新东方优美背诵短文5 0 篇 Un i t50:Ce l l s and T emperat ure50、 Cell s an d T e m p era t ur e ?Cells cannot re m ain ali ve out s ide certa i n li m its of t e mpe r atu r e and much n arr o wer lim i ts m a r k the bou n dar ies of e f f ec t i ve fun c tio ni ng、 Enzyme systems of mam m als and bir ds a r e m os t effi c ient only wit h in a narr o w r ange a r o u nd 37 C;a de partu re of a f ew d egrees f rom t h is value s e r i ous l y i m p airs t heir functioning、 Even tho u gh cel l s ca n su r vi v e w i der fl u ct u ations the i ntegra te d a cti o ns o f bo d ily s ystems ar e impai r e d、 Other a n ima l s h a ve a wi d er t ol era nc e for chang e s o f bodily temper a tur e、 For c e nturies it h a s b een recogn i zed t h a t mam m als and birds di f f e r from other ani m als in th e w ay th ey regul a te bo d y t empe rat u re、 W a y s o f c haracterizing th e dif f erenc e ha v e b ee more a cc urate and m eaningful ov e r time, but p opula r te r m i n o logy st il l refle c ts the old d iv i s i on i n to “w a rm-bl o od e d” a n d “co l d—b loo d ed” specie s; warm-b l oo d ed i nclu ded ma mmals and birds w hereas all ot her c r e a tu r es we re con s idered c old-blood ed、 A s mo r e s pecies were stud i ed, i t became e vide n t th a t this cl assifi c ati on w a s inade q u ate、 A f e n ce liza r d or a de...