Abstract
In the Biology Laboratory session, I worked with two partners on Osmosis. It means the diffusion of water across a selectively permeable membrane, which is the plasma membrane in a biological system. The purpose of this activity is to find the weight of potato cores in two separate beakers. One beaker contains distilled water and other one is 10% NaCl. Before performing the laboratory test, we made two hypotheses. The first one is the weight of potato cores in 10% NaCl will decrease in gram. Second is the weight of potato cores in distilled water will be the same in gram. We performed it and recorded the weight every five minutes for thirty minutes. After we completed the activity, we looked at the table. Our hypothesis was testable. However, the first one was proved to be corrected while the second proved to be not corrected. According to website www.spartechsoftware.com, through osmosis, water naturally moves from areas of low salt concentrations to areas of high salt concentrations. Adding salt to the water creates a higher salt concentration in the water in the dish than in the water contained in the potato. Consequently, the water in a potato that is soaking in salt water will migrate out of the potato leaving a rather disgusting, mushy spud.
Introduction
When my group and I started doing the laboratory activity, we asked ourselves, “What’s the purpose of doing this activity?” The purpose of doing this activity is to do testing on weight of potato cores in both distilled water and 10% NaCl. NaCl is a salt. Not only just that, the other objective is to calculate the percent difference in weight. Before I began this activity, I read the laboratory manual seven to make sure that I know what I am supposed to do. I a...
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...stilled water did not support my result because it did not stay the same in gram. I wondered why did that happened. Both inside and outside of potato is water. I could say that it is stimulate because it went up and down. Calculating the percent difference was the big factor in comparison of both cores in distilled water and 10% NaCl.
Citations:
1) spartechsoftware.com. Copyright 1997-2005, SparTech Software [updated: n/a] Available from http://www.spartechsoftware.com
http://www.spartechsoftware.com/reeko/Experiments/ExpSpinelesPotatoes.htm
2) herbarium.desu.edu. © 2006 Arthur Tucker [updated: n/a] Available from http://herbarium.desu.edu
http://herbarium.desu.edu/pfk/page17/page18/page19/page19.html
3) Biology Laboratory Manual, 7th edition. Copyright 2009. Laboratory 7; The Passive Transport System. Gallaudet University: Biology Department; 2009. P. 67
The Effect of Solute Concentration on the Rate of Osmosis Aim: To test and observe how the concentration gradient between a potato and water & sugar solution will affect the rate of osmosis. Introduction: Osmosis is defined as, diffusion, or net movement, of free water molecules from high to low concentration through a semi-permeable membrane. When a substance, such as sugar (which we will be using in the experiment we are about to analyse), dissolves in water, it attracts free water molecules to itself, and in doing so, stops them from moving freely. The effect of this, is that the concentration of (free) water molecules in that environment goes down. There are less free water molecules, and therefore less water molecules to pass across a semi-permeable membrane, through which sugar molecules and other molecules attached to them are too big to diffuse across with ease.
Conclusion In my conclusion, the potatoes with the lowest concentration gained the most mass, and would become hard relating back to the Turgor theory I stated earlier. In contrast to this, the potatoes in the most concentrated solution lost the most weight thus becoming plasmolysed and limp also relating back to the background I have mentioned earlier. Evaluation In general the experiment was succesful the results were consistent and also were in accordance with the theories made at the start.. The experiment could have been improved by: · More subjects used instead of potatoes · More potatoes · Wider time ranger · Different molarities Using this variety of methods could have improved the experiemnt, however I was generally satisfied with the results of this osmosis experiement.
The experiment is aimed at giving a better understatement of osmosis process and the different conditions in which osmosis occurs.
Investigate the Osmosis of Potato Cells in Various Salt Solutions. Introduction I have been asked to investigate the effect of changing the concentration of a solution on the movement of water into and out of potato cells. I will be able to change the input of my experiment. The input variable is the concentration of the solution.
To investigate the osmotic effect of changing the concentration of sucrose solution; distilled water, 20% sucrose solution, 40% sucrose solution, 60% sucrose solution on the change in mass of potato cylinder after 30 minutes of being in solution.
Water Potential of Potato Cells Aim: To demonstrate the Water Potential of Potato Cells. Objectives: · To show the water potential of potato cells using various measured concentrations of a sucrose solution and pieces of potato. · To record and analyse data to verify observed results. · The method and procedure was carried out as per instruction sheet. Observations: The experiment shows that the lower the concentration of the sugar solution, in the Petri dish, the mass of the potato increased.
So what is happening is water is moving from a high concentration, i.e. a dilute solution to a more concentrated solution. Preliminary Work on Osmosis I am going to test carrots in a small osmosis experiment to see how the experiment works with carrots and salt solution and water. Variables 1) Temperature - Keep the same 2) Number of days left soaking - Keep the same 3) Size of beaker - Keep the same 4) Size of carrots - Keep the same 5) Concentration of salt solution -
However, the solution could be more water than salt so the water from the solution could be more concentrated than the water inside the potato cells. If so then In theory the water in the solution should diffuse into the potato. cells and increase in mass. Apparatus: Potato to perform the experiment on. Thin metal tube to cut potato chops with.
Semi permeable membrane [IMAGE]Water molecules Salt molecules [IMAGE] Osmosis is the movement of water molecules across a semi permeable membrane from a region of high water concentration to a region of low water concentration. My prediction in this investigation is that the solution with the least salt will make the potato weigh more, thus the potato in the distilled water solution will weigh the heaviest, because there will be a higher concentration of water molecules in the distilled water than inside the potato cylinder. Therefore, water will move in from high concentration to low concentration this will increase the mass. I based my prediction on the process of osmosis, which is a special type of diffusion. It occurs across a permeable membrane, which allows some particles to diffuse through it and not others.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Determining the Concentration of the Cell Sap in Potato Storage Tissue Aim: To determine the concentration of the cell sap in potato storage tissue. By using Osmosis, determine what the sugar concentration of cell sap is. Prediction I predict that the potato segment in the distilled water will definitely gain in weight because the solution outside it has a much higher concentration of water then in the cell sap meaning Osmosis will occur and the potato segment take in water. I predict that 0.2M sugar solution will also gain weight because it still has quite a high concentration of water outside the potato. The potato in the 0.4M solution will gain weight but the potato in the 0.6M and 0.8M solutions will lose weight.
Osmosis in Potato Tubes Osmosis: Osmosis is the movement of water molecules through a semi-permeable membrane from a high concentration to a low concentration. Diagram: [IMAGE] [IMAGE] Aim: To see the effects of different concentration of sugar solution on Osmosis in potato tubes. Key factor: In the investigation we change the sugar solution from: 0%-10%-20%-30%-40%-50% this is the independent variable; the dependant variable is the change in mass. Prediction: I predict that all the potato tubes in pure water or low concentration sugar solution will swell because water enters their cells by osmosis.
water in the potato, then the water will go out of the potato and into
3. Why are the crucible and lid heated at the beginning of the experiment before being weighed?
Prediction I think that when the potato is placed in distilled water the potato mass will increase. This is because water, has, if pure, a weaker concentration than the potato, and the water molecules move in through a partially permeable membrane by osmosis. If the potato is in a high concentration salt solution, the potato mass will decrease because the potato is less concentrated than the salt solution, and the water will move through the partially permeable membrane into the stronger solution. However, if the potato mass stays the same after the experiment, this means that the water/salt solution and the potato must be of equal concentration.