Thepurpose of the experiment, which was determining the solute concentration of apotato, was found by observing and measuring the quantitively results of thewater flow from the solution to the potato.
The process observed is calledosmosis, a passive transport method in which water diffuses across a semi-permeablemembrane from an area of a low solute concentration to an area of high soluteconcentration. By doing this, a relation can be formed between the soluteconcentration of the solution and the percent change in mass. This relation canbe used to create a graph that shows the trends of between the two andtherefore, allow a conclusion to be drawn from the data. With the graph (referto figure one), the value of the x-intercept of the line of best fit will be thesucrose concentration, as a zero percent change in mass would tell us thatthere was no net movement of water. Based on the results obtained, the sucroseconcentration of the potato was approximately 0.3113 M.Thisexperiment was meant to emphasize the process of osmosis and the concept ofzero net movement in an isotonic solution. A solution can be declared isotonicwhen there is an equal amount of solute inside and outside of the cell (citation).
This also means that the solution has reached an equilibrium. To further buildupon this concept, reaching an equilibrium would result in the mass of the cellto being the same as before. In the experiment, reaching an equilibrium wouldresult in the mass of the potato being the same before and after submersion in thesolute concentration solutions. Withosmosis, three different results can occur, a hypertonic, hypotonic, andisotonic solution, one of which will yield the concentration of the potato. Withthe results, it would tell you different changes that had happened to the waterand potato during the elapsed time. After the potatoes have been submerged foran elapsed time, a mass increase would indicate that water has moved into thepotato, further revealing that the concentration of the solute of the potato ishigher than that of the solution. This is a hypotonic solution that can beobserved from the graph at solute concentrations of 0.0M and 0.
2M (refer toFigure 1). A mass decrease wouldindicate that water moved to the solution from the potato, revealing that thesolute concentration of the potato is lower than that of the solution. This isa hypertonic solution can be seen in our results graph at concentrations 0.4M,0.6M, 0.8M, and 1.0M (refer to Figure 1). Finally, no change in mass wouldindicate that there was no net movement within the solutions, revealing thatthe solute of the potato to be the same as the solute concentration of thesolution.
The movement of water occurs to maintain a balance on both sides ofthe semi-permeable membrane of the potato (citation). Asthe solute concentration of the potato was determined to be 0.3113 M, this wouldmean that the sucrose concentration solution of this exact molarity, does notmove across the semi-permeable membrane, as equilibrium has already beenachieved.
The solution can be labelled as isotonic, further indicating that therewould not be a change in mass, as there is an equivalent sucrose concentrationon both sides of the membrane of the potato. The data obtained from the experiment yielded a R2value of 0.9647, suggesting the results obtained from the experiment were quiteaccurate and reasonable as the data gathered fits appropriately into therelationship that is formed between the solute concentration of sucrose and thepercent change in mass. The trend found fits into the data that was obtainedduring the procedure, which allows us to acquire our solute concentration ofthe potato by interpolation with little uncertainty.
Basedoff the results of other experiments that were conducted, the results that weregathered were comparable to those of the other experiments as the outcomes wereall in a similar range of concentrations. In “Biology Potato SoluteConcentration Lab,” the results obtained are relatively close to the concentrationof 0.3113M that was retrieved from this experiment (cite krista’s lab). As thevalues of the concentration are similar, this would indicate that the potatosolute concentration of the experiment is accurate and reasonable. Theexperiment generated reasonable and valid results, making this experiment asuccess, however, there are limitations and sources of error that need to betaken into consideration. There were some limitations regarding the equipmentused, as with the electronic balances and measuring apparatuses, they can onlymeasure to a certain degree of accuracy that may have resulted in a minordeviation when calculating the percent change in mass. Another factor that mayhave effected our end results were the use of two different potatoes during theexperiment. During the experiment, there was an insufficient amount of areathat could be bored in a single potato enough for three trials of eachconcentration solution, therefore, another potato was needed to create enoughpieces for multiple trials of the experiment.
Although this may have resulted invariations in the results, it was necessary to have multiple trials to increasethe accuracy of the overall experiment. Despitethere being multiple limitations and sources for error, they had such little effecton the overall procedure, that they did not affect the accuracy and overall validityof the concentration that was obtained. Thisinformation can be useful for a variety of applications such as in basichousehold applications like cooking and in industrial uses in the agriculturesector. As seen in the experiment, the higher solute concentration the solutionwas, the more dehydrated the potato became as the water inside of the potatowould travel to the other side of the semi-permeable membrane and into the sucroseconcentration solution. This process leaves the sugar, starch, left in thepotato as we know starch is unable to pass through the membrane due to its largesize as a polysaccharide (source). This can create a sweeter potato for cookingpractices if needed, as leaving a potato in water before cooking increases thesucrose concentration. Aspreviously mentioned above, aside from the isotonic solution that were present,there were also hypertonic and hypotonic solutions in the experiment.
In ahypertonic solution, the potato would shrink in size, as the soluteconcentration in the cell is lower than that outside of the cell, causing waterto diffuse out of the cell. The opposite occurs in a hypotonic solution, as thepotato would grow in size, as the solute concentration in the cell is higherthan the solution outside of the cell, causing water to diffuse into the cell. Thisinformation may be deemed useful to those in the agricultural industry, as itallows them to determine the proper conditions and environments in which theiragriculture grows in. Based on the experiment, growing a potato in a hypertonicor hypotonic solution could cause the potato to either shrivel and lose out onits nutrients, or swell up with water, neither of which would be idealconditions for growing food.