The space between the stars is filled with matter that interstellar conditions should prevent from coalescing into solid particle. Yet surprisingly tiny frozen particles, referred to as interstellar grains, do develop in these spaces. These grains are formed out of chemical elements that are synthesized during thermonuclear fusion in stars and supernova explosions.
The study of interstellar grains has been hampered by the inaccessibility of naturally occurring specimens for use in laboratory experiments. To date, the only source of information about interstellar grains is the stellar electromagnetic radiation that reaches the Earth after passing through regions of space containing interstellar grains. By observing the wavelengths scattered and absorbed by the grains,scientists have determined that a grain`s internal structure consists of a core composed of silicates (rocklike material) and a mantle composed entirely of organic compounds. It is hypothesized that each grain begins as a silicate "seedling" ejected from a mature star. Continuous physical and chemical evolution then occurs in the mantle formed around the seedling.
|The author uses the tem "seedling" most probably in order to|
|Which of the following describe a process that is most similar to the evolution of an interstellar grain, as it is described in the passage?|
|It can be inferred from the passage that the method currently used to analyze the structure of an interstellar grain could best be described is|
|One of the legends that has been attached to the nineteenth-century writer Edgar Allan Poe is that he was addicted to morphine. Poe discussed virtually every known aspect of his life in his letters. However, nowhere in his voluminous correspondence does he mention his reputed morphine addiction. On the basis of this evidence, it is safe to conclude that reports of his supposed addiction are untrue.|
|Which of the following is an assumption on which the argument depends?|
|French-born avant-garde composer Edger Varese(1883-1965) coined the phrase "organized sound" to distinguish his bold sonic experiment, which called for howling sirens and electronically taped ambient noises from conventional music. Many of his contemporaries would not have accepted his works as music at all. But Varese didn`t regard himself as an iconoclast. He traced his heritage to music`s ancient practices, and professed admiration for the music of the Gothic Middle Ages. This seems appropriate, for the medieval composers shared his view of music as a technical unfitting of sound. Unlike the nineteenth-century Romantics, they would have had no problem with a discussion of music in terms of acoustic frequencies and intensities, rather than in terms of particular emotions associated with them.|
|The author would be most likely to agree with which of the following statements about Varese`s approach to composition?|
|The author alludes to the howling sirens featured in some of Varese`s works to|
|The period between the two world wars (1918-1939)was characterized by a broadening of the definition of women`s roles in the United States. In 1920 American women won the right to vote, building on this right, some now participated actively in politics. Increasing numbers of middle-class women joined their working-class contemporaries in the workplace, and a small but growing minority of them continued working after marriage. Divorce rates increased as work patterns and women`s expectations of marriage changed. While these trends continued throughout the interwar period, their momentum was slowed in its later years, as the prosperity of the 1920s abruptly ended. Many Americans responded to the economic crisis of the 1930s by reasserting traditional value that discouraged women from entering traditionally male occupations.|
|The author mentions divorce rates in order to|
|Which of the following can be inferred from the passage about American women in the workplace during the interwar period|
Disagreements among bacteriologists about the role in bacterial motility of the tail-like structures called flagella began in the late nineteenth century. Whereas many influential figures in bacteriology argued that flagella were motor organs, others saw them as useless appendages. The main evidence in favor of flagella as motor organs was only that they were seen on most motile species and were not found on nonmotile ones, yet this conclusion had come to be accepted by the overwhelming majority of bacteriologists before the 1930s. A 1946 paper by Adrianus Pijper challenged this consensus, reviving an old theory on the basis of new evidence. The argument on which the accepted view was based, Pijper asserted, was bad logic, for it was just as likely that flagella could be a product of motion as its cause. His observations suggested that the flagella must be merely twirls of polysaccharide material that, because of the active gyration of the cell body, spun out behind the cell as it swan. Further, his claim that movement is accomplished by undulations of a flexible cell body and that the flagella are a nonessential product of motility suggested a simple explanation for the existence of very motile bacteria without flagella.
Since flagella were taken to be an important feature for purposes of classification, Pijer`s claims called into question the fundamental taxonomy of bacterial species. Not only were the flagella not motor organs, according to Pijper`s argument, they were ephemeral and nonessential, so that all attempts to use them in taxonomic schemes were doomed to hopeless confusion. In addition, Pijper`s claims brought up another important issue whereas most of those interested in bacterial motility in the 1940s were asking whether electron microscopy(EM), the ultracentrifuge, or other high-tech tools just being introduced into biology could provide insight into this problem, Pijper specifically argued that these techniques could not get at the essence of motility, and that priority should be given to observations made on living cells.
In light of later evidence that confirmed that flagella actually are the motor organs of bacteria, it may be tempting to conclude that Pijper was simply being irrational. But at the time of the controversy, the evidence was still ambiguous, and it is clear that a preexisting commitment to the power and prestige of the electron microscope on the part of Pijper`s opponents was at least as important in their opposition as was the strength of the evidence per se. Whereas the two camps disagreed about who had superior evidence, they disagreed because they held fundamentally differing assumptions about biology. Reflected and intensified by the personal stakes involved in, they have tied their careers to the fortunes of a particular experimental system.
|It can be inferred that Pijper most likely supported his view of flagella by citing|
|According to the passage, Pijper`s claims about flagella are suggested in explanation for which of the following findings?|
|According to the passage, which of the following is true about that paper that Pijper wrote in 1946?|
|The passage suggests that Pijper and his opponents most likely agreed that|
|Modern scholarship`s view of women`s labor in Han dynasty China(206B.C.---A.D.220)shows women performing a wide variety of work roles. According to most modern scholars, for a household (the main economic organization in early Chinese society) to succeed economically, A man and a woman each had to work at many different kinds of gendered tasks. In contrast, writers during the Han dynasty, rather than emphasizing the multitude of daily tasks women performed, constructed an idealized representation of female labor, singling out cloth production as the most important job and linking it to the concept of successful womanhood. In reality, however, a woman who devoted herself to making cloth, ignoring other work, would have been considered irresponsible.|
|According to the passage, which of the following is true of Han dynasty writers` attitudes toward women and cloth production?|
|The author of the passage would be most likely to agree with which of the following evaluations of Han dynasty writers` views of labor?|