【高二 拓展阅读-自然】Why Leaves Change Colour

WhyLeavesChangeColour?Everyfall，youknowthedrill.Theleavesonthetreeschangecolourfromgreentoredorange，andyellow.Thetreesbecomeexplosionsofvibrantcolour.Eventually，theleavesturnbrownandfalloffthetrees.Ofcourseyouknowtheleaveschangecolourbeforewinter.Butdoyouknowwhy？Le’sstartwiththebasics，Treesneedtoeatanddrink，justlikeus.Buttheydon’teatfoodlikewedo.Instead，theleavesontreesusesunlighttoproducefood.Thisprocessiscalledphotosynthesis（光合作用）.Tha’squiteamouthfultosay！Le’stakeacloserlookathowphotosynthesisworks.Basically，thetreebreathesincarbondioxide，whichisintheairaroundus.Thetreetakesincarbondioxidefromporesonitsleaves.ThetreealsoabsorbswaterbyitsrootsEverytimeitrains，thetreeishappy！Theleavesaremadeupofverysmallcells，andinsidethosecellsaretinyformationscalledchloroplasts（叶绿体）.Eachchloroplasthasagreenchemicalthatgivesititscolour.Thatgreenchemicaliscalledchlorophyll.Thechlorophyllisveryimportantbecauseitallowsthephotosynthesistotakeplace.Whenthelightfromthesunenterstheleaf，thechlorophyllabsorbsthelightenergyThen，oxygenisreleasedfromtheleaves.Thatoxygengoesintotheairandhelpsusbreathe.Also，thelightenergyisturnedintosugarthatthetreesuseforfood.Thatsugariscalledglucose（葡萄糖）Nowle’sgetbacktowhyleaveschangecolour.Duringthespringandsummer，there'salotofsunlight.Butoncefallandwinterrollaround，itdoesn'tstaylightoutsideaslong.So，theleavesdon'tgetasmuchsunlightastheyusedto.Thechlorophyllintheleavesstartstodecrease.Andremember，chlorophyllgivesleavestheirgreencolour.Soifthereislesschlorophyll，theleaveslosetheirgreencolour.Sowheredotheothercolourscomefrom？Eventhoughleaveslooksolidgreentheyactuallyhavesmallamountsofothercoloursinthemtoo.Thechlorophyllisthemaincolourandisgreen.Thereisalso“carotenoid”（类胡萝卜素）whichmakesyellow，orangeandbrown.Andthereis“anthocyanin”（花青素）whichmakesredandpurple.Whenthegreenstartstofade，youcanstarttoseetheothercolourscomingout.Oncetheleafrunsoutoffood，itturnsbrown，dies，andeventuallyfallsoff.Everytreeisdifferent，sotheleaveschangecolourattheirownpace.Andthecoloursdependinthetemperature，theclouds，andtherain.Itisdifferenteveryfall.But，itisalwaysmagical.ReadingComprehensionChoosethecorrectanswerforeachquestion.1.Whichofthefollowingdoesaplantrequireforphotosynthesis?A.Carbondioxide.B.Water.C.Sunlight.D.Alloftheabove.2.Whichofthefollowingistheproductofphotosynthesisthatbenefitshumans?A.Oxygen.B.Glucose.C.Carbondioxide.D.Chlorophyll.3.Whatcanwelearnaboutglucosefromthisarticle?A.Itisasmallcellinleaves.B.Itisthesugarthatplantsuseforfood.C.Itisachemicalthatgivesleavestheirgreencolour.D.Itisachemicalthatmakesredandpurple.4.Wheredotheorange,yellow,browncoloursoffallenleavescomefrom?A.Chloroplast.B.Chlorophyll.C.Carotenoid.D.Anthocyanin.5.WhichstatementisNOTtrueaccordingtothearticle?A.Theleavesontreesusesunlighttoproducefood.B.Infallandwinter,thechlorophyllintheleavesincreases.C.Thetreeabsorbswaterbyitsroots.D.Thecoloursofleavesdependonthetemperature,theclouds,andtherain.Vocabulary基础词eventually adv.最后，终于英attheendofaperiodoftimeoraseriesofevents词根记忆：event（事件）+ual（有…性质的）+ly（…地）出事（之后）最后sunlight n.阳光，日光记组合词：sun（太阳）+light（光）→阳光搭outdoorsunlight户外的阳光produce vt.生产，制作；生长，出产；创作英togrowormakesthaspartofanaturalprocess记词根记忆：pro（向前）+duc（带来）+e→向前带出→生产例Theregionmainlyproduceswheat.这个地区主要生产小麦。breathe v.呼吸例Ican’tbreatheinthisroom.我在这个屋子里无法呼吸了。carbon n.碳搭carbondioxide二氧化碳dioxide n.二氧化物记词根记忆：di（二）+oxide（氧化物）→二氧化物cell n.细胞；小隔间；（蜂房的）巢室；电池搭cancercells癌细胞adrycell一节干电池actually adv.实际上；事实上；真实地记词根记忆：act（行动）+ual（…的）+ly（表副词）→实际行动地→实际上pace n.一步；速度；步调；节奏；进度ⅵ.缓慢而行，踱步记联想记忆：跳舞不是赛跑（race），要跟上节奏（pace）搭keeppacewith.跟上…（的步伐）depend v.依靠；依赖；取决于记词根记忆：de（表加强）+pend（悬挂）挂在…上面→依靠例Thecountrydependsheavilyonitsagriculture.这个国家在很大程度上依赖于农业。magical adj.魔术的；有魔力的；不可思议的；巫术的记来自magic（n.魔力）Vocabulary进阶词drill n.惯常的步骤，程序；钻（孔）；训练v.钻（孔），打眼；训练记联想记忆：dr（看作dry，干燥的）+ill（生病的）→生病了还坚持训练→训练例ThefirstoilwellwasdrilledbyEL.Drake，aretiredrailroadconductor.第一口油井是E.L.德雷克开凿的，此人是一名退休的铁路列车长。explosion n.爆炸；激增，急剧膨胀英thesuddenviolentburstingandloudnoiseofsthsuchasabombexplodingvibrant adj.明亮的，鲜艳的；活泼的，充满生气的；振动的英（ofcolours）verybrightandstrong记词根记忆：vibr（摇摆）+ant（…的）振动的；活泼的process n.过程；程序，手续；工序，制作法v.加工，处理记词根记忆：pro（向前）+cess(走）→向前走→过程例Thewomenusedtheirtoolstoprocessallofthefishandmarinemammalsbroughtinbythemen.女人用她们的工具加工男人带回来的所有的鱼和海洋哺乳动物。pore n.气孔，小孔ⅵ.仔细阅读，审阅；审视英averysmallholeintheskinofpe