How Does Distilled Water Affect The Molarity Of Epidermal Cells
OSMOTIC POTENTIAL OF CELL SAP OF PLANT EPIDERMAL CELLS
Aim: The purpose of this experiment is to investigate the effects that the molarity of the sucrose solution and distilled water have on the plasmolisys of epidermal cells of a red onion.
Hypothesis: Taking in consideration osmosis, and my knowledge about it, my prediction is that as the molarity of the solution under which the cells are exposed will increase, also the amount of plasmolysed cells, counted from amount of undamaged cells taken into account, will also increase. Hence, theoretically, the amount of plasmolysed cells in distilled water should be 0, while at 1mol solution, all of the relevant cells should be plasmolysed.
This is so, because plasmolisys occurs due to loss of water through osmosis, which depends on the concentration difference, and consists in the movement from a high to a low concentration gradient. This suggests that on a high molarity, the amount of water present outside the cell is lower than inside the cell, therefore it will move out of the cell, causing a loss of water. There are also other substances which might diffuse out or in, but water is the most relevant one for the sake of this lab work. …show more content…
Variables: independent- molarity of substance dependent- percentage of plasmolyzed cells controlled- same type of epidermal cells, same method
Materials: microsope, razor blade, petri dish, 7 tubes with stoppers, distilled water, sucrose solution, red onion.
Method: (see appendix)
CHANGES: - we used distilled water, hence 7 tubes, and two more pieces of
epidermis
The data was recorded with a table, and for each of the different solutions, only one measurement was made, due to limited amount of time.
Hence, my own data will be grouped with my classmates', in order to achieve more reliable and precise results.
Raw Data:
Amount of Plasmolyzed cells counted from amount taken into account, under solutions with different molarity.
MY RESULTS
My classmates'
[pic]
[pic]
Processed Data:
Average percent of plasmolysed cells out of total amount of undamaged cells taken into account
[pic]
[pic]
Data Analysis and Conclusion
From the data obtained, I am able to say that my initial hypothesis was correct, as in the percentage of plasmolysed epidermal cells of a red onion increased when the concentration/molarity of the solution in which they were conserved for some time, increased. This occured, because, when the cells are placed for some time in a very high sucrose concentration, the concentration of the water inside the cell is higher than out of the cell, hence by the principles of osmosis, which imply that the movement of a substances happens from a higher to a lower concentration gradient, the water inside the cell moved out, into the solution, causing so, a shrinking effect, making the cell hypertonic through plasmolysis.
The graph I obtained from the calculated average of mine and my classmates’ results, is quite clear and does to a certain extent, show the aim of the experiment. In order to do so, however, it was necessary to draw a line through the original results’ line, to emphasize the pattern.
There were certainly mistaked that were made during the lab. My results, were not as precise as I expected them to be. The most obvious example is that at 1mol concentration, I did not have a 100% of plasmolysed cells. It is much probably not a systematic mistake, as I used the same method as my classmates’ did and I did follow it stricktly. Most probably the mistake (mine, and also some that occured, and are visible in my classmates’ data) took place during the counting of the plasmolysed cells under the microsope. In some cases, the number of cells was very high, and it was quite hard to indentify and count correctly all of the undamaged/plasmolysed cells. Another mistake might have been not leaving the epidermal cells in the solution long enough, which was not however, my case. Hence I think that the major and only relevant source of error was the former.
In order to improve my results, next time, I suggest to base my data collection on a smaller amount of cells. Meaning, to only count about 30-50 undamaged cells, and in that scope also the once that are plasmolysed. In such a way, it will be easier to be more precise, easier to count, and our eyes will get less tired. Also, due to time restrictment,there was not enough time to repeat the experiment more times or to make more measurements, causing the possibility of error to higher, and precision to lower.
Aim: The purpose of this experiment is to investigate the effects that the molarity of the sucrose solution and distilled water have on the plasmolisys of epidermal cells of a red onion.
Hypothesis: Taking in consideration osmosis, and my knowledge about it, my prediction is that as the molarity of the solution under which the cells are exposed will increase, also the amount of plasmolysed cells, counted from amount of undamaged cells taken into account, will also increase. Hence, theoretically, the amount of plasmolysed cells in distilled water should be 0, while at 1mol solution, all of the relevant cells should be plasmolysed.
This is so, because plasmolisys occurs due to loss of water through osmosis, which depends on the concentration difference, and consists in the movement from a high to a low concentration gradient. This suggests that on a high molarity, the amount of water present outside the cell is lower than inside the cell, therefore it will move out of the cell, causing a loss of water. There are also other substances which might diffuse out or in, but water is the most relevant one for the sake of this lab work. …show more content…
Variables: independent- molarity of substance dependent- percentage of plasmolyzed cells controlled- same type of epidermal cells, same method
Materials: microsope, razor blade, petri dish, 7 tubes with stoppers, distilled water, sucrose solution, red onion.
Method: (see appendix)
CHANGES: - we used distilled water, hence 7 tubes, and two more pieces of
epidermis
The data was recorded with a table, and for each of the different solutions, only one measurement was made, due to limited amount of time.
Hence, my own data will be grouped with my classmates', in order to achieve more reliable and precise results.
Raw Data:
Amount of Plasmolyzed cells counted from amount taken into account, under solutions with different molarity.
MY RESULTS
My classmates'
[pic]
[pic]
Processed Data:
Average percent of plasmolysed cells out of total amount of undamaged cells taken into account
[pic]
[pic]
Data Analysis and Conclusion
From the data obtained, I am able to say that my initial hypothesis was correct, as in the percentage of plasmolysed epidermal cells of a red onion increased when the concentration/molarity of the solution in which they were conserved for some time, increased. This occured, because, when the cells are placed for some time in a very high sucrose concentration, the concentration of the water inside the cell is higher than out of the cell, hence by the principles of osmosis, which imply that the movement of a substances happens from a higher to a lower concentration gradient, the water inside the cell moved out, into the solution, causing so, a shrinking effect, making the cell hypertonic through plasmolysis.
The graph I obtained from the calculated average of mine and my classmates’ results, is quite clear and does to a certain extent, show the aim of the experiment. In order to do so, however, it was necessary to draw a line through the original results’ line, to emphasize the pattern.
There were certainly mistaked that were made during the lab. My results, were not as precise as I expected them to be. The most obvious example is that at 1mol concentration, I did not have a 100% of plasmolysed cells. It is much probably not a systematic mistake, as I used the same method as my classmates’ did and I did follow it stricktly. Most probably the mistake (mine, and also some that occured, and are visible in my classmates’ data) took place during the counting of the plasmolysed cells under the microsope. In some cases, the number of cells was very high, and it was quite hard to indentify and count correctly all of the undamaged/plasmolysed cells. Another mistake might have been not leaving the epidermal cells in the solution long enough, which was not however, my case. Hence I think that the major and only relevant source of error was the former.
In order to improve my results, next time, I suggest to base my data collection on a smaller amount of cells. Meaning, to only count about 30-50 undamaged cells, and in that scope also the once that are plasmolysed. In such a way, it will be easier to be more precise, easier to count, and our eyes will get less tired. Also, due to time restrictment,there was not enough time to repeat the experiment more times or to make more measurements, causing the possibility of error to higher, and precision to lower.