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Livingthings:Cells

Thecellisthesmallestunitcapableoflivinganindependentexistence.Mostcellscontainanucleuswhichcontrolsthewaytheywork;theonlycellsinthehumanbodywithnonucleiaretheredbloodcells.Cellsarethebuildingunitsoflivingthingsandmostofthemaretiny.Animalandplantcellshavesimilarinternalstructuresandcomposition,butplantcells,becauseoftheircellulosewalls,haveamorerigidstructure.Animalcellslackchloroplasts,whicharethestructureswhichplantsuseforphotosynthesis.

Essentialfeaturesofeachcellare:themembrane,whichenclosesthecellandrestrictstheflowofsubstancesinandout;andcytoplasm,awateryjellycontainingstructureswhichcarryoutproteinsynthesis,aswellasDNAwhichformsthehereditarymaterial.

Plantsandanimalsgrowbecausetheyaddmaterialtothemselves.Somestudentsmayhavedifficultyunderstandingthis;theymayimaginethatplantsandanimalsgrowbecausetheyswell,ratherlikeaballoon.Thisistrue,inpart,ofplants:individualcellsfillwithwaterandswelltoproducetherapidelongationofshootsandroots.Butmostgrowthisbycelldivision–thesplittingofcellstoincreasethenumber(butnotthevolume)ofcells.Thesubsequentswellingofthenewcellsleadstopermanentgrowth.Someofthesenewcellswillbecomespecialisedstructures.

Cellsaregroupedtogethertoformatissue.Thereareseveralkindsoftissue,eachconsistingofcellsofaparticularkindboundtogether.Somecommonformsoftissueinanimalsaremuscletissue,nervoustissue,epithelialtissue(whichlinestheinsideofthestomachandotherbodyorgans),connectivetissue(whichholdspartstogether)andreproductivetissue,whichproducesthespermandeggs.

Living things:Cells

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unit 1

Livingthings:Cells

Lesson1:DiscoveringcellsLessonpreparationObjectives

identifycells useamicroscopetolookatsomeplantandanimalcells

Science skillsusingamicroscopetolookatcells

EquipmentWarmup: athinsliceofcorkorpreparedslides,amicroscopeActivity1 amicroscope,twomicroscopeslides,twocoverslips,tweezers,largepins,asharpknife,twodroppers,iodinesolution,apieceofonionActivity2 amicroscope,amicroscopeslide,acoverslip,adropper,tweezers,methyleneblue,acleanwoodentoothpick

Key words

cells: thebasicunitsfromwhichlivingthingsarebuiltmicroscopic: somethingsosmallitcanonlybeseenwithamicroscopemulti-cellular: describesalivingthingbuiltfrommanycells;animalsaremulti-cellularunicellular: describesalivingthingthatconsistsofasinglecell

Background informationThecellisthesmallestunitcapableoflivinganindependentexistence.Cellsarethebuildingunitsoflivingthings.Mostofthemaretiny.Animalandplantcellshavesimilarinternalstructuresandcomposition,butplantcells,becauseoftheirrigidcellulosewalls,haveamorerigidstructure.

LessonplanWarm upTellthestudentsaboutRobertHooke:RobertHookewasbornin1635.Hewasagreatscientist–anastronomer,aphysicistandabiologist.HisbookcalledMicrografiacontainshisobservationsandhisdrawings.Lookingatathinsheetofcork,hesawtinyboxes.Theyremindedhimofthelittleroomsinamonastery,sohecalledthem‘cells’.Nearlytwohundredyearslater,MatthiasSchleidenfirstsuggestedthatallplantsaremadefromcells.ThestudentscouldcopyRobertHooke’sactivity,butyouwillneedtoslicecorkextremelythinly.Forthisyouwillneedanextremelysharpblade–forteacheruseonly–orobtainpre-preparedslides.Askthestudentswhattheyknowaboutcellsandtheirimportance.Howmanydifferentbodycellscanyouname?Whatdothesedifferentcellslooklike?Whatistheirfunction?Howdocellsworktogether?Forexample,thecellsinourmusclesandbones?

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Livingthings:Cells

Activity 1 p11Studentslookatpieceofonionunderthemicroscopetoobserveplantcells.

Activity 2 p12Studentslookatsomecellsfromtheinsideoftheircheektoseewhatanimalcellslooklikeunderthemicroscope.

ExtensionThislessoninvitesstudentstofindoutmoreaboutthedifferentsortsofanimalcells.TheycouldbegintheirinvestigationontheInternetwithanumberofsciencewebsites,especiallythosethatshowthemthevarietyofunicellularlife.

Concluding the lesson p13

WhatyouhavelearntanswersAlllivingthingsarebuiltfromcells.Ahumanbodyismulti-cellular–itisbuiltfrombillionsofcells.Thesmallestlivingthingsarejustonecell–theyarecalledunicellularorganisms.Cellsaremicroscopic;theyaresosmalltheycanonlybeseenusingamicroscope.

Checkyourprogressanswers1 thebuildingblocksoflivingthings2 allthecharacteristicsoflife:growth,movement,feeding,respiration,feeling,excretionand

reproduction3 Unicellularorganismshavejustonecell;multi-cellularoneshavemanycells.

AfterthelessonWorkbook p4–5

Answers1 amicroscopic bcell cunicellular dmulti-cellular2 ahumancheekcell bmicro-organism conionskincells3 atube beyepiece cfocusingknob dobjectivelens elimb fstage gbase hmirror4 awithbothhands

bcoarsefocusingknobtowindtheobjectivelensup;finetofocustheimageassharplyaspossible

Lesson2:ComparingplantandanimalcellsLessonpreparationObjectives

identifysomeofthefeaturesofplantandanimalcells describesimilaritiesanddifferencesbetweenplantandanimalcells

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Lesson1:DiscoveringcellsLesson2:Comparingplantandanimalcells

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16 Livingthings:Cells

Science skillsidentifyingcharacteristics

EquipmentExtension: researchfacilities

Key words

cellmembrane: thethinlayerthatenclosesacellcellulose: thesubstanceinthecellwallsofplantsthatgivesthemstrengthchloroplasts: smallgreendiscsinplantcells;chloroplastscontainchlorophyll,thegreensubstancethatplantsusetotraptheenergyofsunlightcytoplasm: theliquidthatfillsmostofthespaceinsidealivingcellnucleus: thepartofalivingcellthatcontrolsitslifeprocessesvacuole: aliquid-filledspaceinacell

Background informationAllcellshaveamembrane,whichenclosesandrestrictstheflowofsubstancesinandout,andajellylikematerialcalledcytoplasmwithinit.Thecellsofplants,bacteriaandfungipossessarigidcellwallthatprotectsthecellandmaintainsitsshape.Mostcellscontainanucleus;theonlycellsinthehumanbodywithnonucleiaretheredbloodcells.Plantcellshaverigidcellulosewallsandchloroplasts–thephotosynthesisingstructures;animalcellsdonot.

LessonplanWarm upWhatdoyourememberfromthelastlessonaboutcells?Whyaretheycalledthebuildingblocksoflife?Whyaretheycalledcells?Whatdotheyresemble?Arecellsallthesame?Howaretheydifferent?Namesomeofthecellsinthehumanbody.Plantandanimalcellsaredifferent.Whymightthatbe?Whatcanplantsdothatanimalscan’t?Whatdowemeanbyphotosynthesis?Whatisthechemicalthatissoimportantforphotosynthesis?I’llgiveyouaclue–it’sgreenincolour.Becausetheylackthisvitalchlorophyll,animalsareunabletophotosynthesiselikeplantsandcannotmaketheirownfood.Butthereareotherdifferencesbetweenplantandanimalcells.

Activity 1 p14

AnswersPlantcell: nucleus,cytoplasm,cellmembrane,cellwall,chloroplast,largevacuoleAnimalcell: nucleus,cytoplasm,cellmembrane

ExtensionUsingillustrationsfrombooksandfromtheInternet,askstudentstodrawageneralisedplantandageneralisedanimalcell.Differentgroupscouldtackleeachkindofcell;andthenthetwocouldbecomparedtoseewhichstructuresareineachcellandwhicharemissing.

Lesson2:Comparingplantandanimalcells

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17Livingthings:Cells

Concluding the lesson p15

WhatyouhavelearntanswersPlantandanimalcellshaveanucleuswhichcontrolshowthecellworks.Thecellisfilledwithcytoplasm,whichismainlywater.Thecellissurroundedbyacellmembrane,whichholdsthecelltogetherandletsdifferentsubstancesinandout.Plantcellshaveastrongcellwallmadefromcellulose.Plantcellsalsohavegreenchloroplaststhathelptheplanttraptheenergyofsunlightandalargevacuolethatcontainschemicals.

Checkyourprogressanswers1 Itcontrolsthewaythecellworks.2 cellmembrane3 no4 spaceinsideacellfilledwithawaterysolution

AfterthelessonWorkbook p6

Answers1 Animal;acellmembrane bnucleus ccytoplasm2 Plant;acytoplasm bnucleus ccellmembrane dcellwall ecellvacuole fchloroplast3 largevacuole;cellwall;chloroplast4 acytoplasm bnucleus cchloroplast dcellmembrane

Lesson3:BuildingtissuesLessonpreparationObjectives

understandhowcellsreproduce knowthattherearedifferenttypesofcells knowthattissuesaremadeupofcellsandthatorgansaremadeupoftissues

Science skillsunderstandingcellreproduction

EquipmentWarmup: sheetsofwallpaperActivity2 achessboardandabagofriceExtension: longstripsofpaper,cardboardboxes

Lesson2:ComparingplantandanimalcellsLesson3:Buildingtissues

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Lesson3:Buildingtissues

Livingthings:Cells

Key words

differentiate: tobecomedifferentdivide: splittingintoparts;acellreproducesbydividingepithelial: theskinoroutertissueofabodyoranorganfoetus: ababydevelopinginthewombpregnant: expectingababy.Pregnancyisthetimeduringwhichababydevelopsintheuterussperm: malesexcellstissue: bodycomponentsmadefromcellsofonetype,muscletissueforexample

Background informationInbiology,anykindofcellularfabricthatoccursinanorganism’sbodyiscalledatissue.Thereareseveralkindsoftissue,eachconsistingofcellsofaparticularkindboundtogether–bycellwallsinplants,orbyakindofmatrixinanimals.So,forexample,nerveandmusclearedifferentkindsoftissuesinanimals.Anorganispartofthelivingbody,suchastheliverorthebrain,withaseparatefunctionorsetoffunctions.Someofthecommonformsoftissuearemuscletissue,nervoustissue,epithelialtissue(whichlinestheinsideofthestomachandotherbodyorgans),connectivetissue(whichholdspartstogether)andreproductivetissue,whichproducesthespermandeggs.

LessonplanWarm upHowmanydifferentorgansarethereinsideyou?Askapartnertolieonasheetofwallpaperanddrawroundthem.Nowdrawinasmanybodyorgansasyoucanintherightplaces.Haveyoufinished?Howmanydifferentorganscanyoufind?Someareinpairs,likekidneysandlungs.Somearesinglestructures.Tellmewhateachorgandoes.Whatisthefunctionofthebrain?Whatdoestheheartdo?Whatisspecialaboutthelungs?Dotheorgansalllookalike?No,theyaremadeupfromdifferenttissuesandtissueisthewordweusetodescribethematerialthatmakesuporgans.Tissuesaredifferentbecausetheycontaindifferentkindsofcell.

Activity 1 p16

Answers

Activity 2 p17Cellsdividetoreplacecellsthatarewornoutordamaged.Newcellsaremadebyothercellsdividingintotwo,growingtofullsizeanddividingagainandsoon.Thisishowalllivingthingsgrowandrepairthemselves.Inourbodies,morethan2millionbloodcellsaremadeeverysecondtoreplaceoldonesdyingatthatrate.Studentsuseachessboardtoworkouthowcellsdivideandmultiplyandhowmanystagesareneededtoproduceallthecellsinthehumanbody.

1 40weeks2 Itdividesagainandagain.

3 no4 Exampleanswer:muscles,nerves,blood.

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Activity 3 p17

Answers1d 2b 3c 4a

ExtensionReviewwhatthestudentshavelearntaboutthedifferentkindsofcells.Whatarethemostamazingfactstheyhavediscoveredaboutthemselvesandtheirbodies?Perhapsyoucouldproduceawallofamazingfactsaboutcells.Forexample,nervecellscanbeextremelylongandcanconductnerveimpulsesat160m/s.Cardiacmusclegoesonbeatingthroughoutourliveswithouteverfaltering.Thereare5billionredbloodcellsperlitreofblood.Theyleadahardlifeastheyareforcedathighpressurethrougharteries,veinsandcapillaries.Whitebloodcellsarefiercedefendersagainstinvadingbacteria,whilesomeofthemmaketheproteinthatformsascaboverdamagetoourbodies.Differentcellsaredifferentshapes.Wearegoingtomakeatelevisiongametoidentifydifferentcells.Here’showtodoit.Firstyouneedalongstripofpaperonwhichyoudrawallthedifferentcelltypesyoucanthinkof.Youcanhavesomeduplicates.Youneedaboxtothreadthestripofpaperthrough.Maketwoslotsintheboxandslipthepaperthroughthefirstoneandbackthroughthesecond,sothatwhenyoupullonthepaperitslidesacrossthefrontasifacrossatelevision.Nowyou’rereadytoplaythegame.Askafriendtowatchthecellsslidingacrossinfrontofthemandtonamethetypeofcellbeforeit’sgoneandseehowmanytheycanasyouslidethepaperthroughslowlyandthenasyouslideitthroughfaster.

Concluding the lesson p18

WhatyouhavelearntanswersAwomanbecomespregnantwhenaspermfertilisesheregg.Thefertilisedegggrowsasitscellsdividetomakemoreandmorecells.Asthenumberofcellsgetsbiggerandbigger,thecellsdifferentiatetobecomebloodcells,musclecellsandothercelltypesandafoetusisformed.Atissueisagroupofcellsofonetypethatworktogethertodoajob.Muscletissueproducesmovement;epithelialtissuelinessurfacesinthebody.

Checkyourprogressanswers1 dividemeanstosplittocreatemorecells;differentiatemeanstodevelopindifferentways2 agroupofcellsthatworktogethertodothesamejob3 muscle;nervous;epithelial;connective

AfterthelessonWorkbook p7–8

Answers

Lesson3:Buildingtissues

1 Studentscompletethediagramandthetabletoshowhowcellsdivideandhowmanycellsareproducedineachgeneration.

2 afalse btrue cfalse dtrue

3 aepithelial bdivide cdifferentiate4 anervecell bmusclecells

cepithelialcells dredbloodcells

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