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1、Unit4ExploringplantsPartTwo:TeachingResourcesSection2:BackgroundinformationforUnit4Exploringplants1.ImportanceofPlantsPlantsformthebasicfoodstapleforalllifeforms.Theyarethemajorsourceoffoodandoxygenonearth,sincenoanimalcansupplythesenecessarycomponentswithout
2、plants.Thecattleweeatasbeef,feedongrassesandthefishweeat,consumealgaeandarethereforedependentonplantsforwellbeing.Otherimportantusesofplantsinclude,providingshelterforanimals,providingmaterialsforclothing(cottonfibers),paperproducts,medicinesandotherchemicals
3、,producingcoalfromoncelivingplantmaterial,reducingwindspeedandnoiselevels,andreducingsoilerosionandwaterrunoff.Therearemanydifferenttypesofcashcropsthatproducemoneyforfarmers.Oliveoilcomesfromolives,cornoilcomesfromcorn,andpeanutoilcomesfrompeanuts.Typicalagr
4、iculturalproductslikecorn,wheat,rye,andriceareallconsideredcashcrops.Coffeeplantsproducebeansthatareusedtomakecoffee;cocaplantsgiveuschocolate;vanillaplantsgrowlongthinbeansthatareusedtoproducevanillaflavoring.Manydrinksandbeverages,likecolaandtea,comefrompla
5、nts.Rubberfromtreesisalsoacashcrop,asislumber,fruit,vegetables,andcotton.Plantsarealsousedinagriculturetohelpreducewindspeed.Plantingtreesinarowpreventsthewindfromblowingawaythevaluabletopsoil.Intheforest,treesactasshelterformanyorganisms.Plantsarealsoimporta
6、ntfortheoverallecologyofanarea.Rootshelptostabilizesoilandpreventerosionbywaterrunoff(soilconservation).Plantsarealsoimportantinouratmospherebecausetheyusecarbondioxideandgiveoffoxygenwhiletheyundergophotosynthesis.Plantsarealsousedintheurbansettingtoreduceno
7、ise,produceshade,andtobeautifyanarea.Treesaddvaluetohomesandcommunities.Plantsareessentialtothebalanceofnatureandinpeople'slives.Greenplants,i.e.,thosepossessingchlorophyll,manufacturetheirownfoodandgiveoffoxygenintheprocesscalledphotosynthesis,inwhichwateran
8、dcarbondioxidearecombinedbytheenergyoflight.Plantsaretheultimatesourceoffoodandmetabolicenergyfornearlyallanimals,whichcannotmanufacturetheirownfood.Besidesfoods(e.g.,grains,fruits,andveg
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