2017考研英语理学类阅读理解模拟题及答案(二).docx

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1、优选2017考研英语理学类阅读理解模拟题及答案（二）Ithaslongbeenknownthattherateofoxidativemetabolism(theprocessthatusesoxygentoconvertfoodintoenergy)inanyanimalhasaprofoundeffectonitslivingpatterns.Thehighmetabolicrateofsmallanimals，forexample，givesthemsustainedpowerandactivityperunitofweight，b

2、utatthecostofrequiringconstantconsumptionoffoodandwater.Verylargeanimals，withtheirrelativelylowmetabolicrates，cansurvivewellonasporadicfoodsupply，butcangeneratelittlemetabolicenergypergramofbodyweight.Ifonlyoxidativemetabolicrateisconsidered，there-fore，onemightassumethat

3、smaller，moreactive，animalscouldpreyonlargerones，atleastiftheyattackedingroups.Perhapstheycouldifitwerenotforanaerobicglycolysis，thegreatequalizer.Anaerobicglcolysisisaprocessinwhichenergyisproduced，withoutoxygen，throughthebreakdownofmuscleglycogenintolacticacidandadenosi

4、netri-phosphate(ATP)，theenergyprovider.Theamountofenergythatcanbeproducedanaerobicallyisafunctionoftheamountofglycogenpresent-inallvertebratesabout0.5percentoftheirmuscles'wetweight.Thustheanaerobicenergyreservesofavertebrateareproportionaltothesizeoftheanimal.If，forexam

5、ple，somepredatorshadattackeda100-tondinosaur，normallytorpid，thedinosaurwouldhavebeenabletogeneratealmostinstantaneously，viaanaerobicglycolysis，theenergyof3，000humansatmaximumoxidative8/8优选metabolicenergyproduction.Thisexplainshowmanylargespecieshavemanagedtopetewiththeir

6、moreactiveneighbors：thepensationforalowoxidativemetabolicrateisglycolysis.Therearelimitations，however，tothispensation.Theglycogenreservesofanyanimalaregood，atmost，foronlyabouttwominutesatmaximumeffort，afterwhichonlythenormaloxidativemetabolicsourceofenergyremains.Withthe

7、conclusionofaburstofactivity，thelacticacidlevelishighinthebodyfluids，leavingthelargeanimalvulnerabletoattackuntiltheacidisreconverted，viaoxidativemetabolism，bytheliverintoglucose，whichisthensent(inpart)backtothemusclesforglycogenresynthesis.Duringthisprocesstheenormousen

8、ergydebtthattheanimalhasrunupthroughanaerobicglycolysismustberepaid，adebtthatisproportionallymuchgreate