AP Bio Ch7 Power Point2229

8/3/2019 AP Bio Ch7 Power Point2229

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ChapterChapter 7

PhotosynthesisPhotosynthesis


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Chapter 72

What Is Photosynthesis?What Is Photosynthesis?

Early cells evolved the abilityEarly cells evolved the abilityto perform photosynthesisto perform photosynthesisabout 2 billion years agoabout 2 billion years ago

PhotosynthesisPhotosynthesis is the ability tois the ability tocapture sunlight energy andcapture sunlight energy andconvert it to chemical energyconvert it to chemical energy

Most forms of life on EarthMost forms of life on Earthdepend on the chemicaldepend on the chemicalenergy produced byenergy produced by

photosynthetic organismsphotosynthetic organisms


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Chapter 73

The PhotosyntheticThe PhotosyntheticEquationEquation

6CO2

carbon

dioxide

+ 6H2O

water

+ light energysunlight

C6H12O6glucose

(sugar)

+ 6O2oxygen

Photosynthesis occurs in plants,Photosynthesis occurs in plants,algae, andalgae, and some prokaryotessome prokaryotes

Photosynthetic organisms arePhotosynthetic organisms areautotrophsautotrophs (self-(self- feeders)feeders)Photosynthesis in plants occursPhotosynthesis in plants occurswithinwithin chloroplastschloroplasts


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Chapter 74

Gases, Sugar, andGases, Sugar, andWater CycleWater CycleProduction of carbonProduction of carbon

compounds like glucosecompounds like glucose

(photosynthesis) is linked(photosynthesis) is linkedwith energy extraction (inwith energy extraction (incellular respiration)cellular respiration)

Water, COWater, CO22, sugar, and O, sugar, and O22

cycle between the twocycle between the twoprocessesprocesses

Photosynthesis and cellularPhotosynthesis and cellular


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Chapter 75

Photosynthesis &Photosynthesis &RespirationRespiration


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Chapter 76

Adaptations forAdaptations forPhotosynthesisPhotosynthesis

LeavesLeaves

ChloroplastsChloroplasts


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Chapter 77

Structures ofStructures ofPhotosynthesisPhotosynthesis


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Chapter 78

LeavesLeavesFlattened leaf shapeFlattened leaf shape

exposes large surface areaexposes large surface areato catch sunlightto catch sunlight

Upper and lower leafUpper and lower leaf

surfaces of a leaf comprisesurfaces of a leaf comprisethethe epidermisepidermis

Waxy, waterproofWaxy, waterproofcuticlecuticle onon

outer surfaces reducesouter surfaces reduceswater evaporationwater evaporation


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Chapter 79

Leaf AnatomyLeaf AnatomyAdjustable pores calledAdjustable pores calledstomatastomata allow for entry ofallow for entry ofair with COair with CO22

InnerInner mesophyllmesophyll cell layerscell layerscontain majority ofcontain majority ofchloroplastschloroplasts

Vascular bundlesVascular bundles (veins)(veins)supply water and mineralssupply water and mineralsto the leaf while carryingto the leaf while carrying

sugars away from the leafsugars away from the leaf


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Chapter 710

Internal Leaf StructureInternal Leaf Structure

Internal leaf structure isInternal leaf structure is

crucial to photosynthesiscrucial to photosynthesissince photosynthesissince photosynthesisoccurs primarily in theoccurs primarily in the

leaves of land plansleaves of land plans


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Chapter 711

Leaf StructureLeaf Structure

MesophylMesophylCellCell

MesophylMesophylCellCell

Upper EpidermisUpper EpidermisUpper EpidermisUpper Epidermis

LoweLowe

EpidermiEpidermi

LoweLowe

EpidermiEpidermiVeinVeinVeinVein StomaStomaStomaStoma


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Chapter 712

Anatomy of a ChloroplasAnatomy of a Chloroplas

Mesophyll cells have 40-Mesophyll cells have 40-

200 chloroplasts each200 chloroplasts eachChloroplasts are boundedChloroplasts are boundedby a double membraneby a double membrane

composed of thecomposed of the innerinner andandouter membranesouter membranes


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Chapter 713

Anatomy of a ChloroplastAnatomy of a Chloroplast

TheThe stromastroma is the semi-fluidis the semi-fluidmedium within the innermedium within the innermembranemembrane

Disk-shaped sacs calledDisk-shaped sacs calledthylakoidsthylakoids found within thefound within thestroma in stacks calledstroma in stacks calledgranagrana


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Chapter 714

Chloroplast StructureChloroplast Structure

Inner & OuterInner & Outer

MembranesMembranes

ThylakoidsThylakoids

GranumGranum

StromaStroma(space)(space)

Th E i Vi iblTh E i Vi ibl


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Chapter 715

The Energy in VisibleThe Energy in VisibleLightLightThe sun radiatesThe sun radiates

electromagnetic energyelectromagnetic energyVisible light is radiationVisible light is radiationfalling between 400-750falling between 400-750

nanometers of wavelengthnanometers of wavelengthPackets of energy calledPackets of energy calledphotonsphotons with different energywith different energy

levelslevelsShort-wavelength photonsShort-wavelength photonsare very energeticare very energetic

Lon er-wavelen th hotonsLon er-wavelen th hotons

16


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Chapter 716

Light, ChloroplastLight, ChloroplastPigments, & PhotosynthesisPigments, & Photosynthesis

Gamma RaysGamma Rays X-RaysX-RaysUVUV InfraredInfraredMicro-Micro-waveswaves RadioRadioWavesWaves

Visible LightVisible Light

400400 450450 500500 550550 600600 650650 700700 7575

Wavelength (nanometers, nm)Wavelength (nanometers, nm)

17Li ht C t d bLi ht C t d b


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Chapter 717

Light Captured byLight Captured byPigmentsPigments

Action of light-capturingAction of light-capturingpigmentspigmentsAbsorptionAbsorption of certainof certain

wavelengths (light iswavelengths (light istrapped)trapped)ReflectionReflection of certainof certain

wavelengths (lightwavelengths (lightbounces back)bounces back)TransmissionTransmission of certainof certain

wavelengths (lightwavelengths (light

18Li ht C t d bLi ht C t d b


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Chapter 718

Light Captured byLight Captured byPigmentsPigments

Absorbed light drivesAbsorbed light drivesbiological processes whenbiological processes whenit is converted to chemicalit is converted to chemicalenergyenergy

Common pigments found inCommon pigments found inchloroplasts include:chloroplasts include:ChlorophyllChlorophyllaaandandbbAccessory pigments suchAccessory pigments such

asas carotenoidscarotenoids

h 19


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Chapter 719Light Captured byLight Captured by

PigmentsPigmentsChlorophyll a and bChlorophyll a and b absorbabsorb

violet, blue, and red lightviolet, blue, and red lightbut reflect green lightbut reflect green light(hence they appear green)(hence they appear green)

CarotenoidsCarotenoids absorb blue andabsorb blue andgreen light but reflectgreen light but reflectyellow, orange, or redyellow, orange, or red

(hence they appear yellow-(hence they appear yellow-orange)orange)

Pigment absorbs visiblePigment absorbs visible

lightlight

Ch 720

Absorption SpectraA sorpt on Spectra


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Chapter 720

00

2020

4040

6060

8080

100100

%L

ight

Absorption

%L

ight

Absorption

0000 450450 500500 550550 600600 650650 700700 750750

Wavelength (nanometers)Wavelength (nanometers)

0000 450450 500500 550550 600600 650650 700700 750750

Absorption SpectraA sorpt on Spectra

Visible LightVisible Light

ChlorophyllChlorophyll

CarotenoidsCarotenoids

PhycocyaPhycocyaninnin

CollectivCollectivelyely

Chapter7 7Light, ChloroplastLight, ChloroplastPigments &PhotosynthesisPigments &Photosynthesis

GammaRaysGammaRays XX--RaysRaysUVUV InfraredInfraredMicroMicro--waveswavesRadioRadioWavesWaves

VisibleLightVisibleLight

777777 777777 777777 777777 777777 777777 777777 777777

Wavelength(nanometers)Wavelength(nanometers)

Ch t 721O i f


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Chapter 721

GlucoseGlucose

OO22

Overview ofOverview ofPhotosynthesisPhotosynthesis

Light-DependentLight-DependentReactionsReactions

(in thylakoids)(in thylakoids)

Light-IndependentLight-IndependentReactionsReactions

(in stroma)(in stroma)

DepleteDepletedd

CarriersCarriers(ADP,(ADP,

NADPNADP++))

DepleteDepletedd

CarriersCarriers

(ADP,(ADP,

NADPNADP++))

EnergizEnergizeded

CarriersCarriers

(ATP,(ATP,

NADPH)NADPH)

HH22OO

CC

OO22

Ch t 722

The PhotosystemsThe Photosystems


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Chapter 722

The PhotosystemsThe Photosystems

Ch t 723Li ht DependentLight Dependent


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Chapter 723

Light-DependentLight-DependentReactionsReactions

Steps of the light reactions:Steps of the light reactions:

Accessory pigments inAccessory pigments in

Photosystems absorbPhotosystems absorblight and pass energy tolight and pass energy toreaction centersreaction centers containingcontaining

chlorophyllchlorophyllReaction centers receiveReaction centers receive

energized electronsenergized electrons

Ch t 724Light DependentLight Dependent


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Chapter 724

Light-DependentLight-DependentReactionsReactionsEnergized electrons thenEnergized electrons then

passed down a series ofpassed down a series ofelectron carrierelectron carriermolecules (molecules (ElectronElectron

Transport ChainTransport Chain))Energy released fromEnergy released from

passed electrons used topassed electrons used to

synthesizesynthesize ATPATP from ADPfrom ADPand phosphateand phosphate

Energized electrons alsoEnergized electrons also

used to makeused to make NADPHNADPH fromfrom

Ch t 725


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Chapter 725

Thylakoid Structure &Thylakoid Structure &Light-Dependent ReactionsLight-Dependent Reactions

Ch t 726


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Chapter 726

Oxygen as a By-productOxygen as a By-product

Chapter 727

ChemiosmosiChemiosmosi


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Chapter 727

ChemiosmosiChemiosmosis 1s 1

Chapter 728


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Chapter 728

ChemiosmosChemiosmosis 2is 2

Chapter 729LightLight InIndependentdependent


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Chapter 729

Light-Light-InIndependentdependentReactionsReactions

NADPH and ATP from light-NADPH and ATP from light-dependent reactions useddependent reactions usedto power glucose synthesisto power glucose synthesis

Light notLight not directlydirectlynecessarynecessaryfor light-independentfor light-independentreactions if ATP & NADPHreactions if ATP & NADPH

availableavailableLight-independent reactionsLight-independent reactionscalled thecalled the Calvin-BensonCalvin-Benson

CycleCycle oror CC33 CycleCycle

Chapter 730


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Chapter 730The CThe C33 CycleCycle

6 CO6 CO22 used to synthesize 1used to synthesize 1glucose (Cglucose (C66HH1212OO66))

Carbon dioxide is capturedCarbon dioxide is captured

and linked to ribuloseand linked to ribulosebisphosphate (RuBP)bisphosphate (RuBP)

ATP and NADPH from lightATP and NADPH from light

dependent reactions useddependent reactions usedto power Cto power C33 reactionsreactions

Chapter 731


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Chapter 731CC33 Cycle Has Three PartsCycle Has Three Parts

1. Carbon fixation (carbon1. Carbon fixation (carboncapture)capture)

6 Ribulose bisphosphate6 Ribulose bisphosphate(RuBP) molecules combine(RuBP) molecules combinewith 6COwith 6CO22

Fixation step andFixation step andsubsequent reactions yieldsubsequent reactions yield

twelve 3-carbontwelve 3-carbonphosphoglyceric acid (PGA)phosphoglyceric acid (PGA)moleculesmolecules

Chapter 732


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2. Synthesis of2. Synthesis ofGlyceraldehyde 3-Glyceraldehyde 3-Phosphate (G3P)Phosphate (G3P)

Energy is donated by ATPEnergy is donated by ATPand NADPHand NADPH

Phosphoglyceric acid (PGA)Phosphoglyceric acid (PGA)molecules are convertedmolecules are converted

into glyceraldehyde 3-into glyceraldehyde 3-Phophate (G3P) moleculesPhophate (G3P) molecules

Chapter 733


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3. Regeneration of3. Regeneration ofRibulose bis-phosphateRibulose bis-phosphate(RuBP)(RuBP)

10 of 12 G3P molecules10 of 12 G3P moleculesconverted into 6 RuBPconverted into 6 RuBPmoleculesmolecules

2 of 12 G3P molecules used2 of 12 G3P molecules usedto synthesize 1 glucoseto synthesize 1 glucose ATP energy used for theseATP energy used for these

reactionsreactions

Chapter 734


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Chapter 734The CThe C33

Cycle ofCycle of

CarbonCarbonFixationFixationoror

DarkDarkReactionsReactionsororLight-Light-

IndependeIndependentntReactionsReactions

oror

Chapter 735Relationship BetweenRelationship Between


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Chapter 735

Relationship BetweenRelationship BetweenReactionsReactions

The photo part ofThe photo part ofphotosynthesis refers tophotosynthesis refers to

the capture of light energythe capture of light energy(light dependent(light dependentreactions)reactions)

The synthesis part ofThe synthesis part ofphotosynthesis refers tophotosynthesis refers toglucose synthesis (light-glucose synthesis (light-

inindependent reactions)dependent reactions)

Chapter 736Relationship BetweenRelationship Between


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Chapter 736

Relationship BetweenRelationship BetweenReactionsReactions

Light dependent reactionsLight dependent reactionsproduce ATP and NADPHproduce ATP and NADPH

which is used to drivewhich is used to drivelight-independentlight-independentreactionsreactions

Depleted carriers (ADP andDepleted carriers (ADP andNADPNADP++) return to light-) return to light-dependent reactions fordependent reactions for

rechargingrecharging

Chapter 737A Summary ofA Summary of


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Chapter 737

A Summary ofA Summary ofPhotosynthesisPhotosynthesis

Light-Light-

dependentdependentreactionsreactionsoccur inoccur in

thylakoidsthylakoids

Light-Light-independeindependentnt

reactionsreactions(c(c33 cycle)cycle)

occur inoccur instromastroma

Chapter 738atera er 22 an t ean e 44


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Chapter 738

ater,a er, 22, an t e, an e 44PathwayPathwayThe ideal leaf:The ideal leaf:

has large surface area tohas large surface area tointercept sunlightintercept sunlight

are porous to allow for COare porous to allow for CO22

entry from airentry from airProblem: Substantial leafProblem: Substantial leafporosity leads to substantialporosity leads to substantial

water evaporation, causingwater evaporation, causingdehydration stress on the plantdehydration stress on the plant

Plants evolved waterproofPlants evolved waterproofcoating and adjustable porescoating and adjustable pores(stomata) for CO(stomata) for CO2 entrentry

Chapter 739


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Chapter 739

When Stomata Are CloseWhen Stomata Are CloseWhen stomata close, COWhen stomata close, CO22 levelslevels

drop and Odrop and O22 levels riselevels riseCarbon fixing enzyme combines OCarbon fixing enzyme combines O22instead of COinstead of CO22 with RuBP (calledwith RuBP (called

photorespirationphotorespiration))Photorespiration:Photorespiration:OO22 is used up as COis used up as CO22 isisgeneratedgenerated

No useful cellular energy madeNo useful cellular energy madeNo glucose producedNo glucose producedPhotorespiration isPhotorespiration isun roductive and wastefulunproductive and wasteful

Chapter 740


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Chapter 740

When Stomata Are ClosedWhen Stomata Are Closed

Hot, dry weather causesHot, dry weather causesstomata to stay closedstomata to stay closed

Oxygen levels rise as carbonOxygen levels rise as carbondioxide levels fall inside leafdioxide levels fall inside leaf

Photorespiration veryPhotorespiration very

common under suchcommon under suchconditionsconditions

Plants may die from lack ofPlants may die from lack of

glucose synthesisglucose synthesis Chapter 74144 ants e ucean s e uce


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Chapter 741

44 ants e ucean s e ucePhotorespirationPhotorespiration

CC44 plants have chloroplastsplants have chloroplasts

in bundle sheath cells as wellin bundle sheath cells as well

as mesophyll cellsas mesophyll cellsBundle sheath cellsBundle sheath cellssurround vascular bundlessurround vascular bundles

deep within mesophylldeep within mesophyllCC33 plants lack bundleplants lack bundle

sheath cell chloroplastssheath cell chloroplasts

Chapter 742


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Chapter 742CC33 Plants & the PathwayPlants & the Pathway

CC33

plants useplants usethe Cthe C33 pathwaypathway

In a CIn a C33 plant,plant,mostmost

chloroplasts arechloroplasts are

in mesophyllin mesophyll

Chapter 743


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Chapter 743CC33 Plants & the PathwayPlants & the Pathway

MuchMuchphotorespiratiophotorespiration occurs undern occurs under

hot, dryhot, dryconditionsconditions

Chapter 744CC44 Plants & the CPlants & the C44


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Chapter 744

CC44 Plants & the CPlants & the C44PathwayPathway

CC44

plants useplants usethe Cthe C44 pathwaypathway

In a CIn a C44 plant,plant,both mesophyllboth mesophyll& bundle-sheath& bundle-sheath

cells containcells contain

Chapter 745COCO ii

Mesophyll cell in a CMesophyll cell in a C44 plantplant


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Chapter 745

CC44 PlantsPlants& the C& the C44PathwayPathway

Almost noAlmost nophotorespiratiphotorespirati

on occurson occursunder hot, dryunder hot, dry

conditions.conditions.

COCO22 isiscapturedcaptured

with a highlywith a highly

specificspecificenzyme.enzyme.

MuchMuchglucoseglucose

synthesissynthesis

occurs.occurs.

p yp y pp

Bundle-sheath cell in a CBundle-sheath cell in a C44

Ch tCh t 7


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ChapterChapter 7

The endThe end

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AP Bio Ch7 Power Point2229