Photosynthesis II Lab Report Courtney McCorstin Wednesday 2 30 TA Alex Pilote Lab Partners Harley Paul Abby Howell Kathryn Bosshardt Fall Semester Introduction The purpose of this experiment was to determine the oxygen concentration and the photosynthetic rate of two different plants leaves a bean plants vs collards Photosynthesis is the process in which plants change the energy in sunlight to kinds of energy that can be stored for later use The plants convert the energy from the sunlight to sugar and cellular respiration then makes this into ATP which gives all living things their energy It is important that we continue to study this process because once we fully understand these processes like photosynthesis and photorespiration we will have the ability to alter them and make them more efficient Research on which agricultural plant is more efficient can demonstrate how to produce new crop strains that will make better use of the sunlight s energy Some researchers have found that oleaginous microalgae have a potential nextgeneration feedstock s for biofuels However they seem to produce lower amounts than expected so some mutations and genetic engineering tools were required to make the microalgae more resourceful Hu et al A company is trying to establish which plant would be the best fuel source This is determined by how efficiently each plant is able to turn light energy into biomass or more simply how quickly they are able to photosynthesize The companies would need to continue to test different types of plants and compare the data in order to determine which plant was best to use for biofuels Once they have determined what plant would be best used and then they can begin to enhance its effects by producing a new strand of crops Hu et al Hypothesis The collards leaves are slightly wider and bigger in surface area than the bean plants leaves There is more surface area over which photosynthesis can take place in the collard plant Because of this I predict that the photosynthetic rate will be greater in the collard plant than in the bean plant This logic is further exemplified by the study that researchers conducted on the different layers of greenhouse cucumber canopy This study showed that even though the upper canopy plants were closer to the light they did not photosynthesize as well as the lower canopy plants which had a greater surface area The conclusion was that if not taking into other outside factors increasing the leaf area should improve wholeplant photosynthesis Chen et al Method This experiment required the use of a computer program called PhotoLab This program allowed us to graph the oxygen content vs time and the light sensor vs time of each leaf We first had to set up our workstation which had a contraption for the leaf that was connected to the computer We first positioned the bean plants leaf in the lower surface of the leaf chamber and sealed it inside the chamber Then we placed 200 mL of tap water on top of the leaf chamber 12 cm under the light fixture to absorb heat After setting it up we started the PhotoLab program to collect data on the O2 of the leaf chamber We connected a gasbag filled with our breath which is essentially CO2 and squeezed it so that there was more CO2 and less O2 Once the O2 has leveled off which is usually around 3 minutes switch on the lamp and change the water after 15 minutes Collect this data for about 20 45 minutes until the O2 concentration in the chamber is steady The surface area of both leaves have to be found so once the experiment is done be sure to leave it in the leaf chamber Surface area of the leaf is found by counting all the intersecting lines that land exactly on the leaf Then I multiplied that by 0 5 and count all the squares that are filled in in the leaf After I added that up and divided by 4 I saved these results along with the graph from PhotoLab and repeated this same process for the collard plants leaf Once I had the graph and surface area of both leaves I was able to find the photosynthetic rate mol O2 m min Results After all the data is collected we made two graphs one for the bean plant and one for the collard plant From this we made a line of best fit by graphing the yvalues and slopes that we calculated To find the photosynthetic rate we used the formula 0 047 x Y Value surface area The surface area of the bean plant was 24 5cm2 while the surface area for the collard plant was 27cm2 The rest of the data was acquired from the PhotoLab program shown below Bean Plant Data Interval M slope O2 min Photosynthetic y value Selected min Rate umol m2 sec Initial Phase Middle Phase Final Phase umolO2 m2 min 0 05726 0 086 0 116 29 85 44 83 60 49 14 76 0 6696 0 013 Collard Plant Data Interval M slope O2 min Photosynthetic y value Selected min Rate umol m2 sec Initial Phase Middle Phase Final Phase umolO2 m2 min 0 060595 0 0744689 0 06157 34 81 42 78 35 37 1 905 0 1621 0 2002 Calculations of the photosynthetic rate Bean plant Surface area calculation 95 intersections 6 0 5 4 24 5 cm 2 Initial Phase 0 047 x 29 85 24 5 0 05726 Middle Phase 0 047 x 44 83 24 5 0 086 Final Phase 0 047 x 60 49 24 5 0 116 Collard plant Surface area calculation 100 intersections 16 0 5 4 27cm 2 Initial Phase 0 047 x 34 81 27 0 060595 Middle Phase 0 047 x 42 78 27 0 0744689 Final Phase 0 047 x 35 37 27 0 06157 After graphing our values and using the line of best fit we were able to find that the bean plant has a higher photosynthetic rate than the collard plant in the final stage The photosynthetic rate for the bean plant was 0 116 umolO2 m2 min while the collard plant was only 0 06157 umolO2 m2 min Conclusion These results disproved my hypothesis that the collard plant was going to have a higher photosynthetic rate than the bean plant I assumed that because the collard plant had greater surface it would be able to photosynthesize better but that was not necessarily true I think to fully understand how two different plant leaves photosynthesize more tests need to be executed For example the experiment with the greenhouse cucumber canopy yielded that the bigger surface area photosynthesized better however our experiment said differently Chen et al Works Cited Hu G Fan Zhang L Yuan C Wang J et al 2013 Enhanced Lipid Productivity and Photosynthesis Efficiency in a Desmodesmus sp Mutant Induced by Heavy Carbon Ions PLoS ONE 8 4 e60700 doi 10 1371 journal pone 0060700 Chen Tsu Wei Henke Michael de Visser Pieter H B Buck Sorlin Gerhard Wiechers