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阅读原文+译文+题目+答案+背景知识TPO65The PitOrgans ofSnakes原文The PitOrgans ofSnakes
①It is thought that the facial pits or pit organs on the head of some snakes arespecialized infrared heat receptors.When a rattlesnake strikes,the directionof thestrikeseems to be guided by the infrared radiation from its prey.A rattlesnake strikesonly at warm-blooded prey,and whenthe preyis deadand at room temperature,thesnake will not strike.However,a blindfolded snake strikescorrectly at a deadrat thatis pulled across the cage,provided therat is warmer thanthe surroundings.Blindfolded,the snakecannot be guided byvision;nor isit guidedby the sense ofsmell,for itwill strikecorrectly evenat amoving,cloth-wrapped electricbulb.The pitorgans are evidently involved in sensing the location of warm objects.All snakesthathave pit organs feedpreferentially onwarm-blooded prey,and thisfurther supportstheview that these organsare infraredsensors.In therattlesnake the pit organsarelocated,one oneach side,between thenostril and the eye;they areconnected tomanynerves,and this in itselfsuggests asensory rolefor theorgan.
②The sensitivityof the facial pithas beenexamined byrecording the activity in thenerve leadingfrom theorgan.A variety of stimuli,such assound,vibration,or lightofmoderate intensitywith theinfrared part of thespectrum filteredout,has nodetectable effect on the activity in thenerve.However,if objectsof atemperaturedifferent from the surroundingsare broughtinto the receptive field around the head,there is a strikingchange in nerve activity,regardless of the temperatureof theinterveningair.
③How istheinfrared radiation sensedThe pitis coveredby athin transparentmembrane,and ithas beensuggested that a risein temperature in the pit behindthemembrane couldcause anexpansion of the gaswith aconsequent deformationof themembrane.This inturn couldbe sensedby asuitable receptor.This hypothesisishighly improbable,for acut in the membranethat opensthe pitto theoutside aircausesno lossin responsiveness,a resultthat isincompatible、牙齿2牙齿不管蛇有没有毒,它们毫无疑问都拥有牙齿,而且都可能会用牙齿伤害我们但是,它们的牙齿也是存在一些差异的毒蛇的牙齿需要将毒液注入猎物体内,而毒液是在位于眼睛上方的腺体中产生的,因此你可以观察到这个部分而无毒蛇则比较难以发现有毒蛇那样明显的“牙龈”和尖牙它们的尖牙可能会更小且不那么明显它们通常会依靠这些牙齿来防止猎物逃脱,以便于将它们吞到肚子里、咬过的伤口3咬过的像口不管是毒蛇还是无毒蛇,只要是被蛇咬伤就一定要尽快接受正规的医疗救助但是,如果你能识别蛇是否有毒会更好,因为被有毒蛇咬伤需要更快接受治疗很明显的是,被毒蛇咬伤的伤口处可以看到明显的个刺痕,它们来自两颗毒牙而无毒蛇2则只会留下两排牙齿的痕迹有毒蛇的伤口往往会出现肿胀、瘀伤和疼痛,而无毒蛇则会出现肿胀、发红、瘙痒甚至出血、头和瞳孔4桶!)关头和隆孔从蛇的头部和瞳孔也能够大致判断它们是否有毒,因为大部分毒蛇的头部都呈三角形的形状,瞳孔和猫的有点相似,都是垂直椭圆形状正常情况下,无毒蛇的瞳孔是圆形的,头部是椭圆形的但是,需要注意的是,有一些毒蛇的瞳孔也是圆形的,它们会根据光线而产生变化在光线暗的时候,就会变得更圆此外,像珊瑚蛇这样的危险毒蛇,瞳孔就是圆形的但大多数情况,三角形的头部和椭圆瞳孔符合大部分的毒蛇特征、行为5毒蛇和无毒蛇的行为也是存在不同的当然,不管是否有毒,正常它们会远离人类,或保持静止不让我们发现一些毒蛇拥有独特的行为,例如响尾蛇,它们的尾巴会施桁的瞳孔发出很容易识别出来的嘎嘎声它们通过这种方式来警告捕食者一些毒水蛇会全身浮出游泳,而大部分无毒蛇只会将头浮出水面、凹陷器官6凹陷器官蛇的头部拥有凹陷器官,这种器官是用来探测温血猎物的,呈小孔状事实上,通常情况下,只有毒蛇才会在鼻子和眼睛中拥有凹陷器官但也有少数无毒蛇也拥有凹陷器官,例如某些蟒蛇、拟态蛇7有一些无毒蛇拥有模仿毒蛇外观和色彩的能力,通过模仿的方式,它们或许能够获得类似的图案和颜色,让其它捕食者不敢接触它们但值得注意的是,模仿的外观依然是存在区别的例如,猩红蛇会模仿珊瑚蛇的外观,因此也被称为假珊瑚蛇猩红蛇有相互接触的红色和黑色带,但珊瑚蛇是红色和黄色相互接触的,而不是红色和黑色,而且颜色会更加鲜艳、“眉头紧锁”的形态8“眉头紧锁”的形态追关肾锁”元“盾关肾锁”,1虽然我们知道蛇没有人类这样丰富的面部肌肉,更不会做出眉头紧锁的表情然而,有一些蛇的眼睛附近拥有鳞片会让它们看起来像眉毛一样像响尾蛇、水腹蛇这样的毒蛇都拥有类似于“眉头紧锁”的形态with thehypothesis thata pressurechange issensed.
④We areleft withtwo otherpossibilities toconsider:Either theeffect isphotochemical,which meansthat theinfrared radiationis absorbedby aspecificcompound,analogous to the light-sensitive pigmentsin the eye,or the pit organsaresensitive to the slighttemperature risecaused wheninfrared radiationreaches it.Theinfrared radiationemitted froma mammalianbody haslow quantumenergy,whichmakes anyphotochemical effect on apigment extremelyunlikely.Pure infraredradiationcan beproduced by a laser,and experimentswith suchradiation ofknownwavelength providestrong evidencethat themode ofreception in the facial pit organisentirely thermal.
⑤Can the pit organsbe used for perceptionof theinfrared sourcein theway ourtwoeyes areusedforstereoscopic visionThis seemslikely,not onlyfrom observationsofthe precisionwith whicha snakecan strike,but alsofrom studiesof itsbrain activity.When infrared radiation fallson thefacial pitorgan,electric activitycan berecordedfrom the optic tectum,the part of the brain with which the optic nerveis connected.This in itself issuggestive;although the nerves from the pitorgan arecompletelyseparate from the optic nerves,the samepartof the brainseems tohandle visualinformation,which isknown tobe stereoscopic,and infraredinformation.The optictectumhas left and rightparts,located oneither side of thebrain.Each partreceivesinput fromeach eyevia theoptic chiasma,the pointat whichtheoptic nerves fromtheleftandright eyemeet.Many of the neuronsin thetectum respondto stimulationof thepitorgan on the oppositeside of thehead.This isreminiscent of the wayinformationfrom theeyes ishandled;the crossoverof theopticnervein theopticchiasma isessential forstereoscopic visionand interpretationof distance.Informationfrom the two pit organs isapparently coordinatedand interpretedin asimilar way,aconclusion in agreement withrecorded changesin theneural activityin thetectumwhen theinfrared sourceisina positionto irradiateboth pitsat once.It thereforeappears that thefacial pits indeed provide stereoscopic perceptionand substantiallyaid in the precision of estimating the location of prey.译文蛇的坑状器官
①据认为,一些蛇面部的凹陷或头部的凹陷器官是特殊的红外(热)感受器响尾蛇攻击时,攻击的方向似乎是受猎物发出的红外辐射引导的响尾蛇只攻击温血动物,当猎物死亡且处于室温时,响尾蛇不会攻击它然而,一条蒙着眼睛的蛇会准确地攻击一只被拉过笼子的死老鼠,前提是老鼠的温度高于周围环境被蒙住眼睛,蛇既不受视觉引导也不受嗅觉的引导,因为它甚至能准确击中一个移动的、裹着布的电灯泡凹陷器官明显参与了对温暖物体的定位所有有凹陷器官的蛇都优先捕食温血动物,这进一步支持了这些器官是红外传感器这个观点响尾蛇的凹陷器官位于鼻孔和眼睛之间,两侧各有一个;它们与许多神经相连,这本身就暗示了该器官的感觉作用
②面部凹陷的敏感性已通过记录由器官发起的神经传导活动来验证各种各样的刺激,如声音、振动或中等强度的光(光谱的红外部分被过滤掉),对神经活动没有可检测到的影响然而,如果把温度与周围环境不同的物体带到头部周围的感受区,不管中间空气的温度如何,神经活动都会发生显著的变化
③红外线辐射是如何被感知的?凹陷表面覆盖着一层透明的薄膜,有人认为膜后凹陷温度的升高会导致气体的膨胀,从而导致膜的变形这反过来又能被合适的受体感觉到这一假设可能性极其低,因为在膜上的一个切口打开凹陷,使其与外界空气接触,并不会导致反应性的丧失,这一结果与压力变化被感知的假设是不一致的
④还有两个可能性可以考虑:一个是光化学效应,这意味着红外辐射被特定化合物吸收,类似于眼睛中的感光色素,另一个是当红外线到达凹陷器官,温度会轻微上升,这种上升凹陷器官会感知到哺乳动物身体发出的红外辐射具有较低的量子能量,这使得对色素产生光化学效应的可能性极小激光可以产生纯红外辐射,这种已知波长辐射的实验提供了强有力的证据,表明面部凹坑器官的接收模式完全是热的
⑤凹陷器官能像我们的双眼感知立体视觉一样,被用来感知红外线释放源吗这似乎是有可能的,不仅从对蛇攻击精度的观察来看,而且从对其大脑活动的研究来看当红外辐射落在面部凹陷器官上时,大脑中连接视神经的视神经顶盖部就可以记录下神经电活动这本身就很有启发性;虽然来自凹陷器官的神经与视神经完全分离,但大脑的同一部分似乎处理视觉信息(即已知的立体)和红外信息视神经顶盖分为左右两部分,分别位于大脑的两侧每一部分通过视交叉点接收来自每只眼睛的信息,视交叉点是左眼和右眼的视神经交汇的地方顶盖上的许多神经元会对头部另一侧凹陷器官的刺激作出反应这让人想起眼睛处理信息的方式;视交叉中视神经的交叉对立体视觉和距离的解释是必不可少的来自两个凹陷器官的信息显然是协调的,并以相似的方式解释,这一结论与红外源同时照射两个凹陷时所记录的顶盖神经活动的变化一致因此,面部凹陷确实提供了立体感知,并在很大程度上有助于精确地估计猎物的位置题目
1.According toparagraph1,arattlesnakewill onlystrike atprey whenA.the snakeis able to seethe preyB.the preyemits chemicalodorsC.the preyis movingD.the preyiswarmer than itssurroundings
2.Why doesthe authormention aucloth-wrapped electricbulb“in the passageA.To illustratethe sizeof preyusually attackedby snakesB.To provethat blindfolded snakes will strike moreoften ata deadrat thanan electricbulbC.To eliminatethe possibilitythat snakeslocate preyby usinga senseof smellD.To explainhow scientistswere ableto trickblindfoldedsnakes
3.Which ofthe sentencesbelow bestexpresses theessential informationin thehighlightedsentence in the passageIncorrect choiceschange themeaning inimportantways orleave outessential information.A.However,if objectsin thesurrounding areaexperience atemperature change,nerve activitycauses achange in temperaturein the receptive field around the snakes head.B.When objectsthat differintemperaturefromthe surroundings enterthe receptivefieldaround thehead,the resultisadramatic change innerve activity.C.Nerve activitychanges whennew objectsare introducedinto thearea aroundasnake shead,regardless ofhow theirtemperature comparesto thatof thesurroundingair.D.The temperatureoftheair in thereceptivefieldaroundthe snakesheadhas aneffectonthenerve activityofthe snake ifthe objectsin thefield areatadifferenttemperature.
②The sensitivityofthefacialpithas beenexamined byrecording theactivityinthenerve leadingfromtheorgan.A varietyof stimuli,such assound,vibration,or lightofmoderate intensitywith theinfrared partofthespectrum filteredout,has nodetectableeffectontheactivityinthenerve.However,if objectsof atemperaturedifferent fromthe surroundingsare broughtinto thereceptivefieldaroundthehead,there isa strikingchangeinnerveactivity,regardless ofthe temperatureof theinterveningair.
4.The word“consequent“inthe passage isclosest inmeaning toA.resultantB.eventualC.prematureD.visible
5.Which ofthe followingcan beinferred fromthe discussionabout infraredsensationand pit organs inparagraph3A.Rattlesnakes havespecial receptorsthat detectpressure changesinthepit organmembrane.B.Damaged pitorgan membranesdo notprevent arattlesnake fromdetecting awarmanimal nearby.C.The experimentson pitorgan membraneswere conductedinachamber withair atoutsidetemperatures.D.The idea that pit organs helpsnakes to locate preyby radiationhas beendisproved.
6.According toparagraph4,which ofthe followingtends toexclude aphotochemicalexplanation for the sensoryfunction ofsnake pit organsA.Only laserscan producethe exactwavelengths ofradiation that have an effect onpit organs.B.Light-sensitive pigmentsare locatedintheeyes butnot inthepitorgans ofsnakes.C.Compounds sensitive to infraredradiation havenot yetbeen identifiedin snakepitorgans.D.The infraredradiationfroma snake,spreyhas toolittle energyto affectthe snakespigments.
7.The word“substantially“inthe passage isclosest inmeaning toA.reliablyB.undoubtedlyC.frequentlyD.significantly
8.According toparagraph5,all ofthe followingsupport theideathata snakeuses itspitorgans forstereoscopic perceptionEXCEPT thefact thatA.stimulation ofa pitorgan hasaneffectonthetectum onthe oppositesideofthebrainB.the samepartofthebrainthat dealswith stereoscopicvision isactivated byinfraredstimulation ofthepitorgansC.thenervesoftheright eyeand theright pitorgan arecompletely separatefrom thenervesoftheleft eyeandtheleft pitorganD.a snakeis ableto strikeits preywith precision
9.Look atthe foursquares[H]that indicatewhere thefollowing sentencecould beaddedtothe passage.Where wouldthe sentencebest fitClick ona square[H]to addthesentence tothe passage.Infrared radiationcan beperceived directlybyafew animalsthathavespecializedsense organsthat respondto thistype ofradiation..
①isthoughtthatthefacial pitsorpitorgansontheheadofsomesnakes arespecializedinfraredheatreceptors.[・]When arattlesnake strikes,the directionof thestrikeseems tobeguidedby theinfraredradiationfrom itsprey.[H]A rattlesnakestrikesonly atwarm-blooded prey,and whenthe preyis deadand atroomtemperature,the snakewillnotstrike.[■]However a blindfoldedsnakestrikes/correctly ata deadrat thatis pulledacross thecage,provided therat iswarmer thanthesurroundings.Blindfolded,thesnakecannot beguidedbyvision;nor isit guidedby川thesenseof smell,for itw strikecorrectly evenatamoving,cloth-wrapped electricbulb.The pitorgansareevidentlyinvolvedinsensingthelocationofwarmobjects.Allsnakes thathave pitorgans feedpreferentially onwarm-blooded prey,and thisfurthersupports theview thatthese organsare infraredsensors.In therattlesnake thepitorgans arelocated,one oneach side,between thenostril andtheeye;they areconnectedto manynerves,and thisinitselfsuggests asensory rolefor theorgan.
10.Directions:An introductorysentence fora briefsummary ofthepassageisprovided below.Complete thesummary byselecting theTHREE answer choices thatexpressthe mostimportant ideas inthepassage.Some sentencesdo notbelong inthesummary becausethey expressideas thatare notpresented inthepassageor areminorideasinthepassage.Drag youranswerchoicestothespaces wherethey belong.To removean answerchoice,click onit.To reviewthepassage,click VIEWTEXTStudies indicatethatthefacialpitorgans ofcertain snakesare infraredsensors.A.Some snakes seem tobe abletolocateand strike atwarm-blooded preysolelythrough theuse ofpitorgans.11The pitorgans ofsnakesseem tobe sensitiveto a varietyof stimuli,including sound,vibration,and light,as wellas heat.C.The precisionwithwhichsnakesareabletolocate preycan beaccounted forby theintersection oftheopticnerves and nerves fromthepitorgans.D.Snakes with pitorgans willstrikeat dead rats atroom temperatureonly whentherats aredragged acrossa cage.E.Experiments providestrong evidencethat snakepitorgansare sensitivetotemperature changescaused byinfraredradiation.F.Studies ofbrain activitysuggest thatthetwofacial pitsprovide snakeswithstereoscopic perceptionfortheexact locationofprey.答案1-
5.DCB AB6-
9.DDCA
10.AEF小结题解析正确,符合第一段中讲述的内容,可以仅仅用去定位并攻击A snakepit organswarm-blooded preyoB错误,第二段第二句中指出‘Avariety ofstimuli,such assound,vibration,or lightof,即moderate intensityhas nodetectableeffectpitorgansseemtobesensitivetoa与原文表述相反;varietyofstimuli错误,这点在文C theintersectionoftheopticnervesandnervesfromthepitorgans中未提及错误,这点错D Snakeswithpitorganswillstrikeatdeadratsatroomtemperature了,第一段中提到ablindfoldedsnakestrikescorrectly ata deadrat thatispulled攻击的acrossthecage,provided therat iswarmerthanthesurroundings.Snake dead是比周围温度要高的rat正确,第二段和第四段的最后一句中提到了证据,且表明了E snakepitorgansaresensitive totemperature changescaused byinfrared radiationo正确,符合文章最后一段讨论的内容,且直接对应到最后一段最后一句的结论F Itthereforeappearsthatthefacialpitsindeedprovidestereoscopicperception andsubstantiallyaidintheprecisionofestimatingthelocationof preyo背景知识实用冷知识如何判断蛇是否有毒?这里有个小技巧8没有人会想要碰到蛇,可以说大部分的人其实是害怕蛇的很多人会尽可能远离蛇,这么做是对的,因为有不少蛇是有毒的,被它们咬上一口可能出现致命危险而且,大多数的人根本就无法区别蛇是否有毒了解这个知识其实是很有用的,尤其是当你发现有人被蛇咬伤时,可以更快的做出决定这一次,小编带来了,判断蛇是否有毒的个小知识
8、颜色和图案1颜色和图案虽然不完全准确,但通过颜色和图案,你可以大致的识别出一些毒蛇例如珊瑚蛇这样的剧毒蛇,它们往往拥有黑色、红色和黄色条纹的彩色图案科学家们相信,不少毒蛇拥有鲜艳的色彩是因为它们以明亮的颜色来警示其它捕食者不要靠近危险的自己有趣的是,有一些无毒蛇可以模仿颜色,通过模仿鲜艳的色彩来避免受到伤害一些有毒的铜头蛇的身上拥有非常独特的沙漏形图案。