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
医学
Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective funct
Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective funct
admin
2013-12-06
34
问题
Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37°C; a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations, the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature.
For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperatures. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into "warm-blooded’ and "cold-blooded" species; warm-blooded included mammals and birds, whereas all other creatures were considered cold-blooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana—each cold-blooded—usually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called homotherms, and those whose body temperature varies with their environment, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience a change in the chill of the deep water, and their body temperatures remain constant.
The current distinction is between animals whose body temperature is regulated chiefly by internal metabolic processes and those whose temperature is regulated by, and who get most of their heat from, the environment. The former are called endotherms, and the latter are called ectotherms. Most ectotherms do regulate their body temperature, and they do so mainly by locomoting to favorable sites or by changing their exposure to external sources of heat. Endotherms(mainly mammals and birds)also regulate their temperature by choosing favorable environments, but primarily they regulate their temperatures by making a variety of internal adjustments.
According to the passage, the chief way in which ectotherms regulate their temperature is by_____.
选项
A、seeking out appropriate locations
B、hibernating part of the year
C、staying in deep water
D、triggering certain metabolic processes
答案
A
解析
答案见第三段第三句:they do so mainly by locomoting to favorable sites or by changingtheir exposure to external sources of heat,显然答案是A。其余选项与问题相去甚远。
转载请注明原文地址:https://kaotiyun.com/show/xjU3777K
本试题收录于:
医学博士外语题库考研分类
0
医学博士外语
考研
相关试题推荐
Cultureshockmightbecalledanoccupationaldiseaseofpeoplewhohavebeensuddenlytransplantedabroad.Likemostailments,
Englishspeakerspickuppitchintherighthemispheresoftheirbrains,butspeakersofcertainotherlanguagesperceiveiton
A、Sheisonthewrongfloor.B、Shedoesnotknowanynurse.C、Shecannotfindtheimmunizationarea.D、Shereceivedanimmunizat
Certaindrugscancausetransientsideeffects,suchassleepiness.
A、Evenprimitivelifeisimpossible.B、Intelligentlifeisfairlycommon.C、Intelligentlifeislesslikely.D、Anyformoflife
Womenfindamasculineface—withalargejawandaprominentbrow—-moreattractivewhentheyaremostlikelytoattractive,acco
A、Turnonthetelevision.B、Changethechannelimmediatelyforthewoman.C、Continuewatchingthenatureprogram.D、Checktosee
Recentlyanumberofcaseshavebeenreportedofyoungchildren______aviolentactpreviouslyseenontelevision.
A、She’dliketowatchtelevisionwiththeman.B、Themanshouldn’twastehistimewatchingtelevision.C、Themanshouldwashdis
随机试题
在PowerPoint2010中,在空白幻灯片中不可以直接插入()
下列哪一项未列在《食品卫生法》第26条"不得参加接触直接入口食品的工作"所患疾病
下列哪项不是得神的表现
登记账簿要用蓝黑墨水或者碳素墨水书写,不得使用圆珠笔(银行的复写账簿除外)或者铅笔书写。()
下列关于权责发生制的表述中,不正确的是()。
如图所示,有一束平行于等边三棱镜截面ABC的单色光从空气射向E点,并偏折到F点。已知入射方向与边AB的夹角为0=-30°,E、F分别为边AB、BC的中点,则()。
下列哪个阶段,学生的伦理道德开始形成但又具有两极分化的特点?()
教师在对教具和实验进行演示操作的同时,最重要的是必须()。
文中“人们也称其为河外星云”的“其”字指代的是:根据文意,直接形成太阳系的是:
设A,B为n阶矩阵,则下列结论正确的是().
最新回复
(
0
)