关于小安阅读的第29篇第五题

GaeaLee

Studies of the Weddellseal in the laboratory have described the physiological mechanisms that allowthe seal to cope with the extreme oxygen deprivation that occurs during itslongest dives, which can extend 500 meters below the ocean’s surface and lastfor over 70 minutes. Recent field studies, however, suggest that during moretypical dives in the wild, this seal’s physiological behavior is different.

In the laboratory,when the seal dives below the surface of the water and stops breathing, itsheart beats more slowly, requiring less oxygen, and its arteries becomeconstricted, ensuring that the seal’s blood remains concentrated near thoseorgans most crucial to its ability to navigate underwater. The seal essentiallyshuts off the flow of blood to other organs, which either stop functioninguntil the seal surfaces or switch to an anaerobic (oxygen-independent)metabolism. The latter results in the production of large amounts of lactic acid (lacticacid: n.乳酸) which can adversely affect the pH of the seal’s blood, but sincethe anaerobic metabolism occurs only in those tissues which have been isolatedfrom the seal’s blood supply, the lactic acid is released into the seal’s bloodonly after the seal surfaces, when the lungs, liver, and other organs quicklyclear the acid from the seal’s bloodstream.

Recent fieldstudies, however, reveal that on dives in the wild, the seal usually headsdirectly for its prey and returns to the surface in less than twenty minutes.The absence of high levels of lactic acid in the seal’s blood after such divessuggests that during them, the seal’s organs do not resort to the anaerobicmetabolism observed in the laboratory, but are supplied with oxygen from theblood. The seal’s longer excursions underwater, during which it appears to beeither exploring distant routes or evading a predator, do evoke the divingresponse seen in the laboratory. But why do the seal’s laboratory dives alwaysevoke this response, regardless of their length or depth? Some biologistsspeculate that because in laboratory dives the seal is forcibly submerged, it does not knowhow long it will remain underwater and so prepares for the worst.

5.     According to the author, which of thefollowing is true of the laboratory studies mentioned in line1?（此题狡猾！）

(A) They failto explain how the seal is able to tolerate the increased production of lacticacid by organs that revert to an anaerobic metabolism during its longest divesin the wild.

(B) Theypresent an oversimplified account of mechanisms that the Weddell seal relies onduring its longest dives in the wild.

(C) Theyprovide evidence that undermines the view that the Weddell seal relies on ananaerobic metabolism during its most typical dives in the wild.

(D) They arebased on the assumption that Weddell seals rarely spend more than twentyminutes underwater on a typical dive in the wild.（E）

(E) Theyprovide an accurate account of the physiological behavior of Weddell sealsduring those dives in the wild in which they are either evading predators orexploring distant routes.

答案为什么是E啊？

1123LSYYSL

我也觉得好奇怪啊 为什么第二个不对

Blair__Lu

B为什么不对“Recent field studies, however, reveal that on dives in the wild, the seal usually headsdirectly for its prey and returns to the surface in less than twenty minutes.

E从哪里来”The seal’s longer excursions underwater, during which it appears to beeither exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory.