If a plant cell is placed in a solution that causes it to lose water by Osmosis then it will become flaccid. This is the opposite of Turgid. It is when the plant cells membrane and cytoplasm shrinks away from the cell wall, which stays roughly the same shape, but is somewhat weaker, causing floppiness.
Turgid Cell Flaccid Cell
Animal cells, however, can be quite different to plant cells, as they do not have cell walls. In solutions that would cause them to keep gaining water by Osmosis, they swell up and burst as they do not have a cell wall to protect them, this means that they cannot become Turgid. In a solution that causes the cell to lose water by Osmosis the whole cell shrinks, causing size change as well as mass change. This is a problem because animal cells must be kept in a state with the solution outside of the cells must have the same Osmotic strength as the cytoplasm of the cell.
In the body, kidneys provide this environment by monitoring the exact amount of water and salt in the blood stream (among other things). If the kidney were to stop functioning properly then it would cause our cell serious damage.
In this experiment potato cells will be used, this is because the cells are plant cells, and will not burst when placed into distilled water, the cells are not connected to any seriously needed life source, and can go on living longer than an animal cell. It also is because a chip can be taken from a potato without causing serious harm to a potato, but for some reason a human will object to having a cork borer shoved into their chest.
List of Variables
The variables that I will be measuring are the length and the weight of each chip. They will prove the action of Osmosis by increasing or decreasing in mass or length.
Input Variable
The variable that will be changing during the experiment is the amount of salt (m) in the water with the potato strips. This is what is most likely to prove that the potato strips will change mass due to Osmosis as the salt decreases the amount of water equaling the environment for Osmosis to occur. The amount of salt being used will range from no molars (0m) to 1 molar (1m). This can be seen in the results tables and the table below:
Prediction
My hypothesis is that the potato strips sharing the test tubes with a less amount of salt solution will swell, increasing in mass and length. The potato strip sharing the test tubes with a higher amount of salt solution will shrink, decreasing in mass and length.
Outcome
The measurements that I will be collecting from my experiment will be the change in mass and length. The change in mass proves that the cells have lot water, and the change in length proves that they have become flaccid of turgid.
Apparatus
Method
- ! At no time should the potato be consumed in, or if it has been in the laboratory, it may have picked up unhealthy germs that have previously been worked with !
- !Lab coats should be worn for extra protection !
- Take one test tube rack and place 5 test tubes into it. Label the set of test tubes Test 1.
- Using the measuring cylinder, put the allocated amount of salt solution and water shown in the input variable section of this project into each test tube. Label the test tubes so that they are not to be confused.
- Take a potato and use the cork borer to acquire a strip of potato. Repeat this another 4 times. There should be five chips when finished.
- Cut the chips down to an equal size Using the knife, also use the chopping board as to not scratch any surfaces. In this case, I have used a size of four centimeters per chip.! The chip size should not be to small to produce unreadable results, but should not be so long that it is not totally covered by the mixed solution, as not all of the chip will receive the desired effect, rendering the results invalid!
- Record the length of the chips with a ruler, then the weight with the weighing scales.
- Place one chip into each test tube; place the rack of test tubes into a safe place at room temperature.
- Repeat the process a second time, but labeling the set of test tubes Set 2.
Results
Here are the measurements for the chips before they were put into the solutions. The chips have been cut to exactly the same size, and are very nearly the same weight. The averages of size and weight are on the right hand side of the table.
After 24 hours, the results of the test were recorded:
After the average length and weight have been recorded before and after the experiment, it is made possible to calculate the difference in mass and the difference in length. It is also known as Percent change in mass, it shows whether or not the potato really did lose or gain water
Mass
Length
These results show that the Percent change in mass and length decrease as a higher amount of salt is added to the solution; however, it would be easier to recognize and appreciate this decrease by plotting the points onto a line graph.
Conclusion
The results from the experiment show that in the test tubes with the majority of water, the potato chip inside them swelled, and the potato chips inside the test tubes with the majority of salt solution in them shrunk. In the balanced test tube (Distilled water and Salt solution are the same quantity), there was very little change in the mass and length of the chip. This proves my Hypothesis correct, and is a very good example of the action of Osmosis.
Evaluation
The experiment went very well, and according to plan, I proved all of the things that the experiment was produced for. However, there are a few things that I did not feel were completely acceptable, and would have changed if I now had the chance.
One of these things was the range of solutions that I used. Using only five, I did not feel that the results were 100% accurate. I would have preferred to do about 10 to be completely accurate.
I would have also have liked to talk more on the subject of previous experiments that I have done, to give a complete understanding of Osmosis.