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题库解析   >   细节题题型   >   RC456-470
    本题由hyman1提供
155次学习
RC456-470

Resin is a plant secretion that hardens when exposed to air; fossilized resin is called amber. Although Pliny in the first century recognized that amber was produced from "marrow discharged by trees," amber has been widely misunderstood to be a semiprecious gem and has even been described in mineralogy textbooks. Confusion also persists surrounding the term "resin,"which was defined before rigorous chemical analyses were available. Resin is often confused with gum, a substance produced in plants in response to bacterial infections, and with sap, an aqueous solution transported through certain plant tissues. Resin differs from both gum and sap in that scientists have not determined a physiological function for resin.

In the 1950s, entomologists posited that resin may function to repel or attract insects. Fraenkel conjectured that plants initially produced resin in nonspecific chemical responses to insect attack and that, over time, plants evolved that produced resin with specific repellent effects. But some insect species, he noted, might overcome the repellent effects, actually becoming attracted to the resin. This might induce the insects to feed on those plants or aid them in securing a breeding site. Later researchers suggested that resin mediates the complex interdependence, or "coevolution," of plants and insects over time. Such ideas led to the development of the specialized discipline of chemical ecology, which is concerned with the role of plant chemicals in interactions with other organisms and with the evolution and ecology of plant antiherbivore chemistry (plants' chemical defenses against attack by herbivores such as insects).

【OG20-P433-541题】

The author refers to "bacterial infections" most likely in order to (highlight)

    <p>(A) describe the physiological function that gum performs in plants</p><p>&nbsp;</p><p>(B) demonstrate that sap is not the only substance that is transported through a plants tissues</p><p>&nbsp;</p><p>(C) explain how modern chemical analysis has been used to clarify the function of resin</p><p>&nbsp;</p><p>(D) show that gum cannot serve as an effective defense against herbivores</p><p><br/></p><p>(E) give an example of how confusion has arisen with regard to the nature of resin</p><p><br/></p><p><br/></p>
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答案:
A

这一题比

较简单,选A  我们直接在原文里找到原句 Resin is often confused with gum, a substance produced in plants in response to bacterial infections, 我们可以看见 bacterial infections 出现在了 “gum”的同位语部分里,所有都是用来解释 gum 的属性, 对于本文结构或观点或走向并没有起到什么作用, 所以答案一目了然选A

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