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.

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Grapesandclematishavestemsthatclimbwithtendrils,whichholdontoasurface,asthestemsgetlonger.