CHS A.P. Biology
AP Biology Photosynthesis Lab3009900283210No LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO2100200300400500600700800900100011001200130014001500160017001800190000No LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO21002003004005006007008009001000110012001300140015001600170018001900Data:LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO21002003004005106217418529541065117612861398141081591610171819307657547625Blue LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO21002003004005006117118329441055116512761377148815991610917918101900Blue LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO210020030040050061171183294410551165127613771488159916109179181019Red LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO21002003004005006007008119221022113312341344144515561666176618771988Green LightTIME(min)# discs floatingw/CO2# discs floatingwo/CO21002003004005006007008009001010111112111322142215321633174318441954Analyzing DataTo make comparisons between experiments, a standard point of reference is needed. Repeated testing of this procedure has shown that the point at which 50% of the disks are floating (the median or ET50) is a reliable and repeatable point of reference. In this case, the disks floating are counted at the end of each time interval. The median is chosen over the mean as the summary statistic. The median will generally provide a better estimate of the central tendency of the data because, on occasion, a disk fails to rise or takes a very long time to do so. A term coined by G. L Steucek and R. J Hill (1985) for this relationship is ET50, the estimated time for 50% of the disks to rise. That is, rate is a change in a variable over time. The time required for 50% of the leaf disks to float is represented as Effective Time = ET50.Graph your data for the experimental group. Determine the ET50?for your leaf disks and determine the ET50?for your data.Graph:Without CO2With CO2Assessment:1. How can the rate of photosynthesis be measured?2. Where in the cells of the leaf do you find air spaces?3. What is the function of the stoma?4. What will happen if you remove the air from these spaces?5. How will air return to these spaces?6. List any factors that you think may affect the rate of photosynthesis. Consider environmental factors that you could manipulate during the lab.7. What was the function of the sodium bicarbonate in this experiment?8. Explain the process of carbon fixation.9. Explain the process that causes the leaf disks to rise.10. Which trial worked the best? Explain.11. What was the purpose of using water/soap solution for the experiment?12. What is the effect of darkness on photosynthesis? Explain.13. If we were to boil the leaf disks, what kind of results would you expect? Explain.14. How does light intensity affect the rate of photosynthesis?15. How does light intensity and the rate of photosynthesis relate to the position of the sun, both during the day and during the year? ................
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