Experiment to Investigate Osmosis in Potatoes Essay

The channelize of this experiment is to check out the exertion of urine in and out of nominate carrels. The cells chosen for study go away be taken from spud pipingrs. first of altogether I lead explain what osmosis is. Osmosis is the passage of irrigate from a realm of high urine concentration finished a semi permeable membrane to a region of pocket-size irrigate concentration. This definition contains ternion of the essence(predicate) statementsa) It is the passage of piss system with a semi permeable membraneb) It is the passage of peeing from a region of high water concentrationc) It is the passage of water to a region of low water concentration.All the above statements ar included in the definition, and squ ar up certain aspects of it.Semi-permeable membranes be real thin layers of material which everyow much or slight things to pass through, but prevent almost others. A cell membrane is semi permeable. They altogetherow small molecules like oxygen, water, amino acids etcetera to pass through but volition not allow larger molecules like sucrose, starch, protein etc. through. A region of high concentration of water is either a very dilute declaration of something like sucrose or unpolluted water. In from each(prenominal) one case in that respect is a lot of water a high concentration of water. A region of low water concentration is the opposite of the above, i.e. a very high concentration of sucrose theme a low water concentration.The water content of builds varies depending on environmental conditions. In Land marks this water plays a vital mathematical function in the keep back of tissues and the transport of materials roughly the organism. Lack of water leads to wilt disease and eventually death. Water is mainly absorbed through the roots, which ar c all over in specially adapted root hair cells, with large uprise areas and thin cell breakwaters to aid absorption. It is drawn up the plant through xyl em vessels by a pull resulting from the evaporation of water through thestomata on the leaves.This evaporation is called transpiration and the xylem flow resulting is called the transpiration stream. Soluble food substances formed during photosynthesis are transported around the plant in the phloem tubes. This movement of water through the plant in the xylem vessels or phloem tubes is similar to the flow of blood in humans as it transports soluble mineral salts, nutrients and auxins, (plant hormones), from place to place. The evaporation of water from the leaves also removes heat energy from the plant and helps to prevent overheating.Transpiration pulls water up the plant stem but osmosis is the process whereby water is drawn into or out of cells and tissues. Osmosis is the flow of water by diffusion through a differentially permeable membrane from areas of high water concentration to regions of low water concentration. The diagram below illustrates thisWater end freely reach all membrane. The cellulose cell wall does not act as a semi permeable membrane and lead allow most substances that are dissolved in water to freely pass through it.Whether water enters the cell by osmosis or not testament depend on the rest period between external and cozy solute concentrations and the state of the cell. If the solutions on each side of the differentially permeable membrane are equally heavy so there ordain be no net movement of water across the membrane. This is called an equilibrium state and the solutions are referred to as creation isotonic. A solution that contains more solute particles than another, and is hence more concentrated, is referred to as beingness hypertonic. The less concentrated solution is hypotonic. This concentration of solute particles is usually described as a hoagieity.Even if the solute concentration external to the cell is hypotonic to the vacuole limit the cell leave not continue to take in water by osmosis for eer. The cellulos e cell wall provides a rigid barrier to torrential expansion. A cell that is full of water is called turgid and apprizenot expand exclusively as the outward haul on the cell wall is fit by the inward force of the stretched wall. This wall pressure is called turgor pressureand the inborn outward force on the wall is called osmotic pressure.At the other extreme, a cell placed in a solution that is hypertonic to its contents give lose water by osmosis. The cytoplasm result cease to exert a pressure on the cellulose cell wall and the cell, described as flaccid, will lack support.Water passing play target continue to such an extent that the cytoplasm, and attached cell membrane, contracts and detaches from the cell wall. A cell in this condition is give tongue to to create undergone plasmolysis. This very rarely, if ever happens in nature.As osmosis is the diffusion of water molecules and as diffusion is the hit-or-miss movement of particles from areas of high concentration to low concentration it might be expected that every factors that speed up or slow blue the movement of these particles would affect the rate of osmosis.Using knowledge of the process of osmosis and with a good understanding of one thousand I should be able to localise the solute concentration of the vacuoles in white murphy tuber cells. As it would be unfeasible to measure with any degree of accuracy the expansion or capsule of cells on an individual basis I have decided to nail at gain or exhalation of water in foothold of join on or step-down in mint. Mass, I impression, will be a more consummate way of recording the change of the white stump spudes as when measuring length, it does not take into account the change in diameter of the fighting. I will also look at the increase or decrease in length to verify the accuracy of my results and compare the dickens readings. A cell placed in an isotonic solution should instal no change whereas one placed in a hypert onic solution will lose mass.For this experiment, I will have to rent a factor to vary. These factors are meter of the sucrose solution approach area of the spud Type of white potato vine manipulationd Age of the potato pH of the sucrose solution TemperatureThe factor I have chosen to vary is the molarity of breadstuff solution as I view this will be easy to regulate as the concentration can be easily altered using distilled water. I will use 1 molar solution and alter the concentrations as certifyn belowMolarity of moolah solutionAmount of waterAmount of sucrose solution0.0500.2410.4320.6230.8141.005For this experiment I will imply 1 large potato to produce 18 potato tubers bobfloat woodborer distilled water 1 molar sugar solution pipettes 18 test tubes ruler to measure length of potato tubers electric relief to measure the massI have selected the above equipment because I feel it will help me to ensure close results. To ensure a beautiful test I will take all my po tato samples from the equivalent potato using the analogous cork borer and keep all of my apparatus the same. I will try and treat each potato tube the same. I will measure each potato tube separately to ensure accurate measurements and carry out the procedure 3 times for each molarity tested. This will mean that I will need to measure 18 potato tubers. Three results will modify me to take an bonnie result, making the results, hopefully, more precise and reliable. If one of the results come outs very different to the others, I shall let out it as an anomalous result and retake the reading.When I carry out this experiment, I will get a potato and take some tubes from it using a cork borer I will then cut these tubes into shorter lengths and measure the length and mass of each of the 18 lengths. All the lengths will be cut to 25mm. The solutions will be altered according to the molarity required and cm3 of each solution placed in each test tube. Each molarity will occupy three t est tubes. The chips will then be throw away into each test tube and left over night. They will then be taken out of their test tubes, dried lightly with a paper towel and the new mass and lengths recorded. Once the results have been collected, they will be tabulated and analysed. A interpretical record will be drawn and any trends noticed explained.Prior to the experiment we carried out a short pilot program test, using potato chips and solutions of strength 0.0, 1.0 and 2.0 molar solutions. The chips were25mm in length each, and each chip was placed in 5 cm3 of either distilled water/1.0 molar / 2.0 molar sugar solutions and left for 30 minutes. The potato chips were then calculated and the results recorded. They are shown belowChipSolution1Water21.0 molar32.0 molarChip numberOriginal lengthResultant length125mm29mm225mm24mm325mm20mmThese results show that a potato chip placed in water will gain in length, a weak sugar solution will lose length and a strong sugar solution will lose length also. The results from this test will allow me to choose an tolerate range of moralities in order to find out what the concentration is deep down the cell vacuole. I am going to investigate 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 molar sugar solutions. I have chosen these concentrations to try and accurately find when there is no net movement of water, hence the concentration of the cell vacuole.From previous work done on osmosis, I predict that molarity and average change in mass/ length will be indirectly proportional. I envisage there will be a interdict correlation between the two. I think that there will be both loss and gain in mass discovered. I think the represent will look like this but there will be no plasmolysed on my graph, as I do no expect my measurementsto go that far. I hope to be able to identify the steer when there is no net movement of water.Analysis of ResultsThe Consequences of Osmosis in plant cellsPlant cells always have a strong cell wall surroun ding them. When the take up water by osmosis they scram to swell, but the cell wall prevents them from bursting. Plant cells pop off turgid when they are put in dilute solutions. Turgid means swollen and hard. The pressure at bottom the cell rises, eventually the internal pressure of the cell is so high that no more water can enter the cell. This still or hydrostatic pressure works against osmosis. Turgidity is very important to plants because this is what makes the green parts of the plant stand up into the sunlight.When plant cells are placed in concentrated sugar solutions they lose water by osmosis and they become flaccid this is the charter opposite of turgid. If you put plant cells into concentrated sugar solutions and look at them under a microscope you would see that the contents of the cells have shrunk and pulled away from the cell wall they are said to be plasmolysed.When plant cells are placed in a solution which has exactly the same osmotic strength as the cells th ey are in a state between turgidity and flaccidity. We call this incipient plasmolysis. incipient means about to be. When I forget to water the embed plants in my study you will see their leaves droop. Although their cells are not plasmolysed, they are not turgid and so they do not hold the leaves up into the sunlight.Graph 1 shows the average percentage change in length of the potato tubers. It shows that as molarity increases the average change in length decreases. The graph drawn looks accurate as the curve did not have to be one of outflank fit, but went through all of the points plotted masking that all the readings were accurate. The potato tubers gained/ loss length, the molarity increases the sugar solution becomes more concentrated, and moreconcentrated than inside the cell. At 0.2M solution there is no net movement of water. As the strength of the concentration increases the cells shrink and become flaccid.Graph 2 shows the average percentage change in mass of the pota to tubers. It shows that as molarity increases the average change in length decreases. This graph is very similar to the graph viewing the length loss or gain, but appears less accurate as there is an anomalous result. This is at 0.4 molar, it lies off the outdo-fit curve drawn by 9.2%. The curve is one of best fit and follows the same trends as graph 1.My results be fairly accurate and although the graph showing length seems to be more accurate as it is a curve that goes through all of the points, it only shows the change in length, and not in mass. The graph showing mass change 2 gives a more accurate view of what happened as it takes into account the expansion of the potato both ways and has a broader percentage change range. This means that rather of just spanning 30% in total (as does graph 1) it spans 80% (as does graph 2). This gives a broader field of results and is therefore more accurate, as the mass is a more accurate result than length as the potato chip will get wid er as well as longer. My results do seem to be reliable, as the graphs drawn support my prediction and seem accurate as they all lie on a smooth curve. oddmentFrom the results obtained, I can conclude that the average gain or loss in mass of the potato chip is indirectly proportional to molarity. I can also tell that average gain or loss in length of the potato chip is indirectly proportional to molarity. two of the results show a negative correlation. I can now say that the more concentrated the solution, the more mass/length is disconnected. This is because the water inside the cell moves out, causing the cell to shrink. When the cells are in a less concentrated solution they gain in length and mass as water is taken into the cell and the cell swells. The results gave enough information to support my original prediction. Both of the graphs cut the x-axis at 0.2, showing that the molarity of the internalsolute of a cell is 0.2m. This also shows that my results were very alike an d reliable.EvaluationMy results seem to be very accurate. I can tell this because when the points were plotted they all lay on the curve, apart from one anomalous result, 0.4Mon the graph showing mass. There was however only one anomalous result and the others were all very reliable. This may have been because the results had an average taken so it may not have been accurate. I could increase the accuracy by victorious more repetitions which should make the average more accurate. As the potatoes were left over night, the temperature changed which may have affected the results, but it should not have make a drastic difference to the graphs as all of the potatoes were subjected to exactly the same temperature changes.This could be improved by placing the test tubes into a water tubful so they were kept at a constant temperature. The same potato was used in each of the experiments, which may also have contributed to the dependability of my results. The mass was more accurate to mea sure for many different reasons. length does not take into account the change in diameter of the chips, and you can not measure fractions of millimetres on a ruler, but the electric balance will record change from 2 decimal places,e.g. mass 1?43 1?34length 25 23whilst length can only be measured to the nearest millimetre. For the mass, we had to be careful that all the potato chips were dried in the same way as this may have altered the reading. This may have been what caused the anomalous results, as it was lighter that the best fit line i.e. some water may have been lost through harder drying, or squeezing during the drying process. If some of the water evaporated overnight, it would have incresed the molarity of the solutions, thus making the results innaccurate. This could be combatted by putting a spile in the top of the test tubes to stop the evaporation and keeping the sugar slution concentrations the same.To improve the accuracy of the results I would include more concent rations tofind the point of plasmolysis as in my experiment, I did not get to the point of plasmolysis in my experiment, so if I was to extend this experiment, I would investigte a wider rage of concentrations to investigate furthur and increase accuracy. I would also increase the repetitions to 5 per molarity and increase the molarity to try and find the point of plasmolysis. I could also decrease the range between each molarity (every 0.05 for example) to try and find the exact concentration of the potato cells where there is not net gain. This investigation was succesful but could still be made more accurate by some of the above ways.