2. It can be inferred from the passage that by describing the Weddell seal as preparing “for the worst” (line 41), biologists mean that it
(A) prepares to remain underwater for no longer than twenty minutes
(B) exhibits physiological behavior similar to that which characterizes dives in which it heads directly for its prey
(C) exhibits physiological behavior similar to that which characterizes its longest dives in the wild.
(D) begins to exhibit predatory behavior
(E) clears the lactic acid from its blood before attempting to dive
3. The passage suggests that during laboratory dives, the pH of the Weddell seal’s blood is not adversely affected by the production of lactic acid because
(A) only those organs that are essential to the seal’s ability to navigate underwater revert to an anaerobic mechanism.
(B) the seal typically reverts to an anaerobic metabolism only at the very end of the dive
(C) organs that revert to an anaerobic metabolism are temporarily isolated from the seal’s bloodstream
(D) oxygen continues to be supplied to organs that clear lactic acid from the seal’s bloodstream
(E) the seal remains submerged for only short periods of time
4. Which of the following best summarizes the main point of the passage?
(A) Recent field studies have indicated that descriptions of the physiological behavior of the Weddell seal during laboratory dives are not applicable to its most typical dives in the wild.
(B) The Weddell seal has developed a number of unique mechanisms that enable it to remain submerged at depths of up to 500 meters for up to 70 minutes.
(C) The results of recent field studies have made it necessary for biologists to revise previous perceptions of how the Weddell seal behaves physiologically during its longest dives in the wild.
(D) Biologists speculate that laboratory studies of the physiological behavior of seals during dives lasting more than twenty minutes would be more accurate if the seals were not forcibly submerged.
(E) How the Weddell seal responds to oxygen deprivation during its longest dives appears to depend on whether the seal is searching for prey or avoiding predators during such dives.
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.英语作文
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