on.
I will also make sure that the potato is fully covered by the 6 different kinds of solutions. This is because, is the potato isn’t covered up by the solutions, the effect of osmosis might not occur as well as it could do.
Small things such as a dirty test tube, and a slightly cracked measuring cylinder could still affect the results, and therefore I will take these into account as well.
Actual Method
First I will have to get the pieces of potatoes ready. I will push the cork borer through the potato, cutting it into long cylinders with a diameter of 6mm. And then I will cut the potatoes into cylinders of 40mm, and weigh 6 sets of 3 potato cylinders. I will have 6 sets because we will have to test the potatoes in 6 different types of solutions: 0.2, 0.4, 0.6, 0.8, 1.0 molar solutions of sucrose, and distilled water.
I will weigh each set and have them ready for us to put into the test tube.
Then we will put the 6 sets of 3 potatoes in the 6 test tube at the same time and start the clock running for 20 minutes.
After the 20 minutes, I will take all of the potatoes out of the test tube, so that the actual osmosis action stops, and I will put the potatoes onto one piece of dry towel, in their own groups. I will then dry them with the tissue paper, in sets of 3, and weigh the potatoes taking in the average reading of the 3 pieces.
I will repeat the experiment three times so that we can make sure that all our results are similar, and so that we will be able to take the average of the 3 experiments. This makes sure that I get accurate results. Repeating the experiments are important, because we will be able to receive valid results, and look for any anomalous results.
Safety
Safety is an important aspect in every experiment, even if the experiment seems to be very harmless. And that is why we take this into consideration, no matter what.
We will be using a very sharp borer, which could injure someone if it’s not handled properly. And we will also be careful that the solutions don’t get into our bodies internally as just in case, because we are not fully aware of the damage it could do to us. We will also have to take into consideration any spillage’s that occur as this may cause injury if another person slips in the liquid.
Analysing
From looking at my graph it is clear to see that the trend of results clearly fits my prediction. This is easy to see as the stronger the solution the more osmosis occurs. This is because the water in the potato is passing through the partially permeable membrane in order to move from its area of high concentration to the area of low concentration, and is in effect trying to even out the concentration on either side of the membrane. This would happen more in a thicker solution as the water is trying to dilute the solution more as it is a lot thicker and the solutions are more uneven on the sides of the membrane. This is shown in the percentage change on my graph and table , 0.0=%0, 0.2=%2, 0.4=%6, 0.6=%16, 0.8=%18, 1.0=%20.
This proves that more osmosis occurred in the higher concentration of sugar. The jump between the 0.4 and 0.6 results may have been due to the fact the it was left in the solution longer than the others or the remaining water was not cleaned up properly after the potatoes were taken out of the solution. This 1 anomalous result does not affect my test as it still proves my prediction it has just jumped a bit further than expected and could even prove my prediction further.
Evaluation
I followed the plan correctly, I think that I gained accurate and sufficient enough results to conclude the experiment, and to prove my prediction.
My final results were very reliable, due to the precautions I took to make this a fair test.
To make this experiment better, I believe that we could have done one test at a time, so that I could reduce the time difference, when I had to move the potato from the test tube to the balance. Between this, I had to dry the potatoes just enough, and then put them on the scales. When I am doing this for one set, writing down the results at the same time, while the other 5 sets are on the tissue paper, the water outside the potato tissue is going to vary for all. Therefore, I would be able to concentrate more on one of the sets, instead of trying to finish all of them as quickly as we can.
We also could have got more people to do the experiment with us, so that I could organise the experiment better Using more types of solutions would have helped me obtain better results, and more accurate results, so that we can make sure the results are totally correct.
Experimenting with one set for a longer period of time, for each set, would give me better results, because the osmosis action would reach its maximum capability, and therefore tell me how much water could be transferred for each solution.
Repeating the same tasks many other times could have improved the results although this would have been time consuming. The results that I did get backed up my predictions and proved my theory.
My conclusion to this experiment is that the amount of sugar solution in the water greatly affects the amount of osmosis that goes on in plants, where the higher the amount of solution the more osmosis occurs. This would affect the plant as it gives it more turgidity and helps to stabilise it.
