Potato Osmosis Lab Report

You may have observed the reaction of naturally-occurring catalase in tissue from either liver of potato. Design an experiment to determine if the amount of catalase varies from tissue to tissue (e.g. 200 g of liver compared to 200 g of potato).

Students will label 3 test tubes hot, cold, and room temperature and place potato cub (3X3X3 cm)

Purpose: To determine the concentration of solute in the potato’s cytoplasm by measuring the change

Using different sizes of potato could show us whether the concentration of enzyme affect the rate of reaction. However, this would not be a practical independent variable as the S.A to volume ratio would not be proportional and the size of the potato to get significant results would be very hard to change. It would be very hard to cut the potato tubers to exact measurements and that could lead to the results becoming inaccurate. An option could be to cut the potato tube into small 1 cm bits and pile then up on top of each other in the test tube, but this again would prove to be impractical as then not all of the surface area of the potato would be exposed to the substrate and this would make my results unreliable. It may also prove to be impractical as having the tuber bits piled on top of each

There are 3 potential states that the cell could be in depending on the type of solution:

There were three test tubes in which the experiment was held. A relatively equal sized portion of raw potato (this contained the enzyme [a biological catalyst] hydrogen peroxidase) was placed in each tube. Then, enough water to cover the potato was added. Proceeding this, each of the test tubes were assigned a temperature; cold, room temperature or warm (this was written on the tag so that they were not confused). The test tube destinated ‘cold’ was placed in a ice bath for five minutes. At the same time, the ‘hot’ test tube was placed in a hot water bath for five minutes. Meanwhile, the room temperature test tube sat at room temperature for five minutes. When the five minutes were over, the test tubes were returned to the rack (so that they were able to be observed). Then, the test tubes were allowed to sit at room temperature for five more minutes. Once that period of time was over, 2 ml of hydrogen peroxide (the substrate) was added to each tube.

Procedure: Variables: Controlled- water and size of potatoes. Manipulated variables- potatoes growth based on contents of solution.

After they soaked, they were dried, placed back in the Petri dishes, and individually weighed again to determine whether each slice was hypotonic or hypertonic to the NaCl solution it was placed in, based on percent weight change. When the experiment was complete, Microsoft Excel was used to further analyze the data by viewing the percent weight changes for each potato slice in the form of a Scatter Plot

Measure and add 5cm3 of buffer solution using a measuring cylinder with the pH 3 into a test tube using a pipette and place the potato cylinders into the test tube.

out the potato and dry it to ensure excess water is not added to the

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 hypothesis for this experiment was that at 0m and at .2m the potato core was going to swell making the surroundings it was in hypotonic. For .4m it was stated that the potato core would stay the same, making the surroundings it was in isotonic. For that last three solutions, .6m, .8m, and 1m, it was thought that they would shrink, so that would mean that that the environment that they were placed in was hypertonic. Although these

8. Use the plastic forceps to remove the potato cylinders from the beakers (keep them together in the same group), and blot off the excess solution weight on them with the paper towels.

First I gather all my materials needed for the experiment (see materials list). Second I peel and slice potatoes weigh each potato in grams. Get these slices to weigh the same in mass because if they vary to much in mass that could affect the results of the experiment. Third I place each potato in its own beaker. Fourth once the potatoes are placed in beakers I make sure to place enough solution to fully cover the potato. Each beaker should have a different amount of

Then, each group of students received the necessary materials to complete the experiment. When the students received the cups, they labeled cups to distinguish between the salt solution, distilled water, and control group. After weighing the cups and finding the mass of the cucumbers, the students poured 50 ml of water in one cup, 50 ml of salt solution in the other, and left the control cup empty. Then, the students placed the cucumbers into the cups and waited 30 minutes for the results. After the 30 minutes, the students removed the cucumbers from each solution and dried the cucumbers with paper towels. The students then weighed the cucumbers again and recorded their results. Lastly, the students found the difference from the original mass of the cucumbers and recorded their results.