In this case, when the water concentration is lower in the tissue, the water will go inside the tissue of the potato, thus making the potato heavier. By the potato being heavier this makes it longer in length.
If there is a low concentration of both distilled water and sucrose, there really shouldn’t be a visible change in weight of the potato. If there is a higher concentration of water in the potato, then the water will go out of the potato.
Plant cells always have a strong cell wall surrounding them. When they take up water by osmosis they start to swell, but the cell wall prevents them from bursting. Plant cells become turgid when they are put in dilute solutions. Turgid means swollen and hard. The pressure inside the cell rises and eventually the internal pressure of the cell is so high that no more water can enter the cell. This liquid or hydrostatic pressure works against osmosis. Turgidity is very important to plants because this is what make the green parts of the plant "stand up" into the sunlight.
When plant cells are placed in concentrated sugar solutions they lose water by osmosis and they become flaccid. This is the exact opposite of "turgid". The contents of the potato cells shrinks and pulls away from the cell wall. These cells are said to be plasmolysed.
The potato will be cut up into pieces, thus it will need something to survive and in this experiment it will need light and water. Obviously with both of these sources the potato will survive, however it can’t have too much water or too little water. Plus, if the concentration of water is too low in the potato, then the water from the solution will transfer into the potato. This is another example of Osmosis.
So I predict, using all the scientific knowledge that I have gathered on Osmosis that the stronger the concentration of sucrose the shorter the length of the potato. The water in the potato transfers to the sucrose solution, because transfers from a high concentration to a lower concentration.
Fair Test
Fair testing should play an integral part in the experiment. The reason for this is that if I do the investigation unfairly then my results would be unreliable and would lead me to the wrong conclusions.
First of all, I need to get the measurements of the potato chips exact, the reason being is that I will then have to measure the potato after the Osmosis has occurred, thus I need an exact length 2 CM for all of the potato chips. Also it will be vital for the experiment, that all the potatoes have to be covered the sucrose solution.
Safety
Safety is the most important thing in an experiment, even when they may seem harmless. I will be using a sharp knife to cut the potatoes into cylindrical pieces and if I don’t use it properly then I could injure my self or someone else that is around me at the time of use.
Method
I believe that this experiment is very easy to carry out as the core of it is to potato chips in the sucrose solution over around about 24 hours, so that Osmosis can occur between the potato and the sucrose.
I will get five cylindrical pieces by cutting them from a potato, which a cork borer. I will then measure the discs, so they should at 2 CM in length. I decided to cut out 30 potato discs, because I have chosen to repeat each experiment 5 times for me to try and get the best possible results and look for any anomalous results.
I then separate the potatoes in different groups, e.g. sucrose 0.1 mol sucrose, 0.2 mol sucrose, 0.3 mol sucrose etc. Each group will have five potato chips.
Results
In the table above, it shows the concentration of the sucrose as opposed to the length of the potato chip. As you can see, the more concentrated the sucrose solution is the shorter the length of the potato chips. Also I did the preliminary investigation too, the 0.5 solution of sucrose and the distilled water. By doing this, it increases my chances furthermore, because of the extra results. Most importantly I knew that Osmosis had taken place in the 24 hours I had given it to transfer water molecules.
Conclusion
From completing my investigation I conclude that; I followed the plan correctly. I believe that I gained accurate and sufficient results to conclude the experiment and prove my prediction that I did earlier on. Also one might add the precautions I took to make it a fair test helped me to achieve reliable results.
To have made this experiment significantly better, I couldn’t just have tested each solution once, I had to do it at least five times as it will give me concrete results. By doing the tests at least more than three times for each concentration of sucrose would have enable me to make an average test score for the five potato chips. This would give me a near perfect set of results.
However nothing is perfect and my results could have been slightly better. I could have made some certain procedures before doing the investigation.
They maybe small things, but could have a bearing some of the results. These procedures are as followed;
- Checking the mass of each potato chip
- Putting all five of the potato chips in the sucrose solution at the same time.
- Giving all the potato chips the EXACT time for Osmosis to take place.
- Leaving all the potato chips in the sucrose solution for longer than one day, for Osmosis to reach maximum capacity.
- Getting a group of people to the experiment, one to cut the potatoes, one to dry the potatoes after Osmosis has taken place.
All those points can significantly improve my results, as they more or provide a better ground for Osmosis to take place. Checking the mass of the potatoes I feel was one thing I should have defiantly done. When I recorded the length of the third potato chip for the distilled water solution (in my preliminary section). I received an unreliable result, it measured at 2 CM exactly. This means that no Osmosis had taken place at all during the 24 hours allotted. This cannot be possible as some Osmosis should have taken place. I then checked the mass of the potato and found out that it was significantly lighter than the rest of the potatoes. All in all I am reasonably happy with my results; they have backed up my prediction.
