网络课堂总结(二十七)

会计考友

Passage 47 结论解释型（生命科学） 介绍存在电信号接受器Australian researchers have discovered electroreceptors clustered at the tip of the spiny anteater’s snout.（主题句） The researchers made this discovery by exposing small areas of the snout to extremely weak electrical fields（发现的方式） and recording the transmission of resulting nervous activity to the brain. While it is true（让步，看后半句） that tactile receptors， another kind of sensory organ on the anteater’s snout， can also respond to electrical stimuli， such receptors do so only in response to electrical field strengths about 1，000 times greater than*1 those known to excite electroreceptors.Having discovered the electroreceptors， researchers are now investigating how本段小主题：如何利用 anteaters utilize such a sophisticated sensory system. In one behavioral experiment*4， researchers successfully trained an anteater to distinguish between two troughs of water， one with a weak electrical field and the other with none. Such evidence is consistent with*4C researchers’ hypothesis that anteaters use electroreceptors to detect electrical signals given off by prey; however（转折）， researchers as yet have been unable to detect electrical signals emanating from termite mounds， where the favorite food of anteaters live. Still（转折，以最后一重转折为准）， researchers have observed anteaters breaking into a nest of ants*5 at an oblique angle ) and quickly locating nesting chambers. This ability quickly*5E to locate unseen prey suggests*5A， according to the researchers， that the anteaters were using their electroreceptors to locate the nesting chambers.

1. According to the passage， which of the following is a characteristic that distinguishes*1 electroreceptors from tactile receptors?（第一段最后一句）
The manner in which electroreceptors respond to electrical stimuli
/ T, i) G% b5 ?' ^3 M$ rThe tendency of electroreceptors to be found in clusters
The unusual locations in which electroreceptors are found in most species
The amount of electrical stimulation required to excite electroreceptors区别在于电场的强度大小（D）
/ u! \- V9 v% p. Q5 o7 s  CThe amount of nervous activity transmitted to the brain by electroreceptors when they are excited