1、E1 温度与代谢要 点恒温动物和变温动物按照有机体的体温调节过程有可能对有机体进行分类。一种可能的划分是恒温动物和变温动物。当环境温度升高时，恒温动物保持着大致恒定的体温，而变温动物的体温随环境温度而改变。这种分类的一个问题是，即使是典型的恒温动物也经历了降低体温的时期。在有机体之间，可供选择的另一种划分描述如下。恒温动物变温动物E1 TEMPERATURE AND METABOLISMIt is possible to categorize organisms according to their temperature regulation processes. One possible
2、division is between homeotherms and poikilotherms. As environmental temperature rises, homeotherms maintain an approximately constant body temperature, while the body temperature of poikilotherms varies with environmental temperature. One problem with this classification is that even classic homeoth
3、erms experience periods of reduced temperature., an alternative distinction between organisms is described below.Key NotesHomeotherms and poikilotherms外温 动物和内温动物像爬行动物等有机体属外温动物，它们很大程度地依赖于外来的热来提高自己的体温。内温动物是能够在体内产热以升高体温的有机体。鸟和哺乳动物属于这一类。 热中性区 （ thermoneutral zone） 是环境的温度范围，在这个温度范围内，内温动物仅使用一个最小的代谢率以维持恒定的
4、体温。环境温度离热中性区越远，内温动物维持恒定体温消耗的能量越多。热 交 换 所有的有机体从它们的环境中得到热，也将产生的热散失到它们的环境中。种种生理学和行为学的机理被用于调节体热。尽管有这些机理，外温性动物的体温还是明显地随环境条件而改变。Ectotherms are organisms such as plants, reptiles and protista which are largely reliant on external sources of heat to raise their body temperature.endotherms are organisms capa
5、ble of generating heat internally in order to raise their body temperature. Birds and mammals make up this group. The thermoneutral zone is the range of enmironmental temperatures in which an endotherm has only to exert a minimum metabolic effort in order to maintain a constant body temperature. The
6、 further away from the thermoneutral zone that the environmental temperature moves, the more energy the endotherm has to expend to maintain body temperature. Ectotherms and endothermsAll organisms gain heat from and lose heat to their environment as well as producing heat. A variety of physiological
7、 and behavioral mechanisms are used to regulate heat. Despite these mechanisms, the body temperature of an ectotherm varies significantly with environmental conditions.Heat exchange温 度 阈 高温可能导致酶失活或代谢组分不平衡，例如植物的呼吸作用快于光合作用而导致死亡。然而高温对外温动物最普遍的影响是引起脱水。所有陆生外温动物必须保持水，但在高温下失水率能够成为致死因子。不同物种对低温的耐受性有很大的差异，这与结冰
8、、寒冷和坚硬的过程有关。温度低于 -1 时很多物种被冻死，这是由于细胞内冰晶形成的损伤效应；那些生活在整个冰冻冬天的种，经常是处于一种有抵抗力的休眠时期，这是它们生命周期中的一个阶段。相关题目 太阳辐射与气候（ C1） 对温度的响应（ E2） 植物与水（ D2） 温度与物种分布（E3） 动物与水（ D3） 生态系统格局（ S1）High temperatures may lead to enzyme inactivation or the unbalancing of components of metabolism; for example, in plants, respiration m
9、ay proceed faster than photosynthesis, leading to death, however, the most frequent effect of high temperature on ectotherms is dehydration. All terrestrial ectotherms must conserve water but at high temperatures rates of water loss can be lethal. There are large differences between the low temperat
10、ure tolerances of differing species, associated with the processes of freezing, chilling and hardening. Many are killed by temperatures below 1 due to the damaging effects of ice-crystal formation within cells; those that live through freezing winters often do so at a resistant, dormant stage of the
11、ir life cycle.Temperature thresholdsRelated topics Solar radiation and climate(C1) Responses to temperature (E2)Plants and water (D2) Temperature and species Animals and water (D3) distribution (E3)Ecosystem patterns (S1)E2 对 温度的响应要 点温度和酶反应速度酶催化反应的速度随温度而增加。在外温动物中这意味着在较高的温度中代谢活力更快。温度系数（ Q 10) 是温度升高 10 对代谢速度影响的指数，经常大约为2.0。发育和生长的速度在非致死温度范围内，温度对外温动物最大的影响很可能是影响了发育和生长的速度。当用发育速度对体温做图时，存在着一个直线相关的温度范围。 “生理时间 ”是将温度和时间相结合的一个测量，应用于外温动物，它反应了这些有机体的生长和发育依赖于温度及时间。
