首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Studies of the Weddell seal in the laboratory have described the physiological mechanisms that allow the seal to cope with the e
Studies of the Weddell seal in the laboratory have described the physiological mechanisms that allow the seal to cope with the e
admin
2014-09-18
94
问题
Studies of the Weddell seal in the laboratory have described the physiological mechanisms that allow the seal to cope with the extreme oxygen depriva- tion that occurs during its longest dives, which can extend 500 meters below the ocean’ s surface and last for over 70 minutes. Recent field studies, however, suggest that during more typical dives in the wild, this seal’ s physiological behavior is different.
In the laboratory, when the seal dives below the surface of the water and stops breathing, its heart beats more slowly, requiring less oxygen, and its arteries become constricted, ensuring that the seal’ s blood remains concentrated near those organs most crucial to its ability to navigate underwater. The seal essentially shuts off the flow of blood to other organs, which either stop functioning until the seal surfaces or switch to an anaerobic(oxygen-independent)metabolism. The latter results in the production of large amounts of lactic acid which can adversely affect the PH of the seal’ s blood but since the anaerobic metabolism occurs only in those tissues which have been isolated from the seal’s blood supply, the lactic acid is released into the seal’ s blood only after the seal surfaces, when the lungs, liver, and other organs quickly clear the acid from the seal’s blood stream. Recent field studies, however, reveal that on dives in the wild, the seal usually heads directly for its prey and returns to the surface in less than twenty minutes. The absence of high levels of lactic acid in the seal’ s blood after such dives suggests that during them, the seal’ s organs do not resort to the anaerobic metabolism observed in the laboratory, but are supplied with oxy- gen from the blood. The seal’ s longer excursions underwater, during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laborato- ry. But why do the seal’ s laboratory dives always evoke this response, regardless of their length or depth? Some biologists speculate that because in laboratory dives the seal is forcibly sub- merged, it does not know how long it will remain underwater and so prepares for the worst.
Which of the following best summarizes the main point of the passage?
选项
A、Recent field studies have indicated that descriptions of the physiological behavior of the Weddell seal during laboratory dives are not applicable to its most typical dives in the wild.
B、The Weddell seal has developed a number of unique mechanisms that enable it to remain submerged at depths of up to 500 meters for up to 70 minutes.
C、The results of recent field studies have made it necessary for biologists to revise previous perceptions of how the Weddell seal behaves physiologically during its longest dives in the wild.
D、Biologists speculate that laboratory studies of the physiological behavior of seals during dives lasting more than twenty minutes would be more accurate if the seals were not forcibly submerged.
E、How the Weddell seal responds to oxygen deprivation during its longest dives appears to depend on whether the seal is searching for prey or avoiding predators during such dives.
答案
A
解析
主题类型:A.正确。最近野外研究指出:对于威德尔海豹在实验室中潜水时生理行为的描绘不适用于野外更典型的潜水。第一段的总结和其后全文的意思都是如此。B.威德尔海豹的独特机制使其能潜水500米深,70分钟长。显然,这是实验室研究内容,作者对此提出了不同意见。C.“during its longest dives”所说和原文不符,作者新研究成果是“most typical dives”。D.当海豹不被迫潜水,实验室结果会有效些。说反了。恰恰是被迫潜水时才和实验室中结果一样。E.此选项意思不通:最长时间潜水时海豹怎样对待缺氧问题取决于捕食还是逃跑。
转载请注明原文地址:https://kaotiyun.com/show/rctO777K
本试题收录于:
GMAT VERBAL题库GMAT分类
0
GMAT VERBAL
GMAT
相关试题推荐
Hespendsmoneylikewater.Infact,hisexpensesonfoodandclothesareratherhigh______hisincome.
WriteashortessayentitledFastFoodandTraditionalChineseCooking.Youshouldwriteatleast120wordsfollowingtheoutlin
Mr.WangteachesEnglishinamiddleschool.Helikeshisworkverymuch.Hewanted【C1】______ateacherevenwhenhewasayoung
Theperson______youweretalkingtowasanAmerican.
Gettingplentyofexerciseisveryimportant.Ienjoyswimmingverymuch.LastsummerIwenttothe【C1】______everyday.Iplant
Atthebeginningoflastcentury,medicalscientistsmadeaninterestingdiscovery:wearebuiltnotjustoffleshandbloodbut
Theydidnotfind______topreparefortheworstconditionstheymightmeet.
Someareas,______theirsevereweatherconditions,arehardlypopulated.
ToswimacrosstheEnglishChanneltakesatleastninehours.It’sahardworkanditmakesyoushortofbreath.Toflyoverthe
TheperformanceoftheEnglishteamwas________.Theyplayedmuchworsethanexpected.
随机试题
A.经尿道膀胱肿瘤切除术B.膀胱部分切除术C.全膀胱切除术D.根治性膀胱切除术E.膀胱切开肿瘤切除术膀胱侧壁、顶部、底部单个局限的浸润性肿瘤应选择的术式是
关于哺乳期避孕.正确的是
对水杨酸可进行哪些前体药物的结构修饰
信用公司债属于()
关于法与道德的共同点,下列哪些选项是正确的?()
金砖国家领导人第四次会晤于2012年3月28日在印度新德里举行,为了深入了解金砖五国经济社会发展的基本情况,根据国家统计局《金砖国家联合统计手册(2011)》;列表如下:金砖国家人均GDP(现价)最高的国家是()。
信息结构图是BSP对企业长期数据资源规划的图形表示,下述:Ⅰ.每一系统的范围Ⅱ.产生、控制和使用的数据Ⅲ.系统与系统间的关系Ⅳ.对给定过程的支持Ⅴ.系统间的数据共享结构图能勾画出的内容是
窗体上有一个名称为Textl的文本框,一个名称为Commandl的命令按钮。要求编写一个程序,统计文本框中0-9各数字字符的个数。某人编写如下程序:PrivateSubCommandlClick()Dimcount(10)As、Integer第
Language-basedlearningdisabilitiesareproblemswithage-appropriatereading,spelling,and/orwriting.Thisdisorderisnot
A、Sheisnotavailableuntiltheendofnextweek.B、Sheisnotareliablesourceofinformation.C、Shedoesnotliketakingexa
最新回复
(
0
)