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There is no consensus among researchers regarding what qualifies a substance as a pheromone. While most Line agree on a basic definition of pheromones (5) as chemicals released by one individual of a species which, when detected by another individual of the same species, elicit a specific behavioral or physiological response, some researchers also specify (10) that the response to pheromones must be unconscious. In addition, the distinction between pheromones and odorants— chemicals that are consciously detected as odors---can be blurry, and some (15) researchers classify pheromones as a type of odorant. Evidence that pheromone responses may not involve conscious odor perception comes from the finding that in many species, pheromones are processed (20) by the vomeronasal (or accessory olfactory) system, which uses a special structure in the nose, the vomeronasal organ (VNO), to receive chemical signals. The neural connections between the VNO and the (25) brain are separate from those of the main olfactory system, whose processing of odorants triggers sensations of smell. But while the VNO does process many animal pheromone signals, not all animal phero- (30) mones work through the VNO. Conversely, not all chemical signals transmitted via the VNO quality as pheromones. For example, garter snakes detect a chemical signal from earthworms—one of their favorite foods—via (35) the VNO, and they use this signal to track their prey. -------------------------------------------------------------------------------------------------- Q7 It can be inferred from the passage that in classifying pheromones as a type of odorant, the researchers referred to in line 15 posit that A. pheromones are perceived consciously B. most pheromones are processed by the VNO C. most chemical signals processed by the VNO are pheromones D. Pheromone perception does not occur exclusively between mem- bers of the same species. E. pheromones do not always elicit a specific behavioral or physio- logical response answer: ------------------------------------------------------------------------------------------------------- Q8 According to the passage, the fact that pheromones are processed by the VNO in many animal species has been taken as evidence of which of the following? A. The accessory and main olfac- Tory systems are not separate B. Odorants and pheromones are not distinct types of chemicals. C. Odorants and pheromones both elicit a specific behavioral response. D. Pheromones do not trigger con- scious sensations of smell. E. Pheromones aid animals in track- ing prey. Answer: ------------------------------------------------------------------------------------------------------- Q9 The primary purpose of the pas- sage is to A. compare and contrast the ways in which the vomeronasal organ and the main olfactory systern process chemicals. B. summarize the debate over the role the vomeronasal organ plays in odor perception C. present some of the issues involved in the debate over what constitutes a pheromone D. propose a new definition of pheromones based on recent research E. argue that pheromones should be classified as a type of odorant
第9题有点争议, 听听大家的意见. | 
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发表于 2006-8-21 11:51:00
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