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The Effect of Salt Concentration on Osmosis in Potato Cells

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Title: The Effect of Salt Concentration on Osmosis in Potato Cells Introduction The purpose of this experiment was to observe the effect of various concentrations of water and salt solutions on osmosis of potato cells. Osmosis is the movement of water through a semi-permeable membrane separating solution of a different concentrations. Water molecules follow a concentration gradient; that is, a net movement from where they are more concentrated to where they are less concentrated. Question What will happen to the cell membrane of potatoes if they are exposed to various salt concentrations? Hypothesis The following is the predicted outcome of the experiment: The potatoes in the higher salt concentration will shrink. The concentration of water outside the potatoes has a high salt concentration. The water inside the potatoes will permeate the cell membrane and potato cell will shrivel which is known as hypotonic. The potatoes in the lower salt concentration will expand. ...read more.


2 pieces of potato were placed into each of the 4 glasses for 8 hours. The potatoes were removed from each glass and patted dry with a paper towel. The labels from the glasses were removed and placed by the potatoes to identify each set of potatoes The potatoes were measured and averaged for each set. The variable in this experiment is the water/salt content of the solution. The assumptions are that time, water temperature and surface area are constant. Results The findings were that where the salt concentration in the solution was high, the volume of the potato sample declined; that is, the potato sample shrank in size. Where the salt concentration was lowest, the volume of the potato increased; that is, the potato swelled. The results are summarized as follows: 0% Solution 1.75% Solution 3.5% Solution 7% Solution Beginning Average Volume 4000 Cubic CM 4000 Cubic CM 4000 Cubic CM 4000 Cubic CM Ending Average Volume 5203 Cubic CM 3528 Cubic CM 2957 Cubic ...read more.


There is a movement of water from the cell causes the shrinking. The 0% solution was hypotonic and the 1.75%, 3.5% and 7% solutions were hypertonic. An incidence of isotonic was not displayed. The hypothesis prediction made prior to the experiment were correct except that an isotonic state was not found. The results could have been impacted by the accuracy in the size of the potato samples. Additionally, the measurement of the potato samples after the experiment was conducted were not exact, the volume calculations could be effected. The water temperature also could have an impact as the salt must dissolve in the solution. In a research study to purchase a water filter, knowing about osmosis would be helpful. Understanding osmosis helped me to understand process of reverse osmosis which basically is osmosis with pressure. In reverse osmosis, the membrane is used to form a very fine filter. The water is put on one side of the membrane and pressure is applied to stop, and then reverse, the osmotic process. It generally takes a lot of pressure and is fairly slow, but it works. ...read more.

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Response to the question

This essay is excellent in investigating the effect of salt concentration on osmosis in potato cells in that it introduces the investigation, provides relevant background information, lists out clear and simple procedures, presents the data collected in a coherent manner ...

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Response to the question

This essay is excellent in investigating the effect of salt concentration on osmosis in potato cells in that it introduces the investigation, provides relevant background information, lists out clear and simple procedures, presents the data collected in a coherent manner and even justifies conclusions using data collected in a insightful manner. The essay introduces the aim of experiment clearly at the beginning and crafts the procedure to test this aim. The writer provides an elaborate hypothesis, detailing 3 different outcomes and justifies these outcomes using relevant scientific theory. The materials and apparatus section actually not just lists equipment used but also mentions other details such as quality, quantity, concentration and other details where relevant. Coupled with very simple procedures, the report also presents data very neatly and coherently. In the conclusion, the writer follows up on the data collected to conclude, justifying each conclusion with data. In the end, the writer actually provides real-life applications of the theory employed in the report. However, one note of improvement could be to include the concept of independent, dependent and control variables.

Level of analysis

The report definitely exceeds expectations in several aspects of analysis but also needs more improvement in other aspects. For example, the investigating question needs more improvement as it is rather inaccurate and blur in focus, simply asking “what will happen…” which could be put forward in a more scientific manner as “what is the effect of…” as mentioned by the writer in the title itself. However, the hypothesis section is very well done and can score well among markers as the writer elaborates on each situation that might arise instead of just listing them. All tables show data with consistent number of decimal values, the correct units, proper headings so the report scores on data presentation as well, but to improve the uncertainties of instruments can be indicate. One shortcoming of the report is its lack of depth in the evaluation section. The report discusses the data but could also analyse the trends and other technical details of the data. The report suggests a minor improvement to the experimental procedure but more of such improvements could have been suggested. The writer also does well in extending the report to real-life application, which is commendable.

Quality of writing

The whole report has an excellent presentation. There are very few grammar or spelling errors but even these are not glaring errors. The use of technical terms is adequate and the report explains the biology behind the whole report, detailing the theory on osmosis very well. The report could perhaps be improved by defining the technical terms to a greater extent.

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Reviewed by Arcturus 14/03/2012

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