TOEFL READING 1994/05(3)
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 37æ;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 temperature. 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 homeotherms, 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 best from, the environment. The former
are called endothermic , and the latter mainly by locomotion so favorable sites
or by changing their body temperature , and they do so mainly by decimating to
favorable sites or by changing their exposure to external sources of hear .
Enstotherms (mainly mammals ,and birds )also regulate their temperature by
choosing favorable environments , but primarily they regulate their temperature
by making a variety of internal adjustments.
重点单词：
cell : n. 单元,细胞,电池
remain : vi. 保持,逗留,剩余
alive : a. 活着的,活泼的,敏感的,热闹的
limit : n. 界限,边界,限度,极限,限制;vt. 限制,限定,减少
narrow : n. 狭窄部分,海峡,隘路;a. 狭窄的,精密的,有限的,气量小的,勉强的,眼光短浅的;vi.
变窄;vt.
使变狭窄
mark : n. 标志,分数,马克,戳记,印象,痕迹,刻度,靶子,目标,符号,标准,花押,特征,起跑线,记号,名声,
斑点;vt. 做标记于,留意,打分数,标志,表明,记录;vi. 作记号,记得分
boundary : n. 边界,分界线
effective : a. 有效的,有力的,实际的;n. 有生力量
enzyme : n. 酶
departure : n. 离开,出发,违背,偏离,发射
value : n. 价值,重要性,价格,估价,计算结果,评价,购买力;vt.
评价,估价,重视
serious : a. 严肃的,认真的,重要的,严重的
impair : vt. 损害,减少,削弱
survive : vt. 生存,生还,幸免于;vi. 活下来,幸存
fluctuation : n. 变动,上下,动摇
integrated : a. 综合的,完整的
tolerance : n. 容许量,公差,宽容,忍受,容忍
differ : vi. 不一致,不同
regulate : vt. 系统地管理,规定,调节,调整,使整齐
characterize : vt. 表示...的特色,赋予特色
accurate : a. 正确的,精确的
meaningful : a. 意味深长的
terminology : n. 用辞,术语学
still : n. 蒸馏室,寂静,剧照;vt. vi. 蒸馏,(使)平静,(使)静止;a.
静止的,不动的,静寂的,不起泡的,静物摄影的;ad. 仍然,更,静止地;conj.
然而,但是;静止画面,静态图片
reflect : vt. 反射,反映,招致,想到,归咎,思考;vi. 反射,映出,思考,考虑,指责,怀疑
division : n. 区分,除法,公司,师,分开
whereas : conj. 然而,反之,鉴于
evident : a. 显然的,明显的
classification : n. 分类,分级
inadequate : a. 不充分的,不适当的
fence : n. 围墙,栅栏,剑术;vt. 用篱笆围住,练习剑术,防护;vi.
击剑,搪塞
lizard : n. 蜥蜴
iguana : n. 鬣蜥
distinction : n. 区别
maintain : vt. 维持,维修,保持,坚持,供养,主张
constant : n. 常数,恒量;a. 不变的,一定的,时常的
homeotherm : n. 恒温动物
environment : n. 环境,外界,围绕
poikilotherm : 变温动物
prove : vt. 证明,查验,检验,勘探,显示;vi. 证明是
hibernation : n. 过冬,冬眠,避寒
furthermore : ad. 此外,而且
invertebrate : a. 无脊骨的,无脊椎的,无骨气的;n. 无脊椎动物,无骨气的人
experience : n. vt. 经验,体验
chiefly : ad. 主要地
metabolic : a. 变化的,变形的,新陈代谢的
endothermic : n. 吸热
locomotion : n. 运动,移动,转位
favorable : a. 有利的,赞许的,良好的
decimate : vt. 每十人杀一人,大批杀害
exposure : n. 暴露,揭发,揭露
choose : vt. 选择,宁愿,欲;vi. 选择,喜欢
primarily : ad. 主要地,首先地,基本地
adjustment : n. 调整,调节,校正
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