组织学自我测试题第一部分

SELF-ASSESSMENTINHISTOLOGYQUESTIONS一,THECELL1The'fluidmosaic'modelofmembranestructureproposesthattheplasmamembraneconsistsofabilaterofphospholipidmoleculesseparatedbyalayerofprotein.(F)2Ingeneral,hydrophobic(lipophilic)moleculesareabletodiffusefreelyacrossmembranes.(T)3Thecholesterolmoleculeswhichareassociatedwithplasmamembranesformtheso-calledglycocalyxofsomeeukaryoticcells.(F)4Thetrilaminateappearanceoftheplasmamembranewhenviewedwithelectronmicroscopyisexplicableintermsofthe'dynamicpores'modelofmembranestructure.(T)5Largemolecular-weightpolysaccharidemoleculesform'dynamicpores'fortransportofmoleculessuchassodiumionsintocells.(F)6Lipid-solublemoleculessuchasethanolcrossmembranesbytheprocessdescribedas'facilitateddiffusion'.(F)7'Facilitateddiffusion'permitsthetransportofmoleculesacrossmembranesagainstaconcentrationgradient.(F)8The'sodiumpump'isanexampleofanactivetransportmechanismsinceitiseffectiveagainstaconcentrationgradient.(T)9Onlyactivemembranetransportprocessesareenhancedbyincreasingtheplasmamembranesurfacearea.(F)10Phagocytosisisthereverseprocessofendocytosis.(F)11Primarylysosomesareelectron-lucentstructuresboundedbyamembrane.(F)12Phagosomesarealsoreferredtoaslipofuscingranules.(F)13Autophagyisoneoftheprocessesinvolvedinthecontinuousturnoverofcytoplasmicorganelles.(T)14Multivesicularbodiesareastorageformoflysosomalprecusors.(F)15Alkalinephosphataseactivityisausefulhistochemicalmarkerforlysosomes.(F)16Cellularenzymesaresubjecttowearandtearandarecontinuouslyturnedover,whereasstructuralproteinsinthecellarecompletelystable.(F)17MessengerRNAsynthesisinvolvestranscriptionofpartofthegenome.(T)18RibosomalRNAissynthesisedinthenucleus.(T)19Eachribosomeconsistsoftwosubunits,oneofwhichiscomposedofRNAandtheothercomposedofribosomalproteins.(F)20UnlikemessengerandribosomalRNA,transferRNAissynthesisedbyribosomes.(F)21Acellwithoutanucleuscouldnotbeinvolvedinproteinsynthesis.(F)22TheprincipalnuclearconstituentsareDNA,RNAandprotein.(T)23HeterochromatinrepresentsthatpartofthegenomewhichisactivelyinvolvedinRNAsynthesis.(F)24Barrbodiesrepresentaformofheterochromatininthenucleiofcellsfromnormalfemales.(T)25Aprominentnucleolusisusuallyindicativeofahighdegreeofcellularmetabolicactivity.(T)26Thenucleusisboundedbytwolayersofmembraneseparatedbyanarrowspace.(T)27Radio-isotopelabellingstudieshaveshownthatnucleolipassfromthenucleustothecytoplasmviaporesinthenuclearenvelope.(F)28Thediameterofnuclearporesisaboutthesameasthatofmitochondria.(F)29Ribosomesareoftenattachedtothesurfaceofendoplasmicreticulumbutmayalsoliefreeinthecytoplasm.(T)30Extensiveroughendoplasmicreticulumisusuallyfoundincellshighlyactiveinproteinsynthesiswhereasextensivesmoothendoplasmicreticulumischaracteristicofcellshighlyactiveinlipidsynthesis.(T)31Exocytosisistheusualmeansofsecretionofproteinsandotherlipid-solublematerials.(F)32TheGolgiapparatusisaspecialisedareaofroughendoplasmicreticuluminvolvedinglycolipidsynthesis.(F)33TheGolgiapparatusisresponsibleforpackaginglargemolecularweightsecretoryproductspriortotheirsecretionbyexocytosis.(T)34SecretoryproductspassfromtheendoplasmicreticulumtotheGolgiapparatusintheformoflysosomes.(F)35TheGolgiapparatusischaracteristicallylocatedimmediatelybeneaththeplasmamembrane.(F)36Cellularrespirationoccursinthecytosol,mitochondriaandribosomes.(F)37Eukaryoticcellswithoutmitochondriaareincapableofaerobicmetabolism.(T)38Theenzymesofthetricarboxylicacidcycleconstitutethe'respiratoryassemblies'andarelocatedonthemitochondrialcristae.(F)39Mitochondriaarecapableofproteinsynthesis.(T)40Glycogenischaracteristicallystoredwithinmitochondriawhereitformsso-calledmatrixgranules.(F)41Allcellularmovementisprincipallymediatedbyrearrangementoftheproteinsubunitsoftheglycocalyx.(F)42Microfilamentsconsistofminuteproteinstrandssmallerindiameterthanglycogengranules.(T)43Microtubulesarethoughttoconstituteaspecialisationoftheendoplasmicreticulum.(F)44Microtubulesareofapproximatelythesamediameterasmicrofilaments.(F)45Withelectronmicroscopy,microtubulescanbedistinguishedfrommicrofilamentsbytheirextensivebranching.(F)46Normalmitosisresultsintheproductionoftwodaughtercellswhicharegeneticallyidenticalbutwhichmaynothaveidenticalcytoplasmicconstituents.(T)47Inthecellcycle,theG1phaseisthesameasinterphase.(F)48Afterreplicationofthegenome,thecellimmediatelyentersmitosis.(F)49AcellwhichisintheG。phaseofthecellcyclemayre-enterthecellcycleunderappropriatecircumstances.(T)50Sincetheprocessofmitosisusuallytakesmanydaystocomplete,mitosisfiguresareobservableinverylargenumbersintissuesmadeupofrapidlydividingcells.(F)51Somatic(body)cellsusuallycontainthediploidnumberofchromosomes.(T)52Inhumans,eachdiploidcellcontains46homologouspairsofchromosomes.(F)53DuringtheSphaseofthecellcycle,eachchromosomeisduplicatedsuchthatattheonsetofmitosiseachchromosomeconsistsoftwochromatidsjoinedatthekinetochore.(T)54Duringmitoticanaphase,themembersofeachhomologouspairofchromosomesmigratetooppositeendsofthespindle.(F)55Duringmitosis,apairofcentriolesislocatedateachpoleofthemitoticspindle.(T)