Effect of color on photosynthesis rate

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Effect of color on photosynthesis rate

  1. 1. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ Carbon water glucose oxygen dioxide Safe Sangthongsuk March 8, 2010 IB BiologySLp.4 Effect of Color on Photosynthesis Rate Introduction Lightis the mostimportantsource of energythatsustainsall livesineverycommunitythus,the processthat turnslightintoenergyisextremelyimportanttoo. Photosynthesisisaprocessthatconverts carbon dioxide intoorganiccompoundsespeciallysugarusingsunlightenergy. The chemical reactionof photosynthesisisasfollows: Photosynthesishappensintwostages.The firstone, chlorophyll inplantscapture energyfrom sunlightthenitisconvertedtochemical energy, storedtemporarily inATPandNADPH.Inthe second stage,energy inATPand NADPHcontrols the formationof organiccompoundslike sugarbyusingup carbon dioxide. The processmostoftenoccursinplantsbutalso infew otherorganismslike algae, phytoplanktonandsome bacteria.These organismsare calledautotrophsorproducers, individualsthat can produce theirownfood.Consequently,otherorganismslike heterotrophsorconsumers rely on plantsforenergy. There are manyfactors that can affectthe rate of photosynthesis.Itincludessubstrate concentration,temperature,pHlevel,lightintensity,leaf type,andcolor of light.Thisinvestigationwill be examiningthe mosteffective colorof lightonphotosynthesisrate. The wavelengthof light determinesitscolor. Visible lightisone small partof the electromagneticspectrum. Visiblelightwith longwavelength, the colorisredder.Likewise the shorterwavelengthsare towardsthe violetsideof the spectrum. Figure 1 belowshowsthe visiblelightspectrumandalso expectedgraphof the effectof light wavelength onphotosynthesis. Figure 1: The expectedgraphof the effectof coloron photosynthesis.
  2. 2. Design Research Questions What color(s) of lightismosteffectiveincarryingoutphotosynthesis? Variables The independentvariable forthisexperimentisthe 4differentfoodcoloring;red,green,purple, and blue.Inadditionthere will be anothercontrolledcolorwhichisabeakerwithoutanycoloror clear. The dependentvariable will be the rate of photosynthesisaffectedbythe different coloredlight.The controlledvariablesandthe methodforcontrollingare shownin Table1. The most importantvariables that neededtobe controlledare the factorsthataffectsphotosyntheticrate whichare substrate concentration,temperature,pHlevel,lightintensityandleaf color. Table 1: ControlledVariablesand Method Controlled Variables Method of Controlling Substrate Concentration 2% or 10g of NaHCO3 (SodiumBicarbonate) Temperature An aquariumwithwaterwasplacedinfrontof the beakersfor the waterinside ittoabsorb the heatand lettingonlyinfrared (light) throughtothe beakers. pH Level All solutionhasapH of 7. LightIntensity Lightwas at the most intense level, 770 lux. The distance was keptthe same at 50cm fromthe lightand the aquarium. Leaf Type and Color All leaveswere of the same speciesandall were healthygreen Materials  2500mL of water; 500 for eachcolor  Four foodcolors:red,violet,blue,green  50g of SodiumBicarbonate  Five 1000mL Flasks  15 100mL Beakers  One 250mL GraduatedCylinder  One 100mL GraduatedCylinder  About20 Healthy,greenleaves  Two Thermometer  Aquariumfilledwithwater  Spotlight  Stopwatch  StirringRod  Medicine Bowl  Syringe  PaperPuncher  Disposable Piped  LightSensor/LoggerPro Procedure Firstly,the solutionsare neededtobe made.Measure 500mL of waterintothe five flasks.Use disposable pipedtodropthe foodcolorintothe four flasks(the lastone isthe controlledwhichhasno color,clear) as follows:2dropsof violet,3dropsof red,2 dropsof blue,and3 dropsfor green.Mass and mix 10g of SodiumBicarbonate intothe five flasks.Stirthe solutionsineachflaskuntil everythingis properlydissolved. Measure 100mL of the clearsolutionandpourthe solutionsintothe 100mL beakers. For the clearsolution,repeatthissteptwomore time.Thenforthe otherfourcoloredsolutions,repeat the previoustwostepsthree times.Atthe endof this,there will be 15beakers;three 100mL beakersfor each color. The coloredsolutionacts as a colorfilterthatchangesthe color of lightwhenitshinesonthe leaf discs. It isalsoveryimportantthat these beakersshouldbe sittinginthe darkuntil everythingis ready. Table 1: Showsthe controlledvariablesandthe methodof controllinginthisexperiment
  3. 3. Afterthe solutionsare prepared,move ontogetthe leavesready.Use the paperpuncherto cut out small discof leaves,assoonas the leavesare cut outimmediatelyplace theminmedicinebowl with water. Each trail needsmore than50 leaf discsforthe 5 beakerssointotal,more than 150 discsare neededincase the leafsdonotdeoxygenize.Poureverythinginthe medicinebowl inside asyringe but letout some waterif neededtoleave some airspace inthe syringe.Suckoutall oxygenbyturning it upside down;put a thumboverthe orifice sono airenters.Keeppullingonthe pumpuntil all diskssink. Pourthemback out intothe medicine bowl. Setup the experimentbyplacinganaquariumona table thenfill ittoabouthalfwaywithwater. Thensetthe spotlightatabout50cm away fromthe aquarium,showninFigure 2. The aquariumand the waterfunctionstocontrol the temperature,the waterwill absorbthe heatandletonlylightthroughto the beaker. Place the 5 beakers,one fromeachcolor,behindthe aquarium.Tobeginthe experiment, put 10 leaf discsintoeachbeaker.Itis veryimportantthatthe room isdark. Start the time as soonas the spotlightisturnedon,recordthe time whenleaf discsrise upto the topof the solution. Also remembertotake the temperature everyonce inawhile tomake sure thatit isthe same throughoutthe test. SpotlightAquarium 50cm Aquarium Beakers Figure 2: The set upof the aquarium(tocontrol temperature) andthe spotlight(tocontrol the lightintensity) Figure 3: Setup of the beakers,picture takenbehindthe beakers.
  4. 4. Data Collection Table 2: Time (inseconds) Each Leaf Disc Rise and itsAverage from Trial 1 Red Green Blue Violet Clear 440 425 554 446 345 441 426 637 491 351 465 465 832 604 353 532 466 971 605 361 540 496 972 733 377 564 502 1115 792 408 577 585 1118 805 435 632 607 1177 829 450 659 641 1229 841 460 659 658 1261 1011 489 Average 550.9 527.1 986.6 715.7 402.9 Table 3: Time (inseconds) Each Leaf Disc Rise and itsAverage from Trial 2 Red Green Blue Violet Clear 258 601 304 432 261 366 607 441 492 398 363 688 511 500 407 585 691 585 538 423 597 697 703 542 480 625 709 732 550 486 635 716 916 552 514 707 751 1242 573 518 709 751 1266 669 526 826 751 1343 700 530 Average 567.1 696.2 804.3 554.8 454.8 Table 2: The firsttrial of the time eachleaf disctakesto rise to the surface foreach colorand the average foreach color Table 3: The secondtrial of the time eachleaf disctakesto rise tothe surface foreach colorand the average foreach color
  5. 5. Table 4: Time (inseconds) Each Leaf Disc Rise and itsAverage from Trial 3 Red Green Blue Violet Clear 183 199 185 362 192 493 215 313 363 203 493 294 390 363 310 494 384 432 460 310 518 475 433 431 354 554 588 491 431 379 740 602 522 537 468 751 694 522 537 468 752 719 742 596 468 754 727 906 600 477 Average 573.2 489.7 493.6 468.0 362.9 Overall Observationsduring the Experiment:  If the mixedsolutionissittingstill foralongwhile,there wasresidue atthe bottom of the flask whichmeansthat the solutionisnotproperlydissolved  These leaveshave fibersosometimestheywere stucktoeachotherwhentheywere rising  Airwas takenoutof mostleaves,there were some thatstill floatatthe surface but the problem was solvedbyaddingextraleaf discsthatsinks. Data Processing Table 4: The thirdtrial of the time eachleaf disctakesto rise to the surface for eachcolor andthe average for eachcolor Figure 4: The graph showsaverage time thateachleaf discstookto photosynthesize inTrial 1. The expectedgraphwouldshowapositive correlation.
  6. 6. Note:The uncertaintiesforthe rate of photosynthesisgraphwere calculatedbythe T-Testfrom www.graphpad.com.The T-Testwasusedtofind the standarddeviationwhichwasusedfor uncertaintiesandto see if the uncertaintiesare significanttothe data.The resultof the significanceof the data are as follows:the datapairsof clear andred, redand blue,greenandviolet,andblue and violetare verysignificantwhereasthe datapairsof redand green,redandviolet,andgreenandviolet are notstatisticallysignificant. Sample Calculations 1. Average Time for each color, each trial (sample datafromred,trial 1) = sumof the times/numberof trials = (440+441+465+532+540+564+577+632+659+659)/10 = 550.9 2. Average Time for each color, all trials (sample datafromred) = sumof averagesforeachcolor fromeach trial/numberof trials = (550.9+567.1+5730.2)/3 = 563.7 3. Rate of PhotosyntheticReaction (sample datafromclear) = 1/average time inseconds = 1/563.7 = 0.00177 Figure 5: The graph showsthe rate of photosynthesisaccordingtothe colorof the solution orderingfromthe average colorreactionwiththe fastestrate to the one withthe slowestrate.
  7. 7. 4. Uncertaintiesofthe Rate of PhotosyntheticReaction(sample datafromclear) Percent of Uncertainties = (StandardDeviation/Sumof the Times)*100 = (90.53/4372)*100 = 2.1% Uncertaintiesof the Rate = (Rate of Photosynthesis)*(Percentof Uncertainties/100) = 0.00229*0.021 = ±0.000048 Conclusion The data in Figure 4 demonstratesthe average time thatleaf discsindifferentcoloredsolutions tookto rise to the surface.Accordingto thisfigure,the orderof the time fromthe leasttime tothe most time isclear,green,red,violetandblue. Since the colorof the solutionsare orderedaccordingtothe expectedtime withthe colorthattakeslesstime tothe mosttime,the expectedgraphwouldhave a positive correlation.FromFigure 4,itisveryclose to the expectedgraphinfactit wouldfitanexpected graph if green hadthe highestaverage time. The resultsshowninFigure 5 showsthat the fastestphotosyntheticrate isthe clear solution, 0.00229, as expected.The nextfastestreactionisthe redsolutionwiththe rate of 0.00177 thenclose to the red solutionare greenwiththe rate of 0.00175 andvioletwiththe rate of 0.00173. The slowestrate of reactioninthisexperimentisthe blue solutionwiththe rate of 0.00131. Though the resultsseems like itdoesnotmake sense,itisonlythe rate of greenthat messesupthe experiment.The expected orderof the rate fromfastestto slowestisclear,red,violet,blueandgreen.If the rate of greenwas the lowest,the resultof thisexperimentwouldhave clearlymatchedthe expectedresult. Infact,Figure 4 is a fittingevidence thatprovesthatthe greensolutioncausesthe resultof the experimenttonotbe able to clearlyprovide evidence thatmatchesthe expectedgraph.Though,itcanbe concludedthat the overall trendof the resultforthe mostpart agreeswiththe expectedresult. The source of thiserrorthat putsthe rate of greensolutioninthe wrongorder isprobablyfromthe methodof mixingcolorswhichis discussedin Evaluations. Evaluations The biggestweaknessinthisexperimentwas probably the methodof recordingtime whenthe leaf discrises. Sometimesmanydiscsfromdifferentbeakersrise atthe same time whichmakesithard to getthe exacttime.Anotherweaknessisfromthe fiberinthe leaves.Some leafdiscsare stuckto each otherbecause theyare connectedbyfibers.Thiscouldhave accountedforsome inaccuracyinthe time takento rise foreach discsince one mightphotosynthesizefasterandif the otherisnot photosynthesizedyet,itwillbe pulleduptothe surface by the one stuck to it.The last problemisfrom the leaf discsthat wouldnotsink.There were some discsthatdidn’tsinkwhenplacedinthe beakerbut thisproblemwassolvedbyaddingmore leaf discsthatsinkintothe beakeruntil there are tensunken leaf discsat the bottom. Anothervery importantsource of erroris fromone of the tool,the foodcolor.Differentfood coloringhadverydifferentshade of color;some were lightandtransparentwhereassome werevery dark. The approach takeninthisexperimentwastoadddifferentamountof dropsof foodcoloringfor each colorand control insteadthe lightintensitybysettingthe maximumlux (illumination) usingthe lightprobe.Thislimitationmighthave affectedthe control of lightintensitysince some colorsmight have had more colorthan the other.A solutiontothisproblemisadifferentwaytovarythe color. One mightbe coveringthe beakerswithdifferentcolors.

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