Teacher's/Lecturer'sSheet
Printed:30.03.201715:19:11|P8011900
Thegreenleafpigment(ItemNo.:P8011900)
CurricularRelevance
AreaofExpertise:
Biology
EducationLevel:
Age14-16
Subtopic:
Photosynthesisand
respirationofcells
Topic:
Plants
Experiment:
Thegreenleaf
pigment
Difficulty
PreparationTime
ExecutionTime
RecommendedGroupSize
Intermediate
10Minutes
30Minutes
2Students
AdditionalRequirements:
ExperimentVariations:
Potplantofagreen-whitevariegatedivy
Keywords:
Chlorophyll,Photosynthesis
Taskandequipment
Informationforteachers
AdditionalInformation
Thepreviousexperiment(Experiment"Conditionsnecessaryforphotosynthesis")hasshown,thattheformationofstarchinthe
plant,theassimilationofcarbondioxide,canonlytakeplacewhentheplantisexposedtolight.Thisprocessisthereforealso
calledphotosynthesis(Grek:phos"light",synthesis"composition").Inthisexperimentthestudentsaresupposedtorealizethat
photosynthesiscanonlyoccurwiththehelpofthegreenleafpigment,whichconvertsthelightofthesunintoenergy.
Thegreencolouroftheleavesiscausedbyaclassofnaturaldyes,thechlorophylls.Themainfunctionofthechlorophyllsisto
absorbtheincidentlightofthesun,toconvertthelightintoenergyandtotransporttheenergy.Thisenergyisnecessaryto
buildstarchfromcarbondioxideandwater.Inthisreaction,whichtakesplaceinthesocalledreactioncentre,thechlorophylls
("specialpair")arealsoinvolved.
Whenplantsaremissingthegreenleafpigmentchlorophyll,sotheycannotrunphotosynthesis,thisiscausedinmostcasesby
ageneticdefectduetomutation.Forsomeplantspecies,thegreenleafpigmentisonlymissingincertainareasoftheleaves,it
comestotheappearanceofmulti-coloredplants.Oftentheleavesaregreen-whiteorwhite-yellowishpatterned.(Theyellow
andredcolorsarecausedbyembeddedcarotenoids.)Onespeaksofvariegation.
Forsomeplantsvariegationisnatural,asforexamplefortheclover,andthepatternscausedemphasizetheflower.Forother
plantsvariegationisrarelyorcausedbybreeding,asforexamplegreen-whitevariegatedivy.
HintsonSet-upandAction
Insteadofagreen-whitevariegatedivyyoucanalsouseotherplantswithvariegatedleavesforthisexperiment,suchas
breededspeciesofthetropaeolum,thelilyofthevalleyorthetulips.
Hazards!
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Teacher's/Lecturer'sSheet
Printed:30.03.201715:19:11|P8011900
Ethylalcoholiseasilyinflammable.Extinguishallflamesbeforehandlingit!
Wearprotectiveglasses!
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Thegreenleafpigment(ItemNo.:P8011900)
Taskandequipment
Task
Whatistheimportanceofthegreenleafpigment?
Determinewhetherlightistheonlyprerequisiteforphotosynthesis.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Equipment
PositionNo.
Material
OrderNo.
Quantity
1
Supportbase,variable
02001-00
1
2
Supportrod,l=600mm,d=10mm,splitin2rodswith 02035-00
1
3
Supportring,i.d.130mm,w.boss
37722-03
1
4
Wiregauzewithceramic,160x160mm
33287-01
1
5
GlassbeakerDURAN®,tall,100ml
36002-00
1
6
Petridish,d100mm
64705-00
1
7
Bottle,nar.mouth,100ml,clear,p.st
41101-01
1
8
Graduatedcylinder100ml,PPtransparent
36629-01
1
9
Graduatedpipette10ml
36600-00
1
10
Pipettor,bulb,3valves,10mlmax.
47127-01
1
11
Scissors,straight,pointed,l110mm
64623-00
1
12
Tweezers,straight,pointed,120mm
64607-00
1
13
Protectingglasses,clearglass
39316-00
1
Butaneburner,Labogaz206type
32178-00
1
ButanecartridgeC206,withoutvalve
47535-01
1
Iodinepotass.iodidesol.,250ml
30094-25
1
Water,distilled5l
31246-81
1
Denaturatedalcohol(spiritforburning),1000ml
31150-70
1
Additional
material
Potplantofagreen-whitevariegatedivy
Set-upandprocedure
Hazards!
Ethylalcoholiseasilyinflammable.Extinguishallflamesbeforehandlingit!
Wearprotectiveglasses!
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Placeavariegatedivypotplantinsunlightorilluminateitwithastronglightbulbforatleast3hours.
Afterthis3hoursexposure,detachoneofthegreen-whitepatternedleavesfromtheplant.DrawasketchontheResults
pageofhowthegreenandwhiteareasaredistributedontheleafsurface(Fig.1).
Fig.1
Setupasupportstandwiththesupportbaseandthesupportrod(Fig.2andFig.3),fixthesupportringtothesupportrodand
laythewiregauzeonit(Fig.4).
Fig.2
Fig.3
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Fig.4
Attachthebutaneburnertothebutanecartridge(Fig.5-6).
Fig.5
Fig.6
Filla100mlbeakerwithwaterandplaceitontothewiregauze.Usingmatcheslightupthebutaneburner,placeitunderneath
thewiregauze(Fig.7)andheatthewatertoboiling.
Fig.7
Droptheleafintothewaterinordertokillit(Fig.8).Afteraboutoneminuteturnoffthebutaneburner.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Fig.8
Filla100mmdiameterpetridishuptotwo-thirdswith96%ethylalcohol(ethanol).Makesureallbutaneburnersareswitched
offbeforeworkingwithethylalcohol.
Then,taketheleafoutofthewater-filledbeakerandtransferittothepreparedpetridish(Fig.9andFig.10).
Fig.9
Fig.10
Taketheleafoutoftheethylalcohol,rinseitwithdistilledwaterandpourLugol'siodinepotassium-iodidesolutionoveritina
100mmpetridish(Fig.11).
Fig.11
Afterhalfanhourdoasimplesketchofthedistributionofblue-violetandwhite-yellowishareasontheleafsurfaceinthereport.
Wastedisposal
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
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Theethylalcoholshouldbepouredintothecontainerforhalogen-freeorganicsubstances.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Report:Thegreenleafpigment
Result–Observations1(10Punkte)
Sketchthedistributionofgreenandwhitespotsintheleafarea.
Result–Observations2(10Punkte)
Describethedistributionofblue-violettandwhite-yellowishspotsintheleafarea.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Evaluation–Question1(10Punkte)
WhatisdetectedbymeansoftheIodine-potassiumiodinepotassium-iodidsolutionafterLUGOL?
Evaluation–Question2(10Punkte)
Comparethesketchshowingtheoriginalpositionsofthegreenareasontheleaftothesketcchshowingtheblue-violettareasontheleafafter
thetreatmentwithLUGOL'ssolution.Whatdoyounotice?
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
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Evaluation–Question3(10Punkte)
Inwhichpartsoftheleafhasstarchbeenformed?
Evaluation–Question4(10Punkte)
Theleafsurfacewasexposedtolight.Whatelseisrequiredfortheformationofstarch,i.e.theassimilationofcarbondioxide,inadditiontolight?
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201715:19:11|P8011900
Evaluation–Question5(10Punkte)
Therequirementsfortheformationofstarchintheplantarenowknown.Butwhichplantsarecapableofit?
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com