The Effect of Salinity on the Cytoplasm and Sap Concentrations between Potatoes, Swedes and Carrots - Lab Report Example

Title: Institution Tutor: Name: Date: Topic: The effect of salinity on the cytoplasm and sap concentrations between potatoes, Swedes and carrots. Abstract Plant tissues have been experimented on to establish various properties related to concentration of solutes in their external environment. It has been postulated that the cell sap and cytoplasm contains proteins that have specific isoelectric points (Pearsall & Ewing, 1926). The properties of these proteins could influence the difference in osmotic potential of different tissues to salute concentration in their external medium. This experiment considers reduction in mass through loss of water from plant tissues placed in varying salt concentrations to investigate salt tolerance and composition of their cell sap and cytoplasm. Data obtained from this experiment will be compared to other studies by Pearsall and Ewing (1926) that investigated protein precipitation and swelling of the tissues when exposed to concentrations of varying hydrogen ions. This experiment established that Swedes and carrots are less susceptible to solute concentration compared to potatoes. Table of Contents Aims and objectives: ……………………………………………………………………...3 Scientific background: ……………………………………………………………............3 Hypothesis: ……………………………………………………………………………….4 Methodology: ……………………………………………………………………………..4 Results: ………………………………………………………………………………........6 Discussion: ………………………………………………………………………………..9 Conclusions/ Recommendations: ………………………………………………………..10 References: ………………………………………………………………………………12 Aims and Objectives of study. The aim of this experiment is to establish the effect of salt solution concentrations on osmosis potential as the main variables used to compare potato tubers, root carrots and Swedes bulbs. This experiment will achieve the objective of determining differences in concentration of sap and cytoplasm between, Swedes, potatoes, and carrots. Introduction (Scientific Background) According to scientific principles, molecules of water are constantly in random motion. Pressure is created when the molecules hit at each other and also on the cell membrane of plant cells, this in turn generates pressure known as osmotic pressure. An osmotic pressure is at equilibrium when movement of water molecules in and out of the cell is equal (Plant water relations, 2008). Osmosis can be defined as the movement of solvent or water molecules from a region with high concentration to that of less concentration through the semi- permeable cell membrane (Plant water relations, 2008). There are two factors which influence osmosis. These are hydrostatic pressure and concentration of solutes in the surrounding media. Osmotic pressure is lowered when solutes are present. The solutes are the dissolved salts in the surrounding media of cell sap. Likewise, hydrostatic pressure generates unfavorable potential for water movement. However, living plant cells have a cell wall which generates turgor pressure against hydrostatic pressure to prevent cell from bursting (Fig.1), instead it becomes turgid (Plant water relations, 2008).This uptake of water by cells through the cell membrane is attributed to the presence of cell sap. The cell sap has highly concentrated solutes that generate the necessary osmotic pressure (Plant water relations, 2008). In contrast, plasmolysis takes place when water moves out of the cell leaving less water inside the cell. In this situation the cytoplasm of the cell collapses and the cell vacuole shrinks. The cell is then said to be flaccid. In this state the cell wall and cell membrane separate (Plant water relations, 2008). Therefore, if pieces of potato, carrot or swede bulbs are placed in a solution with varying concentration of salt, water will move from them to the surrounding solution because of the osmosis pressure created by the salt, as a result there will be reduction in weight of the pieces. Consequently, any increase in molarity of the salt will lead to higher loss in mass until an osmotic equilibrium is established (Pearsall & Ewing, 1926). Hypothesis This experiment tests the hypothesis that concentration of a salt solution has no effect on osmosis rate and loss of mass in potatoes, carrots and swede bulbs. Materials and Apparatus Salt solutions (0.2, 0.4, 0.6, 0.8, 1M), 15 100ml measuring cylinders, Pipette, potatoes, carrots, Swedes bulbs, 8mm cork borer, distilled water, 100ml boiling tube, electronic scales. Methodology. Experiment 1 Measuring cylinders were labeled and arranged in to five sets in three rows on the table. The rows were labeled with a tag for potatoes, carrots and Swedes. The correct salt solutions from 0.0 up 1 molar were added in each of the cylinders with a pipette corresponding to the labeled concentration strengths. A cork borer was used to cut in the center and take thick, uniformly sized discs from each of the samples of potatoes, carrots, and swedes. Electronic scale was used to weigh and note the masses of the discs. The disc pieces were then immersed in the corresponding series of salt solutions with varying concentrations and left for up to 1 hour to allow osmosis to take place (Pearsall & Ewing, 1926). Experiment 2. The same procedure as above was applied in experiment 2, for every sample. However the concentration of salt solution was from 0.0 up to 0.3M. After one hour, a pipette was used to empty the solutions leaving the samples of the pieces in the cylinders. The masses of the disc pieces were again weighed and their masses noted down for every solution correctly. Control experiment was set up by placing a boiled piece of each sample of potato, carrot and swede in a boiling tube and left to stand in a salt solution for one hour and their masses determined. Observation During the experiment it was noted that for each sample of the tissues, there was a slight increase in mass before a gradual decrease. In experiment 1, when the pieces were immersed in salt concentrations of up to 0.1M and left for one hour, it was observed that potatoes did not recover from mass loss but Swedes and carrots were able to survive and start to gain weight between 0.4- 0.6M. It was also observed in experiment 2 that potatoes were easy to loose water at low salt concentrations of 0.15M while Swedes and carrots maintained a steady water balance up to 0.30 M when they started to loss mass. Fig.1 Diagram of a plant cell showing how Turgor pressure (TP), Osmotic pressure (OT) and Wall Pressure (WP) are related. Turgor Pressure (Plant water relations, 2008). Results % Change = Change in Wt (g)/ [Wt (g) before –Wt (g) after] X 100 Table.1 Show changes in mass of potato tissues in varying salt concentrations. Fig.2 shows a graphical representation of trends in reduction of potato weight against solution concentrations in both experiment 1 and 2. Time of Experiment. Experiment 1 (10.00 Am) Experiment 2 (10.30 Am) Concentration (M) 0.05 0.1 0.15 0.0 0.2 0.4 0.6 0.8 1 Weight before (g) 0.77 0.81 0.78 1.67 1.57 1.89 1.79 1.97 1.95 Weight after (g) 0.81 0.83 0.78 1.91 1.55 1.49 1.27 1.51 1.44 Change in weight (g) 0.04 0.77 0 0.24 -0.02 -0.4 -0.52 -0.46 -0.52 % change 5.2 2.5 0 14.4 -1.3 -21.2 -29.1 -23.4 -26.2 Carrots Time of Experiment. Experiment 1. (10.10 Am) Experiment 2. (10.20 Am) Concentration (M) 0.0 0.2 0.4 0.6 0.8 1 0.05 0.10 0.15 0.25 0.30 Weight before (g) 1.07 1.43 1.26 1.06 1.23 1.45 0.72 0.69 0.59 0.76 0.74 Weight after (g) 1.07 1.40 1.09 0.87 1.00 1.22 0.73 0.70 0.59 0.73 0.70 Change in weight (g) 0.06 -0.03 -0.17 -0.17 -0.23 -0.23 0.01 0.01 0 -0.03 -0.04 % change 5.6 -2.1 -13.5 -16.3 -18.7 -15.9 1.4 1.4 0 -3.9 -5.4 Table.2 shows results of immersing carrot tissue in different strengths of salt solution. Fig.3. Is a graphical display chart of trends when carrot tissue lost mass in salt solution. Swedes Time of Experiment. Experiment 1. (10.20 Am) Experiment 2. (10.25 Am) Concentration (M) 0 0.2 0.4 0.6 0.8 1 0.05 0.1 0.15 0.25 0.30 Weight before (g) 1.46 1.46 1.47 1.47 1.43 1.46 0.54 0.52 0.55 0.63 0.63 Weight after (g) 1.53 1.47 1.32 1.22 1.20 1.23 0.57 0.53 0.56 0.65 0.63 Change in weight (g) 0.07 0.01 -0.15 -0.25 -0.23 -0.23 0.03 0.01 0.01 0.02 0 % change 4.8 0.7 -10.2 -17 -16.1 -15.8 5.6 1.9 1.8 3.2 0 Table .3 is a display of results on an experiment on Swedes tissue in salt solutions. Fig.4. This chart shows trends in mass loss by Swedes tissue in salt solution. Discussion Data Analysis as displayed on the graphical charts in Figures 2, 3 and 4. Show the various trends in weight loss by the experimental tissues. From these charts, there are points of similarity between the results of potatoes, Swedes and carrots, in the series of 0.3M up to 0.4 M. This is an indication that decrease in mass has reached optimal level. After this point, swedes and carrots start to show a marked increase in mass from concentrations of 0.4M up to 0.8M. In contrast, potatoes show a slight increase in mass which then declines as salt solution concentrations increases towards 0.8M. According to the results, the disc pieces reduced in mass as solute concentration strength increased. This is because the osmotic potential was favouring movement of water molecules out of the cells to the region with lower water concentration. The presence of solutes in the solution is responsible for lowering the water concentration outside the pieces. It is for this reason that the sample pieces reduced in their mass since water moved out of them via the semi permeable membrane. The variables that were determined in this experiment are solute concentration in the solution and duration of time spends in the solution. The temperature and volume of the solution were maintained constant. Generally, living tissues immersed in solutions of pH 3.2 or lower will take little water in, then later display increased rate of water loss until they become flaccid (Pearsall & Ewing, 1926).The rate at which this process takes place depends on the range of solution concentration and type of tissue. However, this process does not occur in dead tissues as shown by the control experiment results. Therefore, it is conclusive to say that the varying composition of living cell sap and cytoplasm is responsible to the rate at which water is lost (Pearsall & Ewing, 1926). Subsequently, comparing observations and results of this experiment, they can be liken to other research studies, for example presence of excessive soluble salts in soil causes salinity, this is a factor that poses a major challenge to farming because crops develop salt stress and lowers the yield (Munns, 2002). Salt stress is a situation where concentration of salt is increased to that level that can lower water potential. A report by Swapnat (2000), show that salt tolerant plants have unique characteristics in that they accumulate sodium salt in their vacuole. This characteristic reduces the cell sap osmotic potential by lowering the cytoplasmic sodium level hence avoids salt stress (Swapnat, 2000). Conclusion and recommendations Results of this experiment in comparison other studies by Pearsall and Ewing give a clear indication on how different plant tissues are adapted to different physiological processes. The cell sap and cytoplasm constitute the protoplasm of living cells. In this protoplasm, there are proteins with differing isoelectric points that are responsible for survival of certain species of plants under changing concentrations in the surrounding medium (Pearsall & Ewing, 1926). It is possible that these proteins were responsible for swedes and carrots to grow as the salt solution concentrations increased while the potato tissues were dying. We therefore, Reject the Null hypothesis and note that there is a difference in the composition of cell cytoplasm and Sap between Potatoes Swedes and Carrots. Based on the results of this experiment, it is possible to give recommendation to farmers on how to solve the problem of salinity and salt stress in crops because it has been established that, presence of salts in the cytoplasm affects physiological aspects of the plant while presence of salt in the vacuole has no effect. (Swapnat, 2000). References Munns, R 2002, ‘Plant, Cell and environment’, Comparative physiology of salt and water stress.Canberra ACT 2601, Australia. 239-250. Retrieved on April, 09, 2009 from Pearsall, W, H and Ewing, J 1926, The absorption of water by plant tissue in relation to external hydrogen-ion concentration. Retrieved on April, 09, 2009 from Plant water relations 2008, Absorption and movement of water, Retrieved on April, 10, 2009 from Swapnat, T, S 2000, Generation of variability for salt tolerance in rice using tissue culture techniques. Cochin University of science and technology. Retrieved on April, 09, 2009 from Read More