1. 1 Putting photosynthesis to the test Applying tools to the question at hand How?Why?

2. 2 Goals & Purpose To test a common claim from textbooks To build and understand tools you’re working with recall: otherwise, it’s simply not science. It’s magical mumbo- jumbo To generate meaningful data that allows drawing of conclusions. And to draw them

3. 3 Theory

4. Looking at a leaf, what would you hypothesize would be the most effective wavelengths for photosynthesis? (what is your mechanism? Your WHY?) 4

5. 5 Making it so... How could we use last week’s tools to address the question Hypothesis: Photosynthesis in (green plants) is more effective at the ends of the spectrum than in the middle BECAUSE…

6. 6 Photosynthesis: Review

7. 7 Team efforts Grounds 1 & 4: liquid permitting red light (low absorbance @ 630 and 660 nm) Groups 2 & 5: liquid permitting green light (low absorbance @ 590) Groups 3 & 6: liquid permitting blue light (low absorbance @ 350 and 430 ALL: Make enough to share (yours + 2 others) Final experiment in 20 ml, so...

8. 8

9. 9

10. 10 Dance of the Buffers Ca ++ +____ -- => precipitate Thus, TWO 10x buffer components Add either one LAST lest you lose a solid Add CaCl2 FIRST Add NaHCO3(without CaCl2) AFTER the dyes THEN add enough water to get to 80mL

11. 11 What’s the experiment look like? Need to place disks in at same time? What do you time? Does volume in the beaker matter? Does concentration matter? How can you make comparisons valid?

12. 12 Design

13. 13 Designer helper Plotulence: in Lab 11 Folder on desktops ‘New Table’ Enter data Use sliders to set concentration/dilution What calculation is the program performing? The ‘slider’ numbers on the side correspond to end concentration of that dye color in your final solution Check with other group of same color

14. It’s a “Helper” ‘Start Table’ Enter your data Use sliders Red = 630 and 660 Blue = 350 and 430 Green = 500 and 590 Absorbance no more than 0.2 at your wavelength!!!! Your data are based on a “1X” Solution. Dyes in back are 10X Dilute your dyes with distilled water

15. Mix It Remember there are TWO ‘buffers’ Compare your plan to other group’s Mix your color Trade ‘colors’ with your friends; collect all three!!!! Get your disks Float ‘em

16. 16 All’s fair... if you make it that way Does it matter if amount green (and other wavelengths) available light of the ‘green tube’ is similar to amount blue (and other) available light of the ‘blue tube’ What should we do about it?

17. 17 Comparing curves Generate smoothed curves based on your spec readings Cut them out; weigh them* What does the resulting number represent? How should it be used? *Curve parameters: Y-axis, set 4th major line from bottom as 2.00 absorbance units X-axis, each major line is 100nm, plot 300->700 nm

18. 18 Execution

19. 19 Make it so Groups 1, 3, 5 will exchange so everyone has a red- allowing, green-allowing & blue-allowing tube 2, 4, and 6 will do the same Each group shall write a lab report on their data

20. 20 Interpretation

21. 21 Closing discussion Did we find what we expected to find? Are there stones left unturned (unexamined assumptions in our experiment)?

22. 22 Represent! How should you take the differences in your graphs (the weights) into account? Suppose you had red dye, graph-weight 3.0 g, and that floated in 5 minutes blue dye, graph-weight 2.0 g, with flotation in 7’ Green dye, graph-weight 3.5 g, with flotation in 11 min How would you calculate the adjusted speed-of-flotation?

23. GIVE BACK QUIZ 9 Tonight’s quiz (Quiz 10) is a take home quiz If you received less than an ‘A’, I want you to write me a paragraph explaining where you went wrong in studying for Quiz 9 and how you plan to improve this for the future If you received a 90 or higher, explain how you prepared effectively for this quiz 23

24. 24 Homework a lab report in my dropbox featuring... Sound Logic & Presentation Complete sentences Correct spelling Elements in correct places (methods, results, discussion a lab report in my dropbox featuring... Sound Logic & Presentation Complete sentences Correct spelling Elements in correct places (methods, results, discussion

25. 25 Biology, the Dynamic Science, Vol. I Russell, Wolfe, Hertz, Starr