*Picture Of onion cells in saline not available.
E rror Analysis :
Lab 1A – The data collected in this lab experiment did not seem to contain any inconsistencies, so therefore no human error is detected.
Lab 1B – In this lab experiment, the data seems to be compliant with the data collected by the other lab groups, so no human error was thought to have happened.
Lab 1C – There was some discrepancy in this experiment in the solution’s percent change in mass of potato cores. The data decreases consistently until the solution, so human error is thought to be a factor in this. Some mistakes that could have taken place are miscalculations in initial and final masses or problems with the molarity of the solution itself.
Lab 1D – In this part of the lab, only calculations were made, so no human error probably occurred during this time.
Lab 1E – In part 1E, after adding the NaCl solution to the onion cells, the cells should have reduced in size, but no reaction took place. This may have occurred in part because the onion itself was already dried out and dehydrated, or while the onion was being looked at through the microscope, the heat from it may have caused the cells to loose water.
During the experiment conducted in Lab 1A, the results and data collected make it possible to conclude that glucose and Iodine Potassium Iodide can pass through a selectively permeable membrane and will if the concentrations on either side are not equal. In Lab 1B, it can be concluded that sucrose cannot pass over a selectively permeable membrane, but instead water molecules will move across the membrane to the area of lower water potential to reach dynamic equilibrium. Lab 1C provided information that helps to conclude that potatoes do contain sucrose molecules. This can be stated because the cores took in water while they were emerged in the distilled water. This means they had a lower water potential and higher solute potential than the distilled water. The solute potential is equal to about a solution of sucrose according to the data collected. During Lab 1D calculations were made and questions were answered to help give a better understanding of water and solute potential. If the onion cell experiment in part 1E of the lab would have produced correct results, conclusions could have been made. It is thought that the onion cells would have plasmolyzed due to the addition of NaCl to the cells. This shows how the onion cells had high water potential and moved to the area outside the cell with lower water potential. Then, after adding water back to the cells, water would have moved back into the cells increasing turgor pressure.
The water potential played an enormous role in each part of this lab. Since water moves areas of high water potential to areas of low water potential, reactions took place in each part resulting in different conclusions being derived from them. Water potential was a key element in each part of the experiment. In plant and animal cells, loss or gain of water can have different effects. In a plant cell, it is ideal to have an isotonic solution. If the solution is hypertonic, the cell will shrivel from lack of water intake. Inversely, if the solution is hypotonic the cell could take in too much water and the cell will lyse and break open. For a plant cell, the ideal solution is a hypotonic solution because the cell takes in water increasing turgor pressure which keeps the cells tightly packed and keep their shape. If the solution is hypertonic, the cell will plasmolyze and died from lack of water. In an isotonic solution, the plant cell does not have enough turgor pressure to keep is shape.