【优化方案】高二英语（人教版必修8）单元过关检测（二）

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1、单元过关检测（二）（时间：120分钟，满分：150分）第I卷第一部分阅读理解「共两节，满分60分］第一节（共15小题；每小题3分，满分45分）阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。A（2014-长沙重点中学高三第四次月考）Whenyoulookatyourselfinthemirror,doyoueverwonderwhyyoulookthewayyoudo?Notwofaceslookexactlyalike,makingahumanfaceasuniqueasafingerprint.Genelics（遗传学）obviouslyplayamajor

2、role一notwofacessharethesameDNA.Buteveninidenticaltwins,therearestillsmalldifferencesintheirappearances.Sowhatisitthatmakeseachfacedifferent?TheanswerliesinasmallpieceofyourDNAcalleda“geneenhanceraccordingtoastudypublishedinScience.aTherearethousandsofenhancersinthehumangenome,"studyleaderAxelVi

3、sel,aresearcherwithBerkeleyLab.US.toldDiscovery.AccordingtoVisel,theseDNApiecesactlikeswitches,turninggenesonandoffandthereforedeterminingwhetheracertainfacialfeaturedevelopsinafetus（胎儿）whileitisstillinthewomb（子宫）•What，sinterestingaboutgeneenhancersisthattheydon"thavetobefoundanywhereclosetothe

4、genestheyaffect.Theyareabletocontroltheirtargetsfromfaraway,whichmakesthemevenmoreinfluential.TotesthowpowerfulthesespecialDNApiecesareinshapingtheface,researchersdeletedthreeofthegeneenhancersinmiceandcomparedthemwithnormalmiceat8weeksofage・Theresultsshowedthateachenhancerdeletioncausedadistin

5、ctsetofdifferencesintheshapeoftheface一forexample,causinganincreaseordecreaseinfaciallengthorwidth.Infact,scientistsfirstnoticedtheexistenceofgeneenhancerslongago,buttheycalledthem“junkDNA”backthenbecausetheydidn'tproduceproteinsandwerethoughttohavenobiologicalfunction.Butnowincreasinglycleartha

6、timportantfunctionsareembeddedinthisjunknViseltoldNewScientist.Understandingthismayhelpscientistslearnwhyandhowthingsgowrongasafetusdevelops,leadingtofacialbirthdefects（缺suchascleftlips.Maybegeneenhancersalsoplayarole.【语篇解读】为何每个人都长得不一样？文章介绍了科学家们研究基因对于人们长相的影响的实验，解释了这一个问题。1•WhatdidVisel'srecentst

7、udyuncover?A.Howgeneenhancershelpshapetheappearanceoftheface・B•Howgeneenhancersaffectthegrowthofthefetus.C.Anewcureforfacialbirthdefects.D・Theconnectionbetweengeneenhancersandgeneticmutations（变异）.解析：选A。主旨大意题。本文主要回答的是第二段提出的问题：Sowha