韩苏2014考研英语阅读每日一篇.docx

韩苏2014考研英语阅读每日一篇.docx

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1、韩苏:2014考研英语阅读每日一篇(36) 2014考研基础阅读每日一篇第三十六篇如约而至,呵呵,只要努力,就能成功,锲而不舍,金石可镂!我们一起做起来吧!  Unit7科学世界  Text6正文  Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombined.C.R.Darneshassuggestedthatitisaspropertotermtheplantawaterstructureastocallahousecomposedmainlyofbrick--

2、abrickbuilding.Certainitisthatallessentialprocessesofplantgrowthanddevelopmentoccurinwater.Themineralelementsfromthesoilthatareusablebytheplantmustbedissolvedinthesoilsolutionbeforetheycanbetakenintotheroot.Theyarecarriedtoallpartsofthegrowingplantandarebuiltintoessentia

3、lplantmaterialswhileinadissolvedstate.Thecarbondioxidefromtheairmayentertheleafasagasbutisdissolvedinwaterintheleafbeforeitiscombinedwithapartofthewatertoformsimplesugars--thebasematerialfromwhichtheplantbodyismainlybuilt.Activelygrowingplantpartsaregenerally75to90percen

4、twater.Structuralpartsofplants,suchaswoodystemsnolongeractivelygrowing,mayhavemuchlesswaterthangrowingtissues.  Theactualamountofwaterintheplantatanyonetime,however,isonlyaverysmallpartofwhatpassesthroughitduringitsdevelopment.Theprocessesofphotosynthesis,bywhichcarbondi

5、oxideandwaterarecombined--inthepresenceofchlorophyll(叶绿素)andwithenergyderivedfromlight--toformsugars,requirethatcarbondioxidefromtheairentertheplant.Thisoccursmainlyintheleaves.Theleafsurfaceisnotsolidbutcontainsgreatnumbersofminuteopenings,throughwhichthecarbondioxideen

6、ters.Thesamestructurethatpermitstheonegastoentertheleaf,however,permitsanothergas--watervapor--tobelostfromit.Sincecarbondioxideispresentintheaironlyintracequantities(3to4partsin10,000partsofair)andwatervaporisnearsaturationintheairspaceswithintheleaf(at80F,saturatedairw

7、ouldcontainabout186partsofwatervaporin10,000partsofair),thetotalamountofwatervaporlostismanytimesthecarbondioxideintake.Actually,becauseofwindandotherfactors,thelossofwaterinproportiontocarbondioxideintakemaybeevengreaterthantherelativeconcentrationsofthetwogases.Also,no

8、tallofthecarbondioxidethatenterstheleafissynthesizedintocarbohydrates(碳水化合物).  Text6习题  1.Agrowingplant

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