bio 100l – lab 5 – photosynthesisrespiration(4)

7/30/2019 BIO 100L – Lab 5 – PhotosynthesisRespiration(4)

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BIO100L–Lab5–PHOTOSYNTHESIS&RESPIRATION

PHOTOSYNTHESIS

Plantsarecalled“producers”becausetheyarecapableofmanufacturingtheirownfood.

Mostoftheworld’sBIOMASS,themassoflivingmatterinagivenarea,consistsofplantmatter.

Plantshave4primaryrequirementsforgrowth:

- Water

- Sunlight

- SoilNutrients

- CarbonDioxide(CO2)

PHOTOSYNTHESISistheconversionoflightenergyintochemicalenergyintheformofglucose(sugar).

Itisarguablythemostimportantbiologicalenergyinreactionbecauseitisresponsiblefor

sustainingthemajorityoflifeonthisplanet.Plantsprovidetheoxygennecessaryforother

organismstometabolizetheirfoodintousableenergy.

Light

6H2O+6CO2C6H12O6+6O2

WaterCarbonDioxideGlucoseOxygen

Thecombinationof6watermoleculesand6carbondioxidemoleculeswhenenergizedby

lightinthechloroplast producesglucoseandoxygen.

TheenergystoredinglucoseisthenreleasedviaCELLULARRESPIRATIONprocesses.



CELLULARRESPIRATION

CELLULARRESPIRATIONconsistsofaseriesofmetabolicreactionsthatconverts

biochemicalenergyinto AdenineTriPhosphate( ATP)andthenreleaseswasteproducts.

ATP:principleenergysourceforreactionsinlivingcells

CellularRespirationisNOTthesameastherespirationhumansparticipatein–cellsdo

not“breathe”!

Cellularrespirationprimarilytakesplaceinthemitochondria.

Wewilldiscusstwokeytypes: ANAEROBICand AEROBICRESPIRATION.

ANAEROBICRESPIRATIONDOESNOT requireoxygentoproceed.

GLYCOLYSIS,ananaerobicprocess,breaksdownglucoseandreleasesenergythatiscapturedin ATPforlaterusebythecell

IfoxygenisNOTpresent,thetwoproductsofanaerobicrespirationare:

o LacticAcidinanimalscells

o Alcohol(Ethanol)insomemicroorganismsviaFERMENTATION

LacticacidandAlcoholrepresenttheincompletebreakdownofglucoseinthe

absenceofoxygenandproducesonly2ATPperglucosemolecule.

AEROBICRESPIRATIONDOESrequireoxygentoproceed

TheKREBSCYCLEcompletelybreaksdownglucose.Theenergyreleasedbyglucose

isthentransferredtotheELECTRONTRANSPORTSYSTEM(ETS).Thisresultsin

H2Oand36ATPperglucosemolecule.

Muchmoreenergyisproducedduringaerobicprocesses,hencethegreateroutputof ATPperglucosemolecule.

Justasplantsprovideoxygentonon-producerorganisms,theselatterorganismsprovide

plantswiththecarbondioxidetheyneedtomanufacturecarbohydrates.

C6H12O6+6O2 6H2O+6CO2+36ATP

Glucose Oxygen Water CarbonDioxide

Notethatrespirationisthereversereactionofphotosynthesis.

IMPORTANT:Plantsboth photosynthesizeandrespire.Videodemonstrationofcellularrespiration:

http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html



LEFT. Asimpledepictionofbothanaerobic and

aerobic cellularrespiration.

RIGHT.Anillustrationoftheconnection

betweenphotosynthesisandrespiration.



CLIMATECHANGE

The Earth’s climate has changed rapidly in the past few decades, with temperatures

increasinginaphenomenoncalledGLOBALWARMING.However,amoreaccuratetermisCLIMATECHANGE,asallsortsoffluctuationsareexpectedtooccur,includingincreased

stormactivity(e.g.,moreaggressivehurricanes),drierconditionsduringdroughtperiods,strongerfloodsduringwetseasons.

CLIMATE CHANGE is causedbyGREENHOUSE GASES that trapheat insidetheEarth’s

atmosphere(similartoagreenhouseforplants).TheGREENHOUSEEFFECThelpsregulatethe temperatureof the planet and facilitates life onearth. Without this mechanism, the

earthwouldbeextremelycold.

WaterVaporisthemostabundantgreenhousegas.

CO2 isthe second-mostabundantgreenhousegas, andthe onewehave the mostcontrolover.

Greenhousegasescreatedthroughtheburningoffossilfuels(e.g.,coal,oil,gas)areraising

thetemperatureoftheearthduetothehighconcentrationthatisenteringtheatmosphere

duetotheseactivities.

This graph is known as the

“KEELING CURVE”. Through

datatakeneverydayinMauna

Loa since the early 1960s, it

demonstrates that CO2

concentrations have beenrapidlyincreasingoverthelast

50 years, with an initial

concentrationat315partspermillion (ppm) and a current

concentrationof~390ppm.

Theannualfluctuationsshown

in the graph demonstrate

changes in photosynthesis(whichinvolvestheuptakeofCO2)throughouttheyear.Declinesoccurinsummer,when

thereisMORElightavailableforphotosynthesis andpeaksoccurduringthewinter,when

thereisLESSlightavailableforphotosynthesis.



EXAMPLESFROMLAB5

ElodeaandCO2

Inourfirsttesttube,weaddedphenolredtowater.

Inthesecondandthirdtubes,weaddedphenolredtowaterandCO2viaourown

respiration.

WethenaddedtheElodeatothesecondtube.

Throughphotosynthesis,theElodeaabsorbedtheCO2presentinthewater+phenolredsolution.

Therefore,thefirsttesttube(NoCO2present)isourpositivecontrol,whilethethirdtesttube(CO2present)isournegativecontrol.

YeastandGlucose

Inthefirsttube,wehadonlyyeastandwater.

Inthesecondtube,wehadyeast,water,andglucose.

Inthethirdtube,wehadyeast,NaN3(sodiumazide)andglucose.

Weaddedphenolredtoallthreetubes.

Wesawthemostdrasticchangeinthesecondtube,whichwasevidencebythepresenceof

CO2bubblesandcolorchange.

Wesawminimalchangeinthethirdtube,becauseNaN3inhibitedaerobicrespiration.

Wesawnochangeinthefirsttubebecausetherewasnoglucose(and,therefore,nonutrients)fortheyeasttobreakdown.



CRITICALTHINKING

KEYTERMS

- Biomass

- Photosynthesis

- CellularRespiration- ATP

- AnaerobicRespiration

- Glycolysis

- Fermentation- AerobicRespiration

- KrebsCycle

- ETS

- GreenhouseGas- GreenhouseEffect

- GlobalWarming

- ClimateChange

- KeelingCurve

QUESTIONS

1.Howisphotosynthesisdifferentfromrespiration?2.Whatdolacticacidandalcoholrepresent?

3.Describeanaerobiccellularrespiration.4.Describeaerobiccellularrespiration.

5.Howarephotosynthesisandrespirationrelated?

6.DescribethedifferencesbetweenthepositiveandnegativecontrolinourInvestigation

withElodea.

7.Whatpurposedidglucoseservefortheyeast?

8.Whatdidphenolreddetectinallthreeinvestigationsofthislab?

9.Howdogreenhousegasesgettheirname?

10.Howisthegreenhouseeffectbeneficial?

11.Whichgreenhousegasdohumanshavethemostcontrolover?

12.Whyshouldn’twecontinuetodestroyforests(kelpandrainforestalike)?

13.DrawtheKeelingcurveandlabelthex-axis,y-axis,describewhatthegraphtellsyouandexplainwhatthefluctuationsmean.

14.DoesdeforestationaddorreducetheamountofCO2intheatmosphere?Why?

FROMTHELAB

YeastinFermentationTubes

Explainwhathappenedwhenglucosewaspresentwithyeast.Howwasthisdifferentfrom

whenglycerol(lipid)orproteinwaspresentwithyeast?Whydidtheglycerolandprotein

havedifferentreactionsfromtheglucose?

bio 100l – lab 5 – photosynthesisrespiration(4)

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