Figure 1. Comparison of the percent weight changes of three solutions and the osmolality (number of particles of solute/L) for each solution.
Table 1. Coursewide data comparing means of water potentials and osmolalities required to produce zero weight change of potato cores in three treatment solutions. Also includes chi-square and P-values for each set of data.
Solution Potato Water Potentials (bars) Osmolalities (Zero Weight Change) Means Chi-square P-value Means Chi-square P-value
Sucrose -8.70 2.17 0.337 0.351 2.71 0.256
Glucose -9.53 0.388
NaCl -8.59 0.344
According to Figure 1, the course-wide data - excluding the NaCl regression line data collected from our lab group - comparing percent weight change and osmolality followed a fairly consistent pattern. Both NaCl and sucrose have an x-intercept of approximately 0.34, while glucose has an x-intercept of 0.4 and NaCl (our group) has an x-intercept of 0.23. The point at which the regression lines cross the x-axis represents a zero-weight change in the potato cores. Table 1 demonstrates the means for both the water potential of the potato cores in NaCl, glucose, and sucrose, as well as the osmolalities for each solution at which the cores no longer gain or lose weight. NaCl had the highest water potential at -8.59 bars, followed by sucrose at -8.70 bars and glucose at -9.53 bars as the lowest value. The p-value, or probability that these results were due to
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My prediction is that as the concentration increases, the potato cell will lose more weight. This is because of the osmosis of water particles from the potato cell cytoplasm to the solution, resulting in a loss of weight. As the concentration decreases, the potato will lose less weight until a certain point where the osmosis of particles in and out of the potato cells will be equal. I also predict that as the salt
The results supported the hypothesis that the osmotic potential of potato would be somewhere that intermediates between a dilute solution and concentrated solution. When the change in mass of the potato
The graph above indicates that as the concentration of sucrose solution (%) is increased, the percentage change in mass decreases, thus it can be supposed that there is a negative correlation between the sucrose concentrations and the mass of potato cubes. It is also apparent from the graph above that an error has occurred during the 15% sucrose trial as it appears as an outlier also it can be estimated from the graph that approximately10% sucrose solution is the isotonic condition as there is no big change in mass.
An investigation of the glucose concentration of the cell sap in potato cells In this experiment I intend to investigate the effects of osmosis on potato cells. Specifically, I intend to use my knowledge of osmosis to investigate the glucose concentration of the cell sap in potato cells. Osmosis is a method by which water levels on either side of a semi permeable membrane may balance themselves. It occurs between regions of high water concentration and low water concentration.
Osmosis is defined as the tendency of water to flow through a semipermeable membrane to the side with a lower solute concentration. Water potential can be explained by solutes in a solution. The more positive a number is more likely it will lose water. Therefore should water potential be negative the cell the less likely it will lose water. In using potatoes the effects of the molarity of sucrose on the turgidity of plant cells. According to Clemson University, the average molarity of a White potato is between .24 M and .31 M when submerged in a sorbitol solution. This experiment was conducted with the purpose of explaining the relationship found between the mass in plants when put into varying concentrations of sucrose solutions. Should the potatoes be placed in a solution that contains 0.2M or .4M of sucrose solution it will be hypotonic and gain mass or if placed in .6M< it will be hypertonic and lose mass instead. Controlled Variables in this lab were: Composition of plastic cups, Brand of Russet Potatoes, Brand of Sweet Potatoes and the Temperature of the room. For independent variable that caused the results recorded it was the different Sucrose concentrations (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M). The dependent variable was the percentage change from the initial weighs to the final. The cup with .4 molarity was the closest to an isotonic solution and was used as the control group for the lab. Water potential is the free energy per mole of water. It is
Van’t Hoff’s Law suggests that the osmotic potential of a cell is proportional to the concentration of solute particles in a solution. The purpose of this experiment was to determine if there are any differences between the osmolalities, the no-weight-changes of osmolalities, and the water potentials of potato cores in different solutions of different solutes. The percent weight change of the potato cores was calculated through a “change in weight” method. The potato core’s weight was measured before and after they were put into different concentrations of a solute for 1.5 hours. In our experiment, there were no significant differences from the osmotic potentials of our results and the osmotic potentials of other scientists work. Ending with chi square values of 2.17 and 2.71, and p values of 0.256 and 0.337, concluding that there is no difference in water potentials of potato cores in different solutions of different solutes at varying concentrations.
However, there is not going to be net movement of water entering or exiting the cell. Hypothesis: Based on this experiement: estatimating the osmolarity of potato tissues by immersring potato rectangles: I may weight my thoughts and knowledge over on that concentrated sucrose solution will in some way cause the mass of the potato itself, then decrease as water is more likely to move out of the cells. However, low concentrations of sucrose solutions will effect, however, the mass of the potato rectangle will in some way increase because the water is going to move into the plant cells. Independent variable:
Abstract: This experiment discusses the effects that saline and non-saline environments have on potato strips. Two potato strips were cut to lengths of 2 inches and each strip was placed in one of two solutions. The solutions used were a.) a mixture of 24ml tap water and 1tsp salt and b.) 24ml tap water. This experiment was conducted over a period of five days and observations to each container were made daily at the same time.
However one beaker received 100 mL of Deionized water with a molarity of 0.0. Afterwards a cork borer was pushed through the potato and was twisted back and forth. Once the borer was filled it was removed from the potato. Pushing the potato cylinder out of the borer, this this step was repeated six more times in order to get seven undamaged potato cylinders. Using a sharp razor blade, the potato cylinders were both cut to a uniform length of about 5cm, and were removed of their potato skins. The potato pieces were also cut in half to give the cells a greater surface area in which it was easier to absorb the solution. After the cylinders were weighed on a balance and the data was recorded in Table 4. Using the razor blade each potato was cut lengthwise into two long halves. Then the potato pieces were transferred to the water beaker and the time they were submerged was recorded. This step was repeated for all potato cylinders in which the pieces were placed in solutions 0.1 to 0.6 M. The potatoes were incubated for ninety minutes. At the end of the incubation period the time was recorded. Then the potato piece was removed form the first sample. Next potato pieces were weighed the and the final weight was recorded in Table 4. This procedure was repeated until all samples had been weighed and recorded in the chronological order they were initially placed in the test solution. Afterwards the table was completed by recording the
The solutions of 2% and 10% both reached dynamic equilibrium as neither had lost nor gained water during the experiment, This indicates that the results may have been inconclusive because two, widely various solutions could not have both reached dynamic equilibrium with the potato cell. This leads to the idea that there were a few errors made while performing this experiment, which most likely had an effect on the results, causing them to be non-reliable. Firstly, the test tubes had not been properly cleaned before the experiment took place. This caused a strange smell and a colouration of the potato tuber, it may also have increased or decreased the osmotic potential, though this cannot be known as it is not known what chemical residue may have been left in the test tubes. Secondly, the potato cells had been left in for three days instead of the recommended 24hrs. This mistake may have caused the soft, sogginess of the potato which rendered it difficult to pat dry and handle. During this part of the experiment, pieces of the cells were broken and lost down drains or stuck to the paper towel, as well as many still containing much excess water. Because of this, the weights measured could be inaccurate and therefor unreliable. Based on the data found by Clemson University Student Robert.
This experiment went through a series of steps, starting with placing 100mL of different concentrations of sodium chloride (NaCl) in separate beakers. Sections of potato were punched out, then dried and recorded for initial weight. Five were placed in each concentration of the sodium chloride, and left to sit for an hour and a half. The mixtures were swirled about every fifteen minutes to prevent shells of water from building up around the core and causing error in the results. After the hour and a half, we removed the potato sections, dried them and then weighed them for the final weight.
In conclusion when the molarity level was at 0 and at .2 the potatoes had gained mass so therefore they were placed in a hypotonic environments. When the molarity level was .4 and above the potatoes loss mass so therefore they were placed in hypertonic environments. So the different in concentrations does change the mass of the potatoes because they determine the osmosis environments.
Data: Effect of Solute Concentration on Osmosis in Potato Cells (for the 6 groups of our class)