You have brought your Osmosis laboratory data with you. The calculations and graphs are daunting, but in this lecture period I hope you will be able to get the crunching work done so we can get on with understanding the biology of what went on in your project.
I have prepared a Microsoft Excel worksheet on the computers in Goddard 114a. This worksheet will do all the "dirty math work" for you as well as the graphic arts. You will need to put your Table 1, Osmometer Value, and Table 3 data into the appropriate cells in the worksheet. The [tab] key will take you to each cell where you need to add data.
Now that your data are entered, you need to print out the three graphs. Double click each graph. You can click the zoom box (upper right corner) if you want to see the graph at full screen size. From the File menubar, drag down to Page Setup. Then click on the Footer button. In one of the three windows, type your group name(s). You can then click OK until all the dialog boxes are gone. Then hit command-p to print the graph. Repeat this process for each of the three graphs.
With the graphs in hand, you need to draw smooth curves among the points for the three curves in the Hofler diagram and the two curves in the last graph.
In the last graph (2b), find a value that represents the equilibrium relative cell volume. Then find the initial relative cell volume. The half-time is found by drawing a horizontal line to the curve from a relative cell volume half-way between the initial and equilibrium relative cell volumes. The three-quarter time is found by drawing a horizontal line to the curve from a relative cell volume half-way between the half-time relative cell volume and the equilibrium relative cell volume.
The slopes of the curve at the initial time, half time, and three-quarter time for both curves are determined from a tangent line at each of the six points. The slope represents the rate of water transport (Q). You should enter these slopes in the first column of the final Table 5.
In the second column of Table 5, enter the relative cell volume at each of the three times for both curves.
Look up the water potential using the relative cell volume and the correct curve in the Hofler diagram.
The computer will do the rest for you. Print out the spreadsheet with all the calculation results to include with the three graphs for your amplified abstract.
Try to get the meaning of the exercise from reading through it. Dr. Koning will make a short presentation using one set of data from the class.
Go back to the Course Schedule.