Chapter 35

APBiologyReadingGuideChapter35:PlantStructure,Growth,andDevelopment

Name____JyothisJames__________Period____1_____ Chapter35:PlantStructure,Growth,andDevelopment Concept35.1Theplantbodyhasahierarchyoforgans,tissues,andcells 1.

Thisconceptisorganizedintothreesections—plantorgans,tissues,andcells.Beginby definingatissueandanorgan.

Atissueisagroupofcellswithacommonfunction,structureorboth.Anorganconsistsofseveral typesoftissuesthattogethercarryoutparticularfunctions. 2. 3.

Thethreeplantorgansare___roots____,___stems___,and__leaves__. OnFigure35.2,labeltheshootsystem,rootsystem,apicalbud,axillarybud,androotsystem.

4.

Definerootandthenexplainthedifferencebetweenataprootandlateralroots.

Root-Arootisamulticellularorganthatanchorsavascularplantinthesoil,absorbsmineralsand water,andoftenstorescarbohydrates. TaprootandLateralroot-Mosteudicotsandgymnospermshavea taprootsys-tem, consistingofone mainverticalroot,thetaproot,thatdevelopsfromanembryonicroot.Thetaprootgivesriseto lateralroots,alsocalledbranchroots. 5.

Thisphotographshowsthe roothairsofaradish.Whatisthefunctionof roothairs?

Althoughtheentirerootsystemhelpsanchoraplant,inmostplantstheabsorptionofwaterand mineralsoccursprimarilynearthetipsofroots,wherevastnumbersoftinyroothairsin-creasethe surfaceareaoftherootenormously

6.

Whatistheadvantageof apicaldominance toaplant?

Byconcentratingresourcesonelongation,theevolutionaryadaptationofapicaldominanceincreases theplant'sexposuretolight. 7. 8.

Themainfunctionofaleafis__toperformphotosynthesis__. Whatarefiveadditionalfunctionsthatmodifiedleavescanperform? a. Tendrils-Thetendrilsprovidesupportbyclingingontootherobjects b. Spinesprovideprotectionfortheplant c. Storageleavesspecializeinstoringwater d. Reproductiveleavesproduceplantletswhichfalloffandreproduce e. Bracts-theirbrightcolorsattractpollinators

9.

Plantshavethreetypesoftissues.Placethenameofeachtissuetypeanditsfunctioninthe tablebelow. a.

dermaltissuesystem-istheplant'souterprotectivecovering.Inadditionto protectingtheplantfromwaterlossanddisease,theepidermishasspecialized characteristicsineachorgan.Theycanalsoprovidedefenseagainstin-sectsby formingabarrierorbysecretingstickyfluidsandtoxiccompounds

b.

vasculartissuesystem-carriesoutlong-distancetrans-portofmaterialsbetween therootandshootsystems.Theh·...otypesofvasculartissuesarexylemand phloem.

c.

groundtissuesystem-Groundtissuethatisinternaltothevas-culartissueis knownaspith,andgroundtissuethatisexternaltothevasculartissueiscalled cortex.Thegroundtissuesystemisnotjustfiller.Itincludesvariouscells specializedforfunctionssuchasstorage,photosynthesis,andsupport.

10. Whatisthefunctionofthe cuticle?  awaxycoatingontheepidermalsurface,helpspreventwaterloss. 11. Xylemconducts__wateranddissolvedmineralsupwardfromrootsintotheshoots__. 12. Xylemtransporttendstobeinonedirection,butphloemtransportismorecomplicated. Explainthepatternofsugarflowinphloemtissue. Phloemtransportssugars,theproductsofphotosynthesis,fromwheretheyaremade(usually theleaves)towheretheyareneeded-usuallyrootsandsitesofgrowth,suchasdevelopingleaves andfruits.

13. Thetwomajortissuesofthegroundtissuesystemarepithandcortex.Wherearetheyfound intheplant? Tissuesthatareneitherdermalnorvasculararepartofthegroundtissuesystem.Theyarefound betweenthedermalandvasculartissue. 14. a a.

Parenchymacells-performmostofthemetabolicfunctionsoftheplant, synthesizingandstoringvariousorganicproducts.Mostparenchymacellsretainthe

b.

c.

d.

e.

abilitytodivideanddifferentiateintoothertypesofplantcellsunderparticular conditions-duringwoundrepair,forexample. Collenchymacells-Groupedinstrandsorcylinders,collenchymacellshelpsupport youngpartsoftheplantshoot.Atmaturity,collenchymacellsarelivingandflexible, elongatingwiththestemsandleavestheysupport Sclerynchymacells-Alsofunctioningassupportingelementsintheplant,butwith thicksecondarywallsthatareusuallystrengthenedbylignin,sclerenchymacellsare muchmorerigidthancollenchymacells.Maturesclerenchymacellscannotelongate, andtheyoccurinregionsoftheplantthathavestoppedgrowinginlength. Sclerenchymacellsaresospecializedforsupportthatmanyaredeadatfunctional maturity,buttheyproducesecondarywallsbeforetheprotoplast(thelivingpartof thecell)dies. Xylemcells-Tracheidsarelong.thincellswithtaperedends.Watermovesfromcell tocellmainlythroughthepits,whereitdoesnottocrossthicksecondarywalls. Vesselelementsaregenerallywider,shorter,thinnerwalled,andlesstaperedthan thetracheids.Theyarealignedendtoend,forminglongmicropipesknownas vessels.

i. Phloem-Unlikethewater-conductingcellsofthexylem,thesugar-conductingcells ofthephloemarealiveatfunctionalmaturity.Inseedlessvascularplantsand gymnospenns,sugarsandotherorganicnutrientsaretransportedthroughlong, narrowcellsGilledsievecells.Inthephloemofangiosperms,thesenutrientsare transportedthroughsievetubes,whichconsistofchainsofcellscalledsievetubeor sievetubemembers.

i. 15. Compareandcontrastthefollowingstructures: a. Tracheidsarelong.thincellswithtaperedends.Watermovesfromcelltocell mainlythroughthepits,whereitdoesnottocrossthicksecondarywalls.Vessel elementsaregenerallywider,shorter,thinnerwalled,andlesstaperedthanthe tracheids. b. Theendwallsbetweensieve-tubeelements,calledsieveplates,hawporesthat facilitatetheflowoffluidfromcelltocellalongthesievetube.Alongsideeachsievetubeelementisanonconductingcellcalledacompanionwhichisconnectedtothe sieve-tubeelementbynumerouschannels,plasmodesmata 16. summarycharts. a. Thethreeplantorgansare:roots,stems,andleaves b. Thethreebasicplanttissuesare:dermal,vascular,ground c. Thethreebasicplantcellsare:Parenchyma,Collenchyma,Sclerynchyma,xylemand phloem 17. Whatisthedifferencebetweenindeterminategrowthanddeterminategrowth? Amajordifferencebetweenplantsandmostanimalsisthatplantgrowthisnotlimitedtoan embryonicorjuvenileperiod.Instead,growthoccursthroughouttheplant'slife,aprocessknownas indeterminategrowth.Atanygiventime,atypicalplantconsistsofembryonic,developing,and matureorgans.Exceptfordormantperiods,mostplantsgrowcontinuously.Incontrast,most animalsandsomeplantorgans-suchasmostleaves,thorns,andflowers-undergodeterminate growth;thatis,theystopgrowingafterreachingacertainsize. 18. Althoughplantsgenerallyshowindeterminategrowth,whatarethreeexamplesofplant partsthatshowdeterminategrowth? Leaves,thorns,andflowers 19. Basedonthelengthoftheirlifecycle,plantsarecategorizedintothreegroups.Explainwhat eachcategorymeansbelow,andprovideanexample. a. Annualscompletetheirlifecycle-fromgerminationtoflower·ingtoseedproduction todeath-inasingleyearorless.Manywildflowersareannuals,asaremoststaple foodcrops,includinglegumesandcerealgrainssuchaswheatandrice. b. Biennialsgenerallyrequiretwogrowingseasonstocompletetheirlifecycle, floweringandfruitingonlyintheirsecondyear.Radishesandcarrotsarebiennials, thoughtheyareusuallyharvestedafterthefirstyear.

c.

Perennialslivemanyyearsandincludetrees,shrubs,andsomegrasses.Some buffalograssoftheNorthAmericanplainsisthoughttohavebeengrowingfor 10,000yearsfromseedsthatsproutedatthecloseofthelasticeage. 20. Plantsarecapableofindeterminategrowthbecausetheyhaveperpetuallyembryonictissues calledmeristems. 21. Explainthefollowingrelationships: a. Apicalmeristemsandprimarygrowth:Apicalmeristems,locatedatthetipsofroots andshootsandintheaxillarybudsoffshoots,provideadditionalcellsthatenable theplanttogrowinlength,aprocessknownasprimarygrowth.Primarygrowth allowsrootstoextendthroughoutthesoilandshootstoincreasetheirexposureto light.Inherbaceous(nonwoody)plants,primarygrowthproducesall,oralmostall oftheplantbody. b. Lateralmeristemsandsecondarygrowth:Woodyplants.however,alsogrowin girthinthepartsofstemsandrootsthatnolongergrowinlength.Thisgrowthin thickness,knownassecondarygrowth,iscausedbytheactivityoflateralmeristems calledthevascularcambiumandcorkcambium. c. Primarygrowthandsecondarygrowth:Primarygrowthallowsrootstoextend throughoutthesoilandshootstoincreasetheirexposuretolight.Inherbaceous (nonwoody)plants,primarygrowthproducesall,oralmostall.oftheplantbody. Woodyplants.however,alsogrowingirthinthepartsofstemsandrootsthatno longergrowinlength.Thisgrowthinthickness,knownassecondarygrowth. 22. Thefigurebelowshowsanimagethatislikeaslidemanystudentsstudyinamitosislaband islabeledforthislessonasthe“Primarygrowthofaroot.”Labeltheninestructuresshown inthefigure:cortex,vascularcylinder,epidermis,apicalmeristem,rootcap,roothair,zone ofdifferentiation,zoneofelongation,andzoneofcelldivision.

23. Explainwhateventsoccurinthezoneofcelldivision,zoneofelongation,andzoneof differentiation. Thethreezonesgradetogether,withnosharpboundaries.Thezoneofcelldivisionincludestheroot apicalmeristemanditsderivatives.Newrootcellsareproducedinthisregion,includingtherootcap. Typically,aboutamillimeterbehindthetipoftherootisthezoneofelongation,whererootcells

elongate,sometimestomorethantentimestheiroriginallength.Cellelongationinthiszonepushes thetipfartherintothesoil.Meanwhile,therootapicalmeristemkeepsaddingcellstotheyounger endofthezoneofelongation.Evenbeforetherootcellsfinishlengthening,manybeginspecializing instructureandfunction.Inthezoneofdifferentiation,orzoneofmaturation,cellscompletetheir differentiationandbecomedistinctcelltypes. 24. Inmostroots,thexylemandphloemisasolidcylinderofvasculartissuelocatedinthe centeroftherootandcalledthestele.Thefigurebelowshowsthesteleofadicotroot.Label thexylem,phloem,endodermis,andpericycle.Alsodefinethetwonewtermsasindicated.

Endodermis:Theinnermostlayerofthecortexiscalledtheendodermis,acylinderonecellthickthat formstheboundarywiththevascularcylinder. Pericycle:Lateralrootsarisefromthepcricyclc,theoutermostcelllayerinthevascularcylinder, whichisadjacenttoandjustinsidetheendodermis. 25. Whymustnewrootsformedbythepericycleoriginateinthecenteroftheroot? Alateralrootcannotoriginateneartheroot'ssurfacebecauseitsvascularsystemmustbe continuouswiththevascularcylinderatthecenteroftheestablishedroot. 26. FromFigure35.16,labelshootapicalmeristem,leafprimordia,youngleaf,developing vascularstrand,andaxillarybudmeristems.

27. Whatstructureinthisfigureisresponsibleforprimarygrowth? Apicalmeristem 28. Itispossibletotellayoungeudicotfromamonocotbythestructureofthestem.Inthe followingfigure,labeltheeudicot,monocot,epidermis,andvascularbundles.

29. Howisthearrangementofvascularbundlesdifferentinmonocotanddicotstems? Inmosteudicotspecies,thevasculartissueconsistsofvascularbundlesarrangedinaring.Thexylem

ineachvascularbundleisadjacenttothepith,andthephloemineachbundleisadjacenttothe cortex.Inmostmonocotstems,thevascularbundlesarescatteredthroughoutthegroundtissue, ratherthanformingaring. 30. Tounderstandtheprocessofphotosynthesis,studentsareexpectedtoknowleafstructure ingreaterdetail.UsingFigure35.18,labeleachstructurejustasshowninthetext.

31. 32. 33. 34.

Whatgascriticaltophotosynthesisenterstheleafthroughstoma?CO2 Whatislostthroughthestomathatleadstotranspiration?Water IsthisaC3,C4,orCAMleaf?C4 Primarygrowtharisesfromapicalmeristemsandresultsin___growth___ofroots,stems,and leaves.Secondarygrowtharisesfrom_____________and___vascular_____cambiumandresults inincreased___girth___ofrootsandstems. 35. Explainwhatisproducedbythesestructures a. Vascularcambium:Thevascularcambiumisacylinderofmeristematiccells,of-ten onlyonecellthick.Itincreasesincircumferenceandalsoaddslayersofsecondary xylemtoitsinteriorandsecondaryphloemtoitsexterior. b. CorkCambium:Duringtheearlystagesofsecondarygrowth,theepidermisis pushedoutward,causingittosplit,dry,andfalloffthestemorroot.Itisreplacedby twotissuesproducedbythefirstcorkcambium,acylinderofdividingcellsthat arisesintheoutercortexofstemsandintheouterlayerofthepericycleinroots. 36. ReadthetextthataccompaniesFigure35.19andthenanswerthesequestions. a.Whatresultsinprimarygrowthofthestem? Thestemthickensasthevascularcambiumformssecondarytotheinsideandsecondaryphloemto theoutside. b.Whatcellsareformedtotheinsideandtheoutsideofthevascularcambium?

Asthevascularcambium'sdiameterincreases.Thesecondaryphloemandothertissuesto thecambiumcan'tkeeppacebecausetheircellsnolongerdivide,Asaresult,thesetissues, includingtheepidermis,willeventuallyrupture.Asecondlateralmeristem,thecork cambium,developsfromparenchymacellsinthecortex.Thecorkcambiumproducescork cells,whichreplacetheepidermis. c.Whatisthedifferenceintheformationofprimaryxylemandphloemversussecondary xylemandphloem? Primaryxylemisthexylemthatisformedduringprimarygrowthfromprocambium.It includesprotoxylemandmetaxylem.Metaxylemdevelopsaftertheprotoxylembutbefore secondaryxylem.Itisdistinguishedbywidervesselsandtracheids.Asitdevelops,thexylem canbecomeendarchorexarch. Secondaryxylemisthexylemthatisformedduringsecondarygrowthfromvascular cambium.Althoughsecondaryxylemisalsofoundinmembersofthe"gymnosperm"groups GnetophytaandGinkgophytaandtoalesserextentinmembersoftheCycadophyta 37. Whatvasculartissueformsthebark,andwhatisthefunctionofthebark? Manypeoplethinkthatbarkisonlytheprotectiveoutercoveringofawoodystemorroot.Actually, barkincludesalltissuesexternaltothevascularcambium.Inanoutwarddirection,itsmain componentsarethesecondaryphloem(producedbythevascularcambium),themostrecent periderm,andalltheolderlayersofperiderm 38. Whattissuesareincludedinthebarkofatree? SecondaryPhloemandlayersofperiderm 39. Onthisfigure,addtheselabels:corkcambium,cork,periderm,bark,growthring,secondary xylem,secondaryphloem,andvascularcambium.

40. LookbackatthesteminFigure35.19andfindthehorizontalslitsinthebark,knownas lenticels.Youmayhavenoticedlenticelsontheyoungtwigsoftreesorshrubs.Whatisthe functionoflenticels? Dottingtheperidemaresmall,raisedareascalledlenticels,inwhichthereismorespacebetween corkcells,enablinglivingcellswithinawoodystemorroottoexchangegaseswiththeoutsideair. Lenticelsoftenappearasslits.