1. Photosynthesis

2. What is photosynthesis?

4. Photopigments absorb specific wavelengths Photosynthesis is most efficient using red and blue wavelengths

5. The stomata
Stomata control the diffusion of CO2, H20, and O2 in and out of the leaf
Plants open and close their stomata during the daytime in response to changing conditions:
- light intensity
- humidity
- CO2 concentration
The basic mechanism involves regulation of osmotic pressure

6. Photosynthesis on a global level…Where is it happening?
2005 NASA imaging
How can we measure photosynthesis rates and what sort of events can effect this?

7. Exercise 1: Measuring photosynthesis  Spinach leaf disks experiment

8. Exercise 1: Measuring photosynthesis  Spinach leaf disks experiment
Work in groups, but complete the worksheet individually
NaHCO3 + H2O  NaOH + H2O + CO2
Variable one: Concentration of dissolved CO2
0 % vs %
What variable must we maintain constant?
Hypothesis and predictions?
CONTROLS??

9. Exercise 1: Measuring photosynthesis  Spinach leaf disks experiment
Work in pairs, but complete the worksheet individually
NaHCO3 + H2O  NaOH + H2O + CO2
Variable one: Concentration of dissolved CO2
0 % vs. 0.2 %
What variable must we maintain constant?
Hypothesis and predictions?
CONTROLS??
 0.2 % CO2 placed in the dark. I will complete the control.

10. Exercise 1: Measuring photosynthesis  Spinach leaf disks experiment
Complete the worksheet individually
Graph your group’s results
Title your graph and include units!
Provide a caption for the graph
Calculate the rate of photosynthesis (# of disks floating / min)
Use the class data to answer the remaining questions
Units

11. Methods 1 2 3 Run your experiment for 20 minutes!
Punch out 15 disks Make them sink Record the # of disks
floating (every 1 min)
Run your experiment for 20 minutes!

12. Observe the stomata
Compare the top and bottom sides of spinach leaves. Is there a difference in the concentration of stomata? What is your hypothesis and what are your predictions?

13. Class Data
Group
CO2
No CO2 1 11 10 2 4 3 8 9 5 14 6
Total 49 33
Record your group’s calculated rate of photosynthesis (# of disks floating/min)

14. Chi-Square
CO2
No Co2
Observed 49 33
Expected 41

15. Stomata
Top
Down
Observed
Expected

16. In your lab write up results
Include graphs for your group’s data. (which graphs specifically?)
Include the table of the class data
Chi-square analysis of class data
Include a brief summary of results from all your graphs and the table.
You will discuss what the data mean in your Conclusion section.

17. Some pointers Affect vs. effect
Give actual data when describing the results
This study shows (not proves)
Data is plural, e.g., The data were graphed. Datum is singular
Diffusion and osmosis are based on the random movement of molecules. Water does not ‘want’ or ‘need’ to go…

18. Citation of resources
MLA Format Examples of unacceptable formats: 1) Dr. Cao’s powerpoints 2) Campbell book 3) Photosynthesis website