Goals Consider implications of plants being ‘green’ Use O2 creation as a measurement of photosynthesis Test a common claim from textbooks

Here’s an assertion… Can we test this? Photosynthesis in (green plants) is more effective at the ends of the spectrum than in the middle

HOW can we test it What did we do with leaves last week? –Leaf assay –Graph of absorption spectrum How did that happen? How can you make your data meaningful?

To dark (Calvin) cycle to make glucose

ALL: Make enough to share (yours + 2 others) Getting Started Absorbance at ‘your’ wavelengths should be LESS THAN 0.2 And no greater than ~2.0 at other wavelengths

Groups 1 & 4: liquid permitting red light Groups 2 & 5: liquid permitting green light Groups 3 & 6: liquid permitting blue light ALL: Make enough to share (yours + 2 others) No less than 0.2 at ‘your’ wavelengths; no greater than 2 at others Getting Started

Buffers Ca++ and PO4--  precipitate So, TWO different 10X buffer components Add ONE of the them last or get a solid

What will it look like? Need to place disks in at same time? What do you time? Does volume/beaker matter? Does concentration matter? How can you make comparisons valid?

Consider… What is the mechanism by which we are ‘removing’ some wavelengths of light? Implications for volumes of beakers? Consequences if red sits waiting while you work with blue and green

Use ‘Plotulence’ to develop your dye cocktail Sliders indicate how much more concentrated than last week All ‘mixers’ are 10X – if you make 100 mL, how many mLs are the two ‘buffers’? Water? Check with other group of same color We’re not making artificial hearts or sending a probe to Mars

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

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

What if one ‘color’ is darker? Test your color using specs Graph your data using smoothed curves Cut out the graph ABOVE line Weigh it; record it; compare it What does that number represent? Y-axis:4 th major line from bottom as 2.0 abs X-axis: each major line is 100nm; plot nm Give your graph weight to ‘sharing’ groups!

What Now? Did you find what you expected? Stones left unturned? Differences in graph weights? –Red, graph 3g, floated in 5 min –Blue, graph 2g, floated in 7 min Adjusted speed? This is a critical part of your experiment. Failure to explain and deliver this calculation = loss of points on write up