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
58
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.
Which of the following terms refers primarily to mammals and birds?
选项
A、Warm-blooded.
B、Ectothermic.
C、Cold-blooded.
D、Poikilothermic
答案
A
解析
答案在第一和第二段里都能找到。
转载请注明原文地址:https://kaotiyun.com/show/CjU3777K
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
Imagineadiseasespreadingacrosstheglobe,killingmostlymiddle-agedpeopleorleavingthemchronicallydisabled.Thenoned
Cultureshockmightbecalledanoccupationaldiseaseofpeoplewhohavebeensuddenlytransplantedabroad.Likemostailments,
Cultureshockmightbecalledanoccupationaldiseaseofpeoplewhohavebeensuddenlytransplantedabroad.Likemostailments,
Peoplecanbeaddictedtodifferentthings—e.g.,alcohol,drugs,certainfoods,oreventelevision.Peoplewhohavesuchanad
Althoughspeechandwritingarethespecialmeansofcommunicatingofhumans,theinterchangealsotakesplaceinmanyotherway
Smokingmakesonesixtimesmorelikelytogetoralcancerpartlybecausethesmokeconstantlyassaultsthetissuesthatlineth
Childrenshouldavoidusingmobilephonesforallbutessentialcallsbecauseofpossiblehealtheffectsonyoungbrains.Thisi
Assoonasthebaby’sgoneoffwe’llbeabletorelaxandwatchtelevision.
Youngpeoplearevulnerabletotheinfluencesofradioandtelevision.
随机试题
女性,50岁,脐周隐痛、腹泻便稀或便秘交替近1年,无里急后重,无鲜血便。体格检查:腹部平软,未及肿块。血常规提示中度贫血。如怀疑患者患大肠癌,下列检查首选的是
青光眼滤过性手术后的并发症通常不包括
图示均质圆轮,质量为m,半径为r,在铅垂图面内绕通过圆轮中心O的水平轴以匀角速度w转动。则系统动量、对中心O的动量矩、动能的大小为:
每个防火分区相邻2个安全出口或每个房间疏散出口最近边缘之间的水平距离不应小于()m。
根据新股发行询价制度的规定,询价对象是指符合中国证监会规定条件的( )等。
下列关于直接人工标准成本制定及其差异分析的说法中,正确的有()。
在整个地图学史上,有效使用地图意味着看懂绘制在平面上的一系列抽象符号,然后将这些符号与当地环境的各种三维特征联系起来,从而成功地确定自己的位置。但这并不是所有普通人都能够做到的,而且不久之前,地图本身也还是一种稀缺的人工制品,有些地图还属于军事上敏感的机密
应用减数法进行证实的实验有()。
【B1】【B10】
WilltheWorldRememberDisneyorPlato?SignificantWorldwideInfluenceofAmericanCultureLONDON--Downinthemall,b
最新回复
(
0
)