Investigation of the affect of salinity on Osmosis within Solanum tuberosum

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TABLE OF CONTENTS                                                                        page number

  1.  DESIGN                                                                                        

1.1   Defining the problem                                                                3-4

  • Focus / research question
  • Hypothesis
  • Background information / theory
  • Investigation Variables

1.2  Controlling Variables                                                                4

  • Treatment of Controlled Variables
  • Control Experiment

1.3  Experimental Method                                                                4

  • Materials
  • Risk Assessment
  • Method
  • Experimental Setup
  • Modifications to Experiment

2  DATA COLLECTION and PROCESSING                                                        5

2.1  Recording Raw Data                                                                5

  • Quantitative Data
  • Qualitative Data
  1. Processing Raw Data                                                                5
  • Statistical Processing - calculations
  1. Presenting Processed Data                                                        5-6
  • Result (s) table (s)
  • Graph (s)

3  CONCLUSION and EVALUATION                                                                6-7

3.1  Conclusion

  • Conclusion statement
  • Conclusion explanation

3.2  Evaluation Procedures                                                                7

  • Reliability
  • Limitations / Weaknesses / errors in Laboratory Investigation
  • Significance of weaknesses on experimental results
  1. Improving the Investigation                                                        7
  • Modifications to experiment

BIBLIOGRAPHY                                                                                8

APPENDIX A Risk Assessment and Laboratory Order Form

APPENDIX B Diagram set up

APPENDIX C Salt build up on the rim of measuring beakers

  1. Design
  1. Focus Question: What is the effect of different concentrations of salt solutions surrounding potato cells, Solanum tuberosum have on the osmosis of such cells.

Hypothesis:  If a 1 cm cube of Solanum tuberosum is covered with a high 40% concentration of sodium solution then the mass of Solanum tuberosum will decrease due to osmosis. However, when covered with distilled water the mass will increase as the Solanum tuberosum absorbs the water.


Osmosis is the diffusion of water across a selectively permeable membrane (Bell et al 2004).  More specifically, Osmosis involves the movement of water molecules from an area of high concentration of solution to an area of low concentration. As cell membranes allow water to pass through, any high concentration of solute relative to the cell can have a dramatic affect on the diffusion of water from the cell.  When a cell is placed in a hypertonic solution, containing a high concentration of any substance, the water easily diffuses out of the cell into the solute, in this case saline solution causing the cell to shrivel. (Biology Online, 2009) By placing the Solanum tuberosum in the 40% concentrated salt solution it is possible to predict that the water in the potato will diffuse into the solution, causing the cube of potato to decrease in weight. The opposite occurs when a cell is placed in a hypotonic solution of lower concentration, and the cell will absorb the water to the extent that it could possibly explode.

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However when the cube of Solanum tuberosum is placed in an isotonic solution, a solution with the same concentration of solute as the cell, water diffuses in and out of the cell as a constant weight resulting in no change of the cells mass. Considering the low amount of sodium found in raw potatoes it is possible to predict that when surrounded by the high concentrations of sodium water that the potato cube will shrivel and decrease in mass. Taking in to consideration the almost equal concentrations of sodium within distilled water and that of the potato it is also ...

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