gre考试阅读真题解析(B)

　　A special mucous coating that serves as a chemical camouflage allows clown fish to live among the deadly tentacles of the unsuspecting sea anemone whose form, bright and varied colors, and cluster of tentacles superficially resemble a flower). Utterly dependent on this unlikely host for protection from predators, clown fish have evolved in isolated communities, a pattern that has led to unusual behavioral adaptations.

　　The rigidly defined hierarchy of each clown-fish community is dominated by a monogamous breeding pair consisting of the largest fish, a female, and the next largest, a male, attended by a fixed number of sexually immature fish ranging in size from large to tiny. A remarkable adaptation is that the development of these juveniles is somehow arrested until the hierarchy changes; then they grow in lockstep , maintaining their relative sizes. While the community thus economizes on limited space and food resources, life is risky for newly spawned clown fish. On hatching, the hundreds of larvae drift off into the plankton. If, within three weeks, the defenseless larval clown fish locates a suitable anemone , it may survive. However, if an anemone is fully occupied, the resident clown fish will repel any newcomer.

　　Though advantageous for established community members, the suspended and staggered maturation of juveniles might seem to pose a danger to the continuity of the community: there is only one successor for two breeding fish. Should one of a pair die, the remaining fish cannot swim off in search of a mate, nor is one likely to arrive. It would seem inevitable that reproduction must sometimes have to halt, pending the chance arrival and maturation of a larval fish of the appropriate sex.

　　This, however, turns out not to be the case. In experiments, vacancies have been contrived by removing an established fish from a community. Elimination of the breeding male triggers the prompt maturation of the largest juvenile. Each remaining juvenile also grows somewhat, and a minuscule newcomer drops in from the plankton. Removal of the female also triggers growth in all remaining fish and acceptance of a newcomer, but the female is replaced by the adult male. Within days, the males behavior alters and physiological transformation is complete within a few months. Thus, whichever of the breeding pair is lost, a relatively large juvenile can fill the void, and reproduction can resume with a minimal loss of time. Furthermore, the new mate has already proved its ability to survive.

　　This transformation of a male into a female, or protandrous hermaphroditism, is rare among reef fish. The more common protogynous hermaphroditism, where females change into males, does not occur among clown fish. An intriguing question for further research is whether a juvenile clown fish can turn directly into a female or whether it must function first as a male.

　　17. The passage is primarily concerned with

　　 analyzing the mutually advantageous relationship between two species

　　 comparing two forms of hermaphroditism among clown fish

　　 describing and explaining aspects of clown-fish behavior

　　 outlining proposed research on clown-fish reproduction

　　 attempting to reconcile inconsistent observations of clown-fish development

　　18. It can be inferred from the passage that the clown fish is able to survive in close association with the sea anemone because the

　　 sea anemone cannot detect the presence of the clown fish

　　 tentacles of the sea anemone cannot grasp the slippery clown fish

　　 sea anemone prefers other prey

　　 clown fish does not actually come within the range of the sea anemones tentacles

　　 clown fish has developed tolerance to the sea anemones poison

　　19. According to the passage, adult clown fish would be at a disadvantage if they were not associated with sea anemones because the clown fish would

　　 be incapable of sexual transformation

　　 be vulnerable to predators

　　 have no reliable source of food

　　 have to lay their eggs in the open

　　 face competition from other clown fish

　　20. It can be inferred from the passage that sex change would have been less necessary for the clown fish if

　　 the male clown fish were larger than the female

　　 each sea anemone were occupied by several varieties of clown fish

　　 many mature clown fish of both sexes occupied each sea anemone

　　 juvenile clown fish had a high mortality rate

　　 both male clown fish and female clown fish were highly territorial

　　21. The author mentions all of the following as characteristic of the rigidly defined hierarchy of the clown-fish community EXCEPT:

　　 At any time only one female clown fish can be reproductively active

　　 The mature clown fish are monogamous

　　 The growth of clown fish is synchronized

　　 The maximum number of clown fish is fixed

　　 There are equal numbers of male juveniles and female juveniles

　　22. Which of the following statements about newly hatched clown fish can be inferred from the passage?

　　 They develop rapidly.

　　 They remain close to the sea anemone occupied by their parents.

　　 They are more sensitive to chemical signals than are adult clown fish.

　　 They are not protected by their parents.

　　 They are less vulnerable to predation than are adult fish.

　　23. Which of the following, if true, would be LEAST consistent with the authors explanation of the advantage of hermaphroditism for clown fish?

　　 The number of individuals in a clown-fish community fluctuates significantly.

　　 Adult clown fish frequently cannibalize their young.

　　 The sea anemone tolerates clown fish only during a specific stage of the anemones life cycle.

　　 Juvenile clown fish rarely reach maturity.

　　 Clown-fish communities are capable of efficiently recruiting solitary adult clown fish.

　　Comparing designs in music with visual designs raises interesting questions. We are familiar with the easy transfers of terms denoting qualities from one field to another. The basic problem can be put this way: can music sound the way a design looks? The elements of music are not the same as those of painting. They may be analogous, but to be analogous is not to be identical. Is it possible, then, for the same broad characteristics to emerge from different perceptual conditions?

　　Two facts about the relation between broad characteristics of a work and their perceptual conditions must be kept distinct. First, the global characteristics of a visual or auditory complex are determined by the discernible parts and their relationships. Thus, any notable change in the parts or their relationships produces a change in some of the global characteristics. Second, a change in the parts or their relationships may leave other global characteristics unchanged.

　　24. In the first paragraph, the author is primarily concerned with establishing the fact that

　　 comparisons are not equations

　　 auditory phenomena are not visual phenomena

　　 frequently used comparisons are usually inaccurate

　　 careless perceptions result from careless thought

　　 questions concerning perception are psychological

　　25. In the passage, the author is primarily concerned with

　　 distinguishing mutually exclusive categories

　　 clarifying an apparent contradiction

　　 supporting new ideas

　　 analyzing a problem

　　 comparing opinions

　　26. The second paragraph is primarily concerned with establishing the idea that

　　 different global characteristics of a work result from the same discernible parts

　　 the parts of a work of art influence the total perception of the work

　　 visual and auditory characteristics can be combined

　　 changes in the parts of a work remain isolated from the work as a whole

　　 the visual complexes in a work of art influence the works auditory complexes

　　27. Which of the following statements is most likely be a continuation of the passage?

　　 The search for broad similarities thus begins by understanding and distinguishing these two facts.

　　 The search for musical-visual analogies thus depends on the complexity of the works being compared.

　　 The search for music and art of the highest quality thus depends on very different assumptions.

　　 Thus music and painting exist in mutually exclusive worlds.

　　 Thus music and painting are too complicated to be evaluated in terms of analogies.

答案：17-27：CABCEDEADBA