9 Plants : Parts and Functions - SelfStudys
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Transcript of 9 Plants : Parts and Functions - SelfStudys
9Plants:PartsandFunctions Whatkindofplantshaveyouseenathomeandoutside?Youmusthaveobservedavarietyofplants;somearebigandsomearesmall.Wecanfindplantsnearourhome,intheschoolcampus,onthewaytoschool,intheparksandalmosteverywhere.
•Areallplantssimilar?
•Whatarethesimilaritiesamongthem?
Letusgettoknowmoreaboutplants,especiallyabouttheirpartsandfunctions.Partsofplants
Weknowthatwehavedifferentpartsinourbody.Inthesamewayplantsalsohavedifferentparts.Doyouknowthem?Hereisaplant.Trytonameitsparts.Whichplantisthis?
Fig.1
In this chapter, Let us try to understand about different parts of plants throughactivities. For this,makegroupsof4-5students.Eachgroupwillcollect5to6differenttypesofplantsalongwiththeirroots.Youcancollectdifferentsmallplantsfromyourgardenorsurroundingsbutbecarefulnottodamagetoomanyplants.Activity-1:Identificationofplantparts
Observe the collected plants and try to identify their parts. Take the help of Fig. 1 andwrite yourobservationsinTable1givenonthenextpage.
Ifyoudon’tknowthenameofanyoftheplantsyoucangivethemanumber.Youcantakethehelpofyourteacher,agardenerorsomeoneelsetofindthenameoftheplant.BasedontheobservationsintheTable1,letusdiscussthefollowingquestions.
Didyoufindanyplantwhichdoesnothaveroots?
Aretheleavesofalltheplantssimilarinsize?
Isthereanyplantwithoutflowers?
Whatarethecommonpartsthatyouobserveinallplants?
Anotchinatreewillremainthesamedistancefromthegroundasthetreegrows.
Table1
S.No Nameoftheplant RootYes/No
StemYes/No
LeavesYes/No
FlowerYes/No
1 Tridaxplant Yes Yes Yes Yes
2 PlantNo.2
3
4
5
Fig.2(a) Fig.2(b)
Therearevariationsinthesizeandshapeofplantsbutgenerallyallplantshaveroots,stemsandleaves.Haveyouever thoughtabout the importanceof leaf,stemandroots inplants?What is theroleofplantparts?Letustrytounderstandthesethings.
Roots:DifferenttypesofrootsObservetherootsoftheplantsyoucollected.Howarethey?
Doallplantshavesimilartypesofroots?
Isthereanydifference?
Compare the rootsof yoursampleplantswithFig.2(a)andFig.2(b).Write 2(a) or 2(b), in the column‘rootsaresimilarto’,accordingtoyourobservations.
Table-2S.No NameofthePlant RootsaresimilartoFig
1 Tridaxplant 2a
2 PlantNo.2
3
4
5
Bananaoilismadefrompetroleum.
•InFig.2(a),howdoesthemiddlerootlooklike?
•ComparethismiddlerootwiththeremainingrootsoftheplantshowninFig.2(a).
•DoyoufindanysuchmainrootinplantshowninFig.2(b)?Howaretherootsofthisplant?
•DoyoufindanyotherdifferencesbetweenFig.2(a)andFig.2(b)
Insomeplants, themainrootbecomesthickandhas thinrootlets.Thismainroot isknownas taproot(Fig.2(a))andtherootletsarecalledlateralroots.
Insomeplantswefindsmallhair-likerootsarisingfromthebaseofthestem.Thistypeofrootsystemisknownasfibrousroot.Hereallrootsaresimilar(Fig.2(b))andthereisnomainroot.
Functionoftheroots•Inactivity-1,couldyoupullouttheplantseasilyfromthesoil?Orwasitdifficult?Thinkwhy?
Observetherootsoftheplants;soilisattachedtotheroots.Rootshelptofixtheplanttightlytothesoil,sowecannoteasilyuproottheplant.
Doyouknowwhytherootspenetratedeepintothesoil?Activity-2:AbsorptionofWater
Taketwoglasstumblersfilledwithwater.Collecttwoplantshavingsoftstems,alongwiththeirroots.
Plantsinwaterwithoutink
Plantsinwaterwithredink
Fig.3
84%ofarawappleand96%ofarawcucumberiswater.
Addcolour(redink)inoneofthetumblers.Placetheplantsineachofthetumbler(Fig.3).Letthembefor2–3hoursandthenrecordyourobservations.
•Whydoyouthinkweaddedredinkinonetumbler?
•Didyouseeanyredspotsinthestemorotherpartsofanyoftheplants?
•Whydidredspotsappearonthestemorflower?
Wecanconcludethatrootshelpintakingupofwaterfromthesoil.Theydothisbyabsorption.Mineralspresentinthesoilarealsoabsorbedalongwiththewater.
Midrib
Lamina
Veins
Petiole
Leafbase
Doyouknow?
Some plants store food in roots and stems. Some plants like radish, carrot, beetroot store foodmaterials in their roots.These rootsbulgeoutandcalled tuberous roots.Canyougivesomemoreexamples.Carrot,sweetpotatoareeatenevenwhenraw!
Fig.4
PartsofaleafLeavesareanother importantpartofplants.Mostplants thatwesee inoursurroundingshavedifferenttypesofleaves.
Fig.5
Observethegivenpictureofaleafanditsparts(Fig.5).
•Whereistheleafattachedtothestem?
•Whatistheflatportionoftheleafcalled?
•Whatdoyoucallthesmalllinelikestructureintheflatportionoftheleaf?
•Whichpartconnectsleaflaminawithstem?
Aleafcontainsleafbase,astalklikestructurecalledpetioleandlamina.
Pistilshavethreeparts–thestigma,thestyle,andtheovary.
Activity-3:Areallleavessame?
Observetheleavesoftheplantsthatyoucollectedinactivity1.Howarethey?Arealltheleavesofthesamesizeandshape?SeeFig.5showingaleafanditsparts.
Comparetheleavesoftheplants,collectedinactivity1,withFig.5.Writeyourobservationsintable3.Youcanalsodrawwhatyouseeinthe‘shape’and‘edge’columnsifdescribingisdifficult.
Table3
S.NoNameoftheplant
LeafbaseYes/No
PetioleYes/No
LaminaYes/No
Shapeoftheleaf
Edgesoftheleaf
1 Tridaxplant
2
3
4
5
•Whatarethecommonpartsthatyouobserveinallleaves?
•Doalltheleaveshavethesameshape?Venation
Observe the leaf lamina carefully.What do you see? Youmay see some thin line- like structuresspreadovertheleaf.Activity-4:Venation
Theleaflaminausuallyconsistsofamidrib,veinsandveinletsarrangedintheformofanetwork.Tounderstandthisvenationletusdoanactivity.
Putaleafunderawhitesheetofpaperorasheetinyournotebook.Holdthetipofapencilflatandrubitonthepaper.Didyougetanyimpression?Isthispatternsimilartothatontheleaf?
Theselinesontheleafarecalledveins.Thelongveinpresent inthemiddleofthelaminaiscalledmidrib.Thebranchesarisingfromthemidribarecalledveinsandtheevenfinerdivisionsareveinlets.Thearrangementofveinsinthelaminaiscalledvenation.Venationactsasaskeletonoftheleafandgiveitashapeandsupport.Thinkwhatwouldhappeniftherearenoveinsintheleaf!
Petalsareusuallycolorful,andtheyattractinsectsandbirdsthathelpwithpollination.
Activity-5:TypesofVenation
Observe the venation of the leaves that you collected in activity 1. Now compare them with thevenationsoftheleavesshowninFig.6.
Recordyourobservationsintable4.
ReticulateParallel Parallel
(web-like)venation venation
Fig.6
Table4S.No Plant Venation(Reticulate/Parallel)
1
2
3
4
5
Nowcomparetheresultsobtainedintable2withtable4.
•Whattypeofrootsarethereinplantshavingparallelvenationintheirleaves?
•Whattypeofrootsarethereinplantshavingweb-likevenationintheirleaves?
•Isthereanyrelationbetweenvenationandrootsystem?
Youwillseethattheplantswithtaprootsystemhaveleaveswithweb-likeorreticulatevenationandplantswithfibrousrootshaveparallelvenation.
Functionsofaleaf Leavesplayanimportantroleinthelifeofplants.Plantsalsobreathelikeus.Doyouknowwhichpartoftheplantactsastheirnose?Activity-6:StomataObservation
Takeafleshyleaf.Peeltheouterlayeroftheleafandplaceitonaslide.Putadropofwateronitandobserveitunderamicroscope.Trytofindsomebeanshapedparts.
Fig.7
Pistilshavethreeparts–thestigma,thestyle,andtheovary.
ComparewhatyouseeunderthemicroscopewithFig.7.
Thebeanshapedpartthatyouseeintheleafactslikeournose.Thesearecalledstomata.Itisusefulintheexchangeofgasesbetweentheplantandatmosphere.
Doyouknow?...InWarangaldistrict,thereisatraditionalcottageindustrywherepicturesofvarioustraditional and mythological figures are drawn with bright colours on dried leaves. This artwork isfamousthroughouttheworld.
Activity-7:Transpiration
Do you know that excess water is removed in the form of vapours from the leaf surface. Tounderstandthisletusdothefollowingactivity.Chooseabright,summerdaytodotheactivity.
Fig.8
Selectawellwateredplantthathasbeengrowinginthesun.Enclosealeafybranchoftheplantinapolythenebag(Fig.8)andtieupitsmouth.Takeanotherpolythenebagofsamesizeandtieupitsmouthwithoutkeepinganyplant.Keepboththepolythenebagsinthesun.Afterafewhoursobservetheinnersurfaceofthebags.Whatdoyousee?
Arethereanydropletsofwaterinanyofthebags?Whichbaghasdroplets?Howdoyouthinktheyareformedthere?
Plantsreleaseexcesswaterintheirbodythroughstomataandsomeotherpartsaswell.Thewaterisreleasedintheformofvapourandthisprocessiscalledtranspiration.Thesevapourscondenseandareseen as droplets in the polythene bag. Think, what will happen if transpiration does not take place inplants.
Anotherleaffunctionisthepreparationoffoodfortheplantbytheprocessofphotosynthesis.Wewilldiscussmoreaboutthisinthenextclasses.
Stemprovidessupporttotheplant
ObservethestemportionofsomeplantsthatyoucollectedforActivity1Recordyourobservationsintable5.
Petalsareusuallycolorful,andtheyattractinsectsandbirdsthathelpwithpollination.
Table5
S.No NameoftheplantStemgrowsVertically/Horizontally
BranchesarePresent/Absent
•Doallplantshavestems.
•Arethestemsofallplantssimilar?
•Howisthestemoftheplantthatgrowshorizontally?
Leavesand flowersgrow from the stem. If youobserve carefully, youwill seea scar on the stemwheretheleafarises.Thestembranchesintosub-branchesandbearsleaves,flowersandfruits.Activity-8:Carryingfoodmaterial
Taketwosmallcuttingsfromasoftstemmedplant.Setthemuplikeyoudidinactivity2(Fig.9).Waitfor2-3hoursandrecordyourobservations.
•Whatdifferencesdidyoufindbetweenthestemofboththeplants?
•Doredspotsappearontheleavesorflowersofanyoftheplants?
Cutasmallsectionofthestemoftheplant,keptinredinkandwater,withasharpblade.Takethehelp of your teacher for this. Put it on a slide. Observe it under a microscope. Do you observe anycolouredportion?Now,cutthestemintotwohalvesvertically,fromtoptobottomObserveit.Doyouseeanycolouredportion?
Fig.9
The coloured ring like structure that you see act as a tube that carries water and food material
throughouttheplant.Thewaterabsorbedbytherootiscarriedthroughthestemtoallpartsoftheplant.
Fruitisreallythepartofaflowerinwhichseedsgrow.Cherries,apples,andevenmilkweedpodsarefruit.
Doyouknow?...Someplantslikepotato,turmeric,garlic,gingerandsugarcanestorefoodmaterialinthestemduetowhichthestembulgesinsize.Generallywethinkthatthesearealltubersorroots.Actuallytheyaremodifiedstems.
Fig10
Howcanyousaythatapotatoisstemalthoughitgrowsundertheground?Thinkitover.
Mostplantsaroundushaveroots,leaves,stemsandflowers.Allpartsoftheplantscarryoutsomefunctions, essential for the whole plant. There are diverse forms of plants in nature and plants adaptthemselvestothedifferentconditionsinnatureindifferentways.Forexample,whilestemsusuallysupporttheplantbody,insomeplantstheyadaptandstartstoringfood.
Flower isanother importantpart in theplant.Flowerhasdifferentcolourfulstructurescalledpetals.They attract insects for pollination and produce fruits.We grow plants for colourful flowers which givesbeautytonature.Wewilllearnmoreaboutflowerinthenextclasses.
Keywords:Tap root, fibrous roots, leaf, petiole, lamina, stomata, reticulate venation, parallel venation,transpiration
Whatwehavelearnt•Theimportantpartsofaplantareroots,stemandleaves.
•Taprootsystemandfibrousrootsystemaretwotypesofrootsystemsseeninplants.
•Rootsabsorbwaterandmineralsfromthesoilandalsohelpinanchoringtheplantbodytothesoil.
•Thestembearsbranches,leaves,flowersandfruits.
•Thestemcarriesthewaterabsorbedbytherootstodifferentpartsoftheplant.
•Leavesareinvolvedinpreparingfood.Theyalsohelpinexchangeofgasesandtranspiration.
•Leafbase,petioleandlaminaareallpartsofaleaf.
•Reticulateandparallelvenationarefoundinleaves.
Budsaresmallswellingsonaplantfromwhichashoot,leaf,orflowerusuallydevelops.
Improveyourlearning
1.Whataretheimportantpartsofaplant?
2.Howwillyoutellwhichpartofaplantisthestemandwhichistheroot?
3. Collect any plant from your surroundings. Draw its root structure.What can you say about its rootsystem?
4.Johnhasnoplaceinhishousebuthewantstoplantvegetablesliketomatoinhishouse.Suggesthimdifferentwaystodoso.
5.Whatwillhappenifaplantdoesn’thaveanyleaves?
6.Howdoesthestemhelptheplant?
7.Whattypeofvenationisfoundintheleavesofplantswithfibrousroots?
8.Iftheleaveshavereticulatevenationwhatwouldbethetypeofroot?
9.Explainthevariouspartsofaplantwiththehelpofadiagram.
10.Explainthepartsofaleafwiththehelpofadiagram.
11.Howcanyoushowthatplantsabsorbwaterthroughtheirroots?
12.Rajanisaid“Respirationtakesplaceinleaves”,isshecorrect?Howcanyousupportthisstatment.
13.Collecttheleavesofvariousplants.prepareaherbarium.Writeabriefreportontheirshapes,sizeandvenation.
14.Prepareagreetingcardwithdryleaves.
15.InActivity1yourteachersuggestednottoharmotherplantswhenyoucollectplantsforobservations.Whydidshesuggestso?
16Observeaplantwhichhashealthygreen leavesandbeautiful flowers.Writeyour feelingsabout theplantinyournotebook.
******
Grapesandclematishavestemsthatclimbwithtendrils,whichholdontoasurface,asthestemsgetlonger.