阅读大全63篇第29篇第5题

sanlingjie

第五题我完全不知道怎么会选E。我原来选的B，但是现在发现B也不对，可是E也不知道正确在哪里，请高手们帮忙解释一下。。。。太久没人回答问题了。。
Studies of the Weddell seal in the laboratory have described the physiological mechanisms that allow the seal to cope with the extreme oxygen deprivation that occurs during its longest dives, which can extend 500 meters below the ocean’s surface and last for over 70 minutes. Recent field studies, however, suggest that during more typical 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, its heart beats more slowly, requiring less oxygen, and its arteries become constricted, ensuring that the seal’s blood remains concentrated near those organs most crucial to its ability to navigate underwater. The seal essentially shuts off the flow of blood to other organs, which either stop functioning until the seal surfaces or switch to an anaerobic (oxygen-independent) metabolism. The latter results in the production of large amounts of lactic acid which can adversely affect the pH of the seal’s blood, but since the anaerobic metabolism occurs only in those tissues which have been isolated from the seal’s blood supply, the lactic acid is released into the seal’s blood only after the seal surfaces, when the lungs, liver, and other organs quickly clear the acid from the seal’s bloodstream.
Recent field studies, however, reveal that on dives in the wild, the seal usually heads directly 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 dives suggests that during them, the seal’s organs do not resort to the anaerobic metabolism observed in the laboratory, but are supplied with oxygen from the blood. The seal’s longer excursions underwater, during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory. But why do the seal’s laboratory dives always evoke this response, regardless of their length or depth? Some biologists speculate that because in laboratory dives the seal is forcibly submerged, it does not know how long it will remain underwater and so prepares for the worst.

5. According to the author, which of the following is true of the laboratory studies mentioned in line 1?
(A) They fail to explain how the seal is able to tolerate the increased production of lactic acid by organs that revert to an anaerobic metabolism during its longest dives in the wild.
(B) They present an oversimplified account of mechanisms that the Weddell seal relies on during its longest dives in the wild.
(C) They provide evidence that undermines the view that the Weddell seal relies on an anaerobic metabolism during its most typical dives in the wild.
(D) They are based on the assumption that Weddell seals rarely spend more than twenty minutes underwater on a typical dive in the wild.
(E) They provide an accurate account of the physiological behavior of Weddell seals during those dives in the wild in which they are either evading predators or exploring distant routes.

mary17

文中说The seal’s longer excursions underwater, during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory.

和E一样

蓝狮爱我

up，没懂

xyc19901015

顶一个~

cecilia422

呼呼~刚好做到这篇，贴下我自己做的笔记，有点乱。。

提出新观点Recent field studies, however（新老观点的分歧）, reveal that on dives in the wild, the seal usually heads directly 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 dives suggests that during them, the seal’s organs do not resort to the anaerobic metabolism observed in the laboratory（新观点的中心句）, but are supplied with oxygen from the blood. The seal’s longer excursions underwater, Q5 during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory（与老观点的相似点）. But（接下来解释分歧，要仔细读） why do the seal’s laboratory dives always evoke this response, regardless of their length or depth? Some biologists speculate that because in laboratory dives the seal is forcibly submerged, Q2 it does not know how long it will remain underwater and so prepares for the worst.



在很多情况下，seal的潜水不需要很长时间 (less than 20 min.，举例search for its prey) ==> 没有出现大量的乳酸 ==> 不是采用无氧模式，而是血液中的氧气==>不缺氧，与实验室的结果不符合

只有在longer excursions underwater(举例，有两种原因)，才出现和实验室一样的结果==>
所以，实验室的结果depends on Time

我觉得E项对应的就是do evoke the diving response seen in the lab这句话里面举的两个例子吧~