Scatteredthroughtheseasoftheworldarebillionsoftonsofsmallplantsandanimalscalledplankton.Mostoftheseplantsandanimalsaretoosmallforthehumaneyetosee.Theydriftaboutlazilywiththecurrents,providingabasicfoodformanylargeranimals.Planktonhasbeendescribedastheequivalentofthegrassesthatgrowonthedrylandcontinents,andthecomparisonisanappropriateone.Inpotentialfoodvaluehowever,planktonfaroutweighsthatofthelandgrasses.Onescientisthasestimatedthatwhilegrassesoftheworldproduceabout49billiontonsofvaluablecarbohydrateseachyear.Thesea’splanktongeneratesmorethantwiceasmuch.
Despiteitsenormousfoodpotential,littleeffortwasmadeuntilrecentlytofarmplanktonaswefarmgrassesonland.Nowmarinescientistshaveatlastbeguntostudythispossibility,especiallyasthesea’sresourcesloomevenmoreimportantasameansoffeedinganexpandingworldpopulation.
Nooneyethasseriouslysuggestedthat“planktonburgers”maysoonbecomepopulararoundtheworld.Asapossiblefarmedsupplementaryfoodsource,however,planktonisgainingconsiderableinterestamongmarinescientists.
Onetypeofplanktonthatseemstohavegreatharvestpossibilitiesisatinyshrimplikecreaturecalledkrill.Growingtotwoorthreeincheslong,krillprovidethemajorfoodforthegiantbluewhale,thelargestanimalevertoinhabittheEarth.Realizingthatthiswhalemaygrow100feetandweigh150tonsatmaturity,itisnotsurprisingthateachonedevoursmorethanonetonofkrilldaily.
Krillswimaboutjustbelowthesurfaceinhugeschoolssometimesmileswide,mainlyinthecoldAntarctic.Becauseoftheirpinkcolor,theyoftenappearasasolidreddishmasswhenviewedfromashiporfromtheair.Krillareveryhighinfoodvalue.Apoundofthesecrustaceanscontainsabout460calories—aboutthesameasshrimporlobster,towhichtheyarerelated.
Ifthekrillcanfeedsuchhugecreaturesaswhales,manyscientistsreason,theymustcertainlybecontendersasnewfoodsourceforhumans.
1.Whichofthefollowingbestportraystheorganizationofthepassage?
A.Theauthorpresentstheadvantagesanddisadvantagesofplanktonasafoodsource.
B.Theauthorquotespublicopiniontosupporttheargumentforfarmingplankton.
C.Theauthorclassifiesthedifferentfoodsourcesaccordingtoamountofcarbohydrate.
D.Theauthormakesageneralstatementaboutplanktonasafoodsourceandthenmovestoaspecificexample.
2.Accordingtothepassage,whyisplanktonregardedtobemorevaluablethanlandgrasses?
A.Itiseasiertocultivate.
B.Itproducesmorecarbohydrates.
C.Itdoesnotrequiresoil.
D.Itismorepalatable.
3.Whydoestheauthormention“planktonburgers”?
A.Todescribetheappearanceofonetypeofplankton.
B.Toillustratehowmuchplanktonawhaleconsumes.
C.Tosuggestplanktonasapossiblefoodsources.
D.Tocomparethefoodvaluesofbeefandplankton.
4.Whatismentionedasoneconspicuousfeatureofkrill?
A.Theyarethesmallestmarineanimals.
B.Theyarepinkincolor.
C.Theyaresimilarinsizetolobsters.
D.Theyhavegrasslikebodies.
5.Theauthormentionsallofthefollowingasreasonswhyplanktoncouldbeconsideredahumanfoodsourceexceptthatitis___.
A.highinfoodvalue.
B.inabundantsupplyintheoceans.
C.anappropriatefoodforotheranimals.
D.freeofchemicalsandpollutants.
更新时间:2024-11-24 04:58:56DBCBD
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Themotheralmost____whenshelearnedthathersonwasshotdead.
PartIVTranslation
Thecaptainrealizedthatthementriedtodeceivehimsohemadethemworkveryhardfortherestofthevoyage.(PassageOne)
Part IV Translation
By making vehicles lighter in weight aluminum has greatly reduced the amount of fuel needed to move them, (Passage Two)
According to the acoustics, continual exposure____ noise of high intensity would lead to loss of hearing.
Withoutregularsuppliesofsomehormonesourcapacitytobehavewouldbeseriouslyimpaired;withoutotherswewouldsoondie.Tinyamountsofsomehormonescanmodifymoodsandactions,ourinclinationtoeatordrink,ouraggressivenessorsubmissiveness,andourreproductiveandparentalbehavior.Andhormonesdomorethaninfluenceadultbehavior;earlyinlifetheyhelptodeterminethedevelopmentofbodilyformandmayevendetermineanindividual’sbehavioralcapacities.Laterinlifethechangingoutputsofsomeendocrineglandsandthebody’schangingsensitivitytosomehormonesareessentialaspectsofthephenomenaofaging.
Communicationwithinthebodyandtheconsequentintegrationofbehaviorwereconsideredtheexclusiveprovinceofthenervoussystemuptothebeginningofthepresentcentury.TheemergenceofendocrinologyasaseparatedisciplinecanprobablybetracedtotheexperimentsofBaylissandStarlingonthehormonesecretion.Thissubstanceissecretedfromcellsintheintestinalwallswhenfoodentersthestomach;ittravelsthroughthebloodstreamandstimulatesthepancreastoliberatepancreaticjuice,whichaidsindigestion.Byshowingthatspecialcellssecretchemicalagentsthatareconveyedbythebloodstreamandregulatedistanttargetorgansortissues.Baylissandstarlingdemonstratedthatchemicalintegrationcouldoccurwithoutparticipationofthenervoussystem.
Theterm“hormone”wasfirstusedwithreferencetosecretion.StarlingderivedthetermfromtheGreekhormone,meaning“toexciteorsetinmotion.Theterm“endocrine”wasintroducedshortlythereafter“Endocrine”isusedtorefertoglandsthatsecretproductsintothebloodstream.Theterm“endocrine”contrastswith“exocrine”,whichisappliedtoglandsthatsecrettheirproductsthoughductstothesiteofaction.Examplesofexocrineglandsarethetearglands,thesweatglands,andthepancreas,whichsecretspancreaticjuicethroughaductintotheintestine.Exocrineglandsarealsocalledductglands,whileendocrineglandsarecalledductless.
1.Whatistheauthor’smainpurposeinthepassage?
A.Toexplainthespecificfunctionsofvarioushormones.
B.Toprovidegeneralinformationabouthormones.
C.Toexplainhowtheterm“hormone”evolved.
D.Toreportonexperimentsinendocrinology.
2.Thepassagesupportswhichofthefollowingconclusions?
A.Thehumanbodyrequireslargeamountsofmosthormones.
B.Synthetichormonescanreplaceaperson’snaturalsupplyofhormonesifnecessary.
C.Thequantityofhormonesproducedandtheireffectsonthebodyarerelatedtoaperson’sage.
D.Theshortchildoftallparentsverylikelyhadahormonedeficiencyearlyinlife.
3.ItcanbeinferredfromthepassagethatbeforetheBaylissandStarlingexperiments,mostpeoplebelievedthatchemicalintegrationoccurredonly___.
A.duringsleep.
B.intheendocrineglands.
C.undercontrolofthenervoussystem.
D.duringstrenuousexercise.
4.Theword“liberate”couldbestbereplacedbywhichofthefollowing?
A.EmancipateB.DischargeC.SurrenderD.Save
5.Accordingtothepassageanothertermforexocrineglandsis___.
A.ductglands
B.endocrineglands
C.ductlessglands
D.intestinalglands.
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