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Homework#2Tutorials46Due:11:00pmonSunday,May31,2015

Youwillreceivenocreditforitemsyoucompleteaftertheassignmentisdue.GradingPolicy

Activity:TheTreeofLife

Clickheretoviewthisanimation.

Thenanswerthequestions.

PartA

WhichgroupwasnotdescribedinWoese'streeoflifeanalysis?

Hint1.

WhichgroupisnotoneofthethreemajordivisionsoflifeformsdeterminedbyWoese?

ANSWER:

CorrectProkaryawasnotoneofthegroupsdescribedinWoese'streeoflifeanalysis.

PartB

WhatcharacteristicswereusedtoclassifyorganismsbeforeWoese'streeoflifeanalysis?

Hint1.

Whatcharacteristicscanscientistsusetodivideorganismsintogroups?

ANSWER:

Correct

Beforethetreeoflifeanalysis,organismswereclassifiedasprokaryotesiftheylackedamembraneboundnucleusoreukaryotesiftheypossessedamembraneboundnucleus.

EukaryaBacteriaProkaryaArchaea

NumberofcellsintheorganismDifferencesinribosomalRNAsequencesPresenceofamembraneboundnucleusCompositionofthecellwall

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PartC

Trueorfalse?DatashowingthattheBacteriawerethefirstlineagetodivergefromthecommonancestorofalllivingorganismssuggestthattheArchaeaandEukaryaaremorecloselyrelatedtoeachotherthantheyaretotheBacteria.

Hint1.

Howisthetreeoflifeorganized?

ANSWER:

Correct

PartD

Whichofthefollowingstatementsaboutphylogenetictreesistrue?

Hint1.

Thinkaboutthedifferencebetweenmonophyleticandparaphyleticgroups.

ANSWER:

Correct

Thisstatementistruethecommoncharacteristicsofaparaphyleticgroupmayhavearisenfromlateralgenetransfertosome,butnotall,lineages.

PartE

WhichmoleculedidCarlWoesestudytoproducehistreeoflife?

Hint1.

Thismoleculeevolvesveryslowlybecauseitiscriticaltothefunctionofacellularstructurethatispresentinalldomainsofthetreeoflife.

ANSWER:

Correct

RibosomalRNAwasthemoleculeusedtoproduceWoese'sphylogenybecauseitevolvesslowlyandiscriticaltothefunctionoftheribosome,whichservesthesamefunctioninallthreedomainsinthetreeoflife.

PartF

TrueFalse

Amonophyleticgroupconsistsofacommonancestorandsomeofitsdescendants.Aparaphyleticgrouphasnotexperiencedlateralgenetransfer.Aparaphyleticgroupconsistsofacommonancestorandsomeofitsdescendants.Aparaphyleticgroupconsistsofanancestralpopulationandallofitsdescendants.

MessengerRNADNARibosomalRNARibosome

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Whatislateralgenetransfer?

Hint1.

Considerhowgeneticinformationcanmoveamongdistantlyrelatedlineages.

ANSWER:

Correct

Lateralgenetransferisthephysicaltransferofagenebetweendistantlyrelatedlineages.

Chapter27PreTestQuestion2

PartA

Howdoesthelargeamountofgeneticvariationobservedinprokaryotesarise?

Hint1.

Considerhowbacteriareproduce.Isthismodeofreproductionconsistentwithhighgeneticvariation?

ANSWER:

Correct

Theshortgenerationtimesandlargepopulationsizesinmostprokaryoticspecies,coupledwiththeirabilitytoexchangegenes,helpstoincreasegeneticvariabilitybeyondwhatwewouldexpectinasexuallyreproducingorganisms.

MisconceptionQuestion135

PartA

Whichofthefollowingprocessescontributestogeneticrecombinationinprokaryotes?

ANSWER:

Correct

Intransduction,bacteriophagescarrybacterialgenesfromonehostcelltoanother,producingarecombinantbacterialgenome.Readabouttheotherprocessesthatcontributetogeneticrecombinationinprokaryotes.

InheritanceofagenefromaparentInheritanceofagenethroughmeiosisPhysicaltransferofagenefromaspeciesinonelineagetoaspeciesinanotherlineage.Inheritanceofagenethroughmitosis

Themutationrateinprokaryotesismuchhigherthanineukaryotes.Theyhaveextremelyshortgenerationtimesandlargepopulations.TheycanexchangeDNAwithmanytypesofprokaryotesbywayofhorizontalgenetransfer.Theyhavearelativelysmallgenome.Thesecondandthirdanswersarecorrect.

MutationMeiosisTransduction

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MakeConnections:BacterialConjugationandBinaryFissionCopy

Geneticvariationiscrucialtonaturalselectionandevolution,andthegreatsuccessofbacteriaisdue,inpart,totheextensivegeneticvariationfoundinbacterialpopulations.Thisgeneticvariationexistsdespitethefactthatbacteriareproduceasexually.Clickonthefigureonthelefttoreviewhowbacteriareproducethroughbinaryfission.Clickonthefigureontherighttolearnaboutconjugation,oneofseveralmechanismsthatallowsforgeneticexchangeamongbacteria.

PartAReviewingbinaryfissioninbacteria

Thefigureshowshowbacteriareproducethroughbinaryfission.

Dragthetermsonthelefttotheappropriateblanksontherighttocompletethesentences.

ANSWER:

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Correct

Bacteriareproducethroughbinaryfission.

Duringbinaryfission,theDNAinthebacterialchromosomeisreplicated,andonecopyispassedtoeachdaughtercell.Althoughplasmids(small,circularDNAmoleculesseparatefromthemainbacterialchromosome)arenotshowninthefigure,anyplasmidsinabacterialcellarealsoreplicatedandpassedtoeachdaughtercellduringbinaryfission.MutationsthatariseduringDNAreplicationareonesourceofgeneticvariationinbacterialpopulations.Therapidreproductionandlargesizesofmanybacterialpopulationscanyieldconsiderablegeneticvariationdespitealowmutationrate.

PartBHowdobinaryfissionandconjugationcontributetothespreadofantibioticresistanceinbacteria?

TheasexualreproductionofbacteriadescribedinthePartAfiguremayseemtosuggestthatallbacterialcellswithinapopulationshouldbethesame.Yetbacterialpopulationspossessconsiderablegeneticvariation.Youhaveseenthattwosignificantsourcesofgeneticvariationinbacteriaare:

mutationsthatariseduringDNAreplicationgeneticexchangeduringbacterialconjugation

Geneticvariationhasallowedmanybacteriatoevolveresistancetoantibiotics,andconjugationplaysaparticularlyimportantroleinthespreadofantibioticresistancefromonebacterialspeciestoanother.

LiketheFplasmid,theRplasmid(Rstandsforresistance)mayallowbacteriatoinitiateconjugation.TheRplasmidcontainsgenesforantibioticresistance.Duringconjugation,theRplasmidanditsantibioticresistancegenesaretransferredfromthedonorcelltotherecipientcell.

Thegraphbelowshowshowantibioticresistancecandevelopinapatientwithabacterialinfection.Noticethatthebacteriacountdropswhenantibiotictherapyisstarted,butthenrisesagainasresistancespreadsthroughthepopulation.

Dragthelabelstotheirappropriatelocationsontheconceptmapbelowtoexplorethelinksbetweenantibioticresistance,binaryfission,and

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conjugation.

ANSWER:

CorrectAntibioticresistanceinbacterialpopulationshasfollowedcloseupontheheelsofthewidespreaduseofantibiotics.

Asantibioticresistantbacteriathriveandsensitivebacteriadie,theproportionofresistantcellsinapopulationincreasesdramatically.Theseresistantcellscontinuetoundergobinaryfission,resultinginaninfectionthatisdifficulttotreat.Theabilityofbacterialpopulationstoevolveresistancerequiresgeneticvariation.Mutationisonesourceofgeneticvariation.Thelargepopulationsizesandrapidreproductionofbacterialpopulationsmeansthatevenwithalowmutationrate,asignificantnumberofmutationsareseeninbacterialpopulations.Someofthesemutationscontributetoantibioticresistance.Processessuchasconjugationallowforgenestobeexchangedamongbacteria.Becauseconjugationcanoccurbetweenbacterialcellsofthesamespeciesorofdifferentspecies,antibioticresistancesometimesspreadssurprisinglyeasilyfromonespeciesofbacteriatoanother.AsingleRplasmidmayhavegenesthatprovideresistancetotenormoredifferentantibiotics.Thisisespeciallyproblematicwhenbacteriathatareserioushealththreatsbecomeresistanttomultipleantibiotics.Forexample,methicillinresistantStaphylococcusaureus(MRSA)infectionsarecausedbybacteriathathaveevolvedresistancetomostoftheantibioticsthatwereonceusedtotreatstaphinfections.MRSAisbecomingincreasinglydifficulttotreat.

DiversityinBacteriaCopy

Bacteriaareextremelydiverseinstructureandinhowtheyobtainenergyandnutrients.Thisdiversityenablesbacteriatoliveinawidevarietyofenvironments.

PartAGramstaining

Classifyeachstatementorpictureasapplyingtogrampositivebacteria,gramnegativebacteria,orboth.TheGramstainingprocedureusesacrystalvioletdye.

Drageachitemtotheappropriatebin.

Hint1.Gramstaining

UsingamethodcalledGramstaining,scientistsclassifybacteriaintotwocategories:grampositivebacteriaandgramnegativebacteria.Gramstaininghasthreesteps:

1. Stainwithcrystalvioletdyeandiodine.2. Rinseinalcohol.3. Stainwithareddye,suchassafranin.

Hint2.HowthepeptidoglycanlayeraffectsGramstaining

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Gramstainingreliesondifferencesinthemakeupofouterstructuresinbacteria.

Inbacteriathathaveathickpeptidoglycanlayer,thepeptidoglycantrapsthecrystalvioletdyeinthecytoplasmofthebacteria.Thecrystalvioletcannotberinsedawaywithalcoholandmasksthereddyethatisaddedlater.Therefore,thesebacteriaappearpurple.Inbacteriathathaveathinpeptidoglycanlayer,thecrystalvioletdyeiseasilyrinsedawaywithalcohol,allowingtheaddedreddyetostainthebacteriaredorpink.

Hint3.Whataretheouterstructuresofgrampositiveandgramnegativebacteria?

Labeltheouterstructuresofgrampositiveandgramnegativebacteriainthediagrambelow.

Dragthelabelstotheirappropriatelocationsonthediagram.Labelscanbeusedonce,morethanonce,ornotatall.

ANSWER:

ANSWER:

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Correct

Gramstainingisatechniqueforclassifyingbacteriabasedondifferencesinthestructureoftheircellwalls.Gramnegativebacteriaandgrampositivebacteriabothhaveaplasmamembranesurroundedbyacellwallthatcontainspeptidoglycan.However,thecellwallofgramnegativebacteriaiscomposedofathinlayerofpeptidoglycanandanoutermembrane,whereasthecellwallofgrampositivebacteriaiscomposedofathicklayerofpeptidoglycan.Gramnegativebacteriaappearredorpinkbecausethealcoholrinsewashesawaythecrystalvioletdye.Grampositivebacteriaappearpurplebecausethealcoholrinsedoesnotwashawaythecrystalvioletdye.

PartBNutritionalmodesofbacteria

Labelthediagrambelowtoshowtherelationshipbetweennutritionalmodesofbacteria.

Dragthelabelstotheirappropriatelocationsonthediagram.

Hint1.Canyoudefinethetermsrelatingtonutritionalmodesofbacteria?

Dragthetermsonthelefttotheappropriateblanksontherighttocompletethesentences.

ANSWER:

Hint2.Whatistherelationshipbetweennutritionalmodesinbacteria?

Identifythetruestatementsaboutthenutritionalmodesinbacteria.

Selectallthatapply.

ANSWER:

ANSWER:

Allphototrophsareheterotrophs.Heterotrophsmaybechemotrophsorphototrophs.Autotrophsmaybechemotrophsorphototrophs.Allautotrophsarechemotrophs.Phototrophsmaybeautotrophsorheterotrophs.Chemotrophsmaybeautotrophsorheterotrophs.Allchemotrophsareautotrophs.Allheterotrophsarephototrophs.

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Correct

Somebacteriaobtainenergyfromlight(phototrophs),whereasotherbacteriaobtainenergyfromchemicals(chemotrophs).Autotrophs(literally"selffeeders")requireonlyaninorganicsubstance,suchascarbondioxide,astheircarbonsourceheterotrophs(literally"otherfeeders")requireatleastoneorganicnutrientastheircarbonsource.

PartCCharacteristicsofAzotobacter

Azotobacterisagenusofbacteriathatliveinsoilandhavethefollowingcharacteristics:

Theyarebacilli.Theyaregramnegative.Theyareobligateaerobes.Theycanfixnitrogen.(Unlikesomeothernitrogenfixingbacteria,whichassociatewiththerootsofplants,Azotobacterspeciesarefreeliving.)

SelectthefourstatementsthataretrueforbacteriainthegenusAzotobacter.

Hint1.Gramstaining

UsingGramstaining,scientistsclassifybacteriaintotwocategories:grampositivebacteriaandgramnegativebacteria.Thecellwallofgrampositivebacteriacontainsathicklayerofpeptidoglycan,whichretainsthecrystalvioletdyeusedinthefirststepofGramstaining.Thecellwallofgramnegativebacteriacontainsathinlayerofpeptidoglycan,whichallowsthecrystalviolettobewashedaway,revealingthereddyeusedinthethirdstepofGramstaining.

Hint2.Shapesofbacteria

Bacteriamaybespherical(cocci),rodshaped(bacilli),orspiral.Coccimayoccursingly,inpairs,inchains,orinclusters.Bacilligenerallyoccursinglybutmayalsobefoundaschains.Spiralbacteriacantaketheformoflongcoils,commas,orcorkscrews.

Hint3.Canyoudefinethetermsrelatingtotheroleofoxygeninmetabolism?

Dragthetermsonthelefttotheappropriateblanksontherighttocompletethesentences.Notalltermswillbeused.

ANSWER:

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Hint4.Nitrogenfixation

Inaprocesscallednitrogenfixation,somebacteriacanconvertatmosphericnitrogen(N2)toammonia(NH3).Bacteriacapableofthisprocesscanthenincorporatethe"fixed"nitrogenintoaminoacidsandotherorganicmolecules.

ANSWER:

Correct

Azotobacterisagenusofrodshapedbacteria(bacilli).AfterGramstaining,bacteriainthisgenusappearpinkduetothethinpeptidoglycanlayerintheircellwall.Theyrequireoxygenforcellularrespirationandcanconvertatmosphericnitrogentoammonia,whichtheyincorporateintoaminoacidsandotherorganicmolecules

Chapter27Question22

PartA

Matchthenumberedtermstothedescriptionthatfollows.Chooseallappropriateterms.1.autotroph2.heterotroph3.phototroph4.chemotrophaprokaryotethatobtainsbothenergyandcarbonasitdecomposesdeadorganisms

ANSWER:

TheycancarryoutanaerobicrespirationinanenvironmentthatlacksO2.Theyareshapedlikerods.Theyhavetheappearanceofcoilsorcorkscrews.TheyuseO2.TheyappearpurpleafterGramstaining.Theyhavearelativelythinlayerofpeptidoglycanintheircellwall.Theycanconvertatmosphericnitrogentoammonia.Theyrequireaminoacidsorotherorganicmoleculesasasourceofnitrogen.TheyarepoisonedbyO2.

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Correct

Chapter27Question4

PartA

Thepredatorybacterium,Bdellovibriobacteriophorus,drillsintoapreybacteriumand,onceinside,digestsit.Inanattackuponagramnegativebacteriumthathasaslimycellcovering,whatisthecorrectsequenceofstructurespenetratedbyB.bacteriophorusonitswaytotheprey'scytoplasm?1.membranecomposedmostlyoflipopolysaccharide2.membranecomposedmostlyofphospholipids3.peptidoglycan4.capsule

ANSWER:

Correct

Chapter27Question34

PartA

Thetermitegutprotist,Mixotrichaparadoxa,hasatleasttwokindsofbacteriaattachedtoitsoutersurface.Onekindisaspirochetethatpropelsitshostthroughthetermitegut.AsecondtypeofbacteriasynthesizesATP,someofwhichisusedbythespirochetes.ThelocomotionprovidedbythespirochetesintroducestheATPproducingbacteriatonewfoodsources.Whichterm(s)is(are)applicabletotherelationshipbetweenthetwokindsofbacteria?1.mutualism2.parasitism3.symbiosis4.metaboliccooperation

ANSWER:

Correct

2and44only1only1and31,3,and4

4,3,1,21,3,4,24,2,3,12,4,3,11,4,3,24,1,3,2

2,3,and41only2and31,3,and41and2

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Chapter27PreTestQuestion5

PartA

Whichstatementistrueaboutobligateanaerobes?

Hint1.

Thinkaboutittheyareobligatedtobeanaerobic.

ANSWER:

Correct

Someobligateanaerobesliveexclusivelybyfermentationothersextractchemicalenergybyanaerobicrespiration,inwhichsubstancesotherthanO2acceptelectronsatthe"downhill"endofelectrontransportchains.

Chapter27PreTestQuestion10

PartA

Bioremediationis_____.

Hint1.

Whichofourmistakesarewetryingtoremedyusingbioremediation?

ANSWER:

Correct

Thisisthegeneraluseofthetermbioremediation.

Chapter27PreTestQuestion4

PartA

Bacteriathatlivearounddeepsea,hotwaterventsobtainenergybyoxidizinginorganichydrogensulfidebelchedoutbythevents.Theyusethisenergytobuildorganicmoleculesfromcarbonobtainedfromthecarbondioxideinseawater.Thesebacteriaare_____.

Hint1.

Considerthesourceofenergyfortheconstructionoforganiccompounds.

TheywilluseO2ifitispresent,butcanobtainenergybyfermentationifneeded.Theyobtainenergybyoxidizingferrousions.TheyuseO2forcellularrespirationandcannotgrowwithoutit.Theyliveexclusivelybycellularrespirationorbyanaerobicrespiration.TheyarepoisonedbyO2.

theuseofbiologicalprocessestoremedydiseasesthemodificationofprokaryotesforindustrialpurposestheuseofprokaryotesinproducingtransgenicorganismstheuseoforganismstoremovepollutantsfromtheenvironmenttheuseofprokaryotesinproducingpharmaceuticalproducts

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ANSWER:

CorrectTheyuseinorganicmolecules(inredoxreactions)forenergy,andcarbondioxideforcarbon.

ScoreSummary:Yourscoreonthisassignmentis102%.Youreceived5.88outofapossibletotalof5.75points.

photoautotrophschemoautotrophsphotoheterotrophschemoheterotrophs