2002-01 阅读45题 阅读比较费时间，实在是想不通了才拿出来麻烦大家 Questions 40-50 Pheromones are substances that serve as chemical signals between members of the same species. They are secreted to the outside of the body and cause other individuals of the species to have specific reactions. Pheromones, which are sometimes called Line "social hormones," affect a group of individuals somewhat like hormones do an individual (5) animal. Pheromones are the predominant medium of communication among insects (but rarely the sole method). Some species have simple pheromone systems and produce only a few pheromones, but others produce many with various functions. Pheromone systems are the most complex in some of the so-called social insects, insects that live in organized groups. (10) Chemical communication differs from that by sight or sound in several ways. Transmission is relatively slow (the chemical signals are usually airborne), but the signal can be persistent, depending upon the volatility of the chemical, and is sometimes effective over a very long range. Localization of the signal is generally poorer than localization of a sound or visual stimulus and is usually effected by the animal's moving (15) upwind in response to the stimulus. The ability to modulate a chemical signal is limited, compared with communication by visual or acoustic means, but some pheromones may convey different meanings and consequently result in different behavioral or physiological responses, depending on their concentration or when presented in combination. The modulation of chemical signals occurs via the elaboration of the number of exocrine (20) glands that produce pheromones. Some species, such as ants, seem to be very articulate creatures, but their medium of communication is difficult for humans to study and appreciate because of our own olfactory, insensitivity and the technological difficulties in detecting and analyzing these pheromones. Pheromones play numerous roles in the activities of insects. They may act as alarm (25) substances, play a role in individual and group recognition, serve as attractants between sexes, mediate the formation of aggregations, identify foraging trails, and be involved in caste determination. For example, pheromones involved in caste determination include the "queen substance" produced by queen honey bees. Aphids, which are particularly vulnerable to predators because of their gregarious habits and sedentary nature, secrete an alarm pheromone when attacked that causes nearby aphids to respond by moving away.
45. According to the passage, the meaning of a message communicated through a
pheromone may vary when the (A) chemical structure of the pheromone is changed (B) pheromone is excreted while other pheromones are also being excreted (C) exocrine glands do not produce the pheromone (D) pheromone is released near certain specific organisms 请问，这道题选哪个？XDF答案是A；一个网友更正的是B（根据line18）；我认为是C。
这到题也是偶曾经疑惑的，千想万想，找了个理由，觉得Ａ还是合适．第１８行是这个吧(红字)but some pheromones may
convey different meanings and consequently result in different behavioral or physiological
responses, depending on their concentration or when presented in combination这句话偶认为是关键，尤其是but转了一下，其中 concentration 有“浓度”之意，combination有“化合”之意，都是关于结构问题，所以，翻了一下---“但是一些激素传递着不同的意思，并且产生了一些不同的行动和生理机能的反映，这主要是根据他们的浓度和化合时呈现的不同的形式决定的”。这样的话是不是Ａ好些呢
我觉得The modulation of chemical signals occurs via the elaboration of the number of exocrine glands that produce pheromones.也是很关键的一句话。意思是不是说，根据pheromones的浓度或者化合形式决定它所传递的不同信息， 而化学信号的调整是通过一定数量外分泌腺体的共同作用（elaboration ）实现的 =〉因此，如果已有腺体在工作，又有其它腺体也分泌pheromones，那么化学信号就可以调整了 =〉B说的就是这个情况。
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发表于 2004-10-12 14:54:00
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