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Osmosis Investigation

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Osmosis Investigation To understand my task, I will first understand the concept of osmosis. Osmosis is the process of water movement from a region of low concentration to a region of high concentration across a semi permeable membrane, which is simply a thin membrane allowing the passage of small molecules. Ex: water molecules. The solutions of high concentration and low concentration are generally referred to as hypertonic and hypotonic solutions respectively. Hypertonic solutions have less water molecules and thus are said to have lower water potential than hypotonic solutions; in hypertonic solutions, solute molecules (ex: sugar, salts) are dissolved and when this occurs, some water molecules form a cluster around them. Thus, there are less free moving water molecules. Therefore, water potential is simply the measure of whether the solution is likely to gain or lose water; it is also the pressure exerted by the freely moving water molecules. It is measured in kilopascals. (kPa) Therefore, osmosis may also be defined as the water movement from a region of high water potential to a region of low water potential across a semi permeable membrane. Osmosis is a very important biological process as it involves the transfer of water in and out of cells. Animal and plant cells both have the presence of the jelly-like substance known as the cytoplasm, made up of about 90 percent water with dissolved sugars and salts. This forms a weak solution. Plant cells also have a large space known as the vacuole containing a weak solution of sugars, salts and water known as the cell sap. If the concentration of the solution is more concentrated in the cell than its external solution, then water moves into the cell. This is particularly important in plant cells, as they will become turgid and strong. If too much water enters animal cells, they will burst and this is damaging. However, plant cells can limit the amount of water that enters the cell due to the cell wall; when much water enters ...read more.


Furthermore, when inserting the cork borer into the potato, I have made sure to place the potato on a raised platform and made sure the potato was not cupped in my hand to prevent any injury to my hand. Analyzing Evidence With the data obtained from my experiment, it is now necessary to fully understand them and analyze the results. More than that, it is important to prove why the results are given as so. To do so, it may help to construct a bar graph to clearly present the data obtained from the experiment. The bar graph on the next page clearly reveals the change in length for the potato tubors in the different concentrations of solution; it presents the initial length of the tubors and its final length. From this graph, it is obvious that with a less concentrated solution, the potato tubor actually gains length. For example, when the potato tubors are placed in distilled water, from four centimeters, they increase in length to 4.43 centimeters, an increase of 43 millimeters. This relies on the fact of osmosis; if a cell is placed in a less concentrated solution, then in order for equalization to occur, that is for the concentration to be equal on both sides, then water must move into the cell so that its cell sap becomes diluted and so that the concentration gradient is eliminated. In this case, since the potato cells inside the tubor obviously have cell sap, a mixture of salts and sugars with water, it forms a weak solution. Even though it is weak, it is still more concentrated than the distilled water. Thus, in order for equalization to occur, some of the distilled water must move across the cell membrane of the potato cell and enter it. In this case, the cells will become bloated or turgid; they become firm and full. Due to this, the potato tubor will increase in length as the potato cells have become firm and turgid; they occupy more space and so the tubor increases in length. ...read more.


Furthermore, in order to prevent the tubors from being irregular, I will use only those potato tubors that are almost a perfect cylinder. In this case, the readings in mass and length are more accurate. Another common error to overcome is that of parallax; when using the measuring jar to confirm 30mL of solution to be used, I will make sure to take this reading at eye level so that I am actually using an exact volume of 30mL exactly. Also the parallax error can be avoided when cutting the potato tubors to an exact four centimeters; its length should be noted at eye level to confirm the length of the tubor is four centimeters. And finally, in order to prevent the concentration of potato cell sap from altering, I will use the same potato. Though my experiment is suitable and appropriate, it can be improved further more my using a different range of concentrations of sucrose solution to better reveal the change in mass and length of the potato tubors when placed in these solutions but more importantly to reveal the exact concentration of the potato cell sap. Thus, in this case, it may perhaps be better to use a range of concentrations between 0.25M and 0.5M. Thus, this will help to narrow down the exact concentration of the cell sap. The experiment may also been carried out using an egg rather than potato tubors or perhaps another substance could have been used to more appropriately show what is happening when the substance is placed in different sucrose solutions. Even though, in conclusion, I have found out that when a substance is placed in a more concentrated solution, it loses water in order for equalization to occur and thus in the case of the potato tubors, they will decrease in mass and length. Furthermore, when placed in a less concentration solution, the tubors will gain water in order for equalization to occur and so they will increase in mass and length. And also from my experiment, I have determined the potato cell sap concentration to be 0.46M. ...read more.

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