Utilization of Bright Field Microscopy & Electrical Conductivity for the Determination of Osmotic Potential

LA B 2 Assignment Worth: 1.5% (marked out of 15) Due: October 15 th,2020 Data Analysis 1. Using the formula in the lab manual for your calculation, prepare aproperly formatted table which includes values for sucrose, NaCl, and CaCl 2using the following headings: average isosmotic threshold (determined from the provided data on Nexus, no standard deviations required), osmotic coefficient (ϕ), #ions/molecule (V), and the osmotic potential (ΨO). The following values of ϕshould be used: sucrose = 1.02, NaCl = 0.93, CaCl 2= 0.86. Include a sample calculation below your table. (3 marks) 2. Using the values from your table from data analysis 1, what is the osmotic potential of the red onion cell? (0.5 marks) 3. Convert the electrical conductivity data to osmotic potential, and use these values to create a graph versus the concentration of the solutions. All three solutions should be included on the same graph in a properly formatted figure. A best-fit straight line, forced through zero, must be included for each solution. (3 marks) 4. Use your answer from data analysis 2and the line equations from data analysis 3to determine the concentration of each solution which is isotonic to the cell. (1.5 marks) Questions 1. Identify the chemical nature (electrolyte or non-electrolyte) of each of your three solutions. (1 mark) 2. Why do electrolytes require adecreased concentration of solutes in order to reach the isosmotic threshold? Why are these concentrations not the same for all electrolytes (Hint: there are two reasons) (1.5 marks) 3. Why does deplasmolysis occur over time? Why would ittake longer for deplasmolysis to occur for some solutes as compared to others? (1.5 marks) 4. Did your electrical conductivity data result in determining the same isotonic concentration as observed for the isosmotic threshold data? Explain any discrepancies based upon the chemical nature of the solutes used. Your answer should address exactly what is being measured by each method, and how this relates to the cell. (3 marks)