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Which of the following best describes the function of the first sentence in the author`s argument as a whole?
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Founder mutations are a class of disease-causing genetic mutations, each derived from its own ancestral "founder" in whom the mutation originated. While most disease-causing mutations are found in humans at a rate of one in a few thousand to one in a few million people, founder mutation can occur at much higher rates. This apparent anomaly is partially explained by the fact that most founder mutations are recessive: only a person with copies of the affected gene from both parents becomes ill. Most people with only one copy of the gene-"carriers"-survive and pass the gene to offspring. Furthermore, the single copy of a founder mutation often confers a survival advantage on carriers. For example, the hereditary hemochromatosis mutation protects carriers from iron-deficiency anemia because the mutated gene allows increased efficiency of iron absorption.
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The passage indicates which of the following about founder mutations?
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The author of the passage mentions the "hereditary hemochromatosis mutation" primarily in order to illustrate
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The recently announced discovery of the first known planet orbiting a pulsar (the ultradense, pulsating remnant off the supernova explosion of a star) turned out to be based on faulty data. Had this discovery been confirmed, theorists would have had difficulty accounting for the existence of such a planet. The supernova would certainly have destroyed any preexisting planets. This particular pulsar is relatively young, allowing little time for a new planet to have coalesced, and it rotates relatively slowly, implying that it has not interacted with any nearby star since the supernova.
But newer evidence of a different pulsar with planets is more promising. This is a rapidly spurring "millisecond pulsar" thought to be a much older object that has pulled gaseous material from a stellar neighbor, causing its rotational speed to increase. Leftover, unconsumed gas around such a pulsar could, in theory, coalesce into planets. Or the pulsar`s radiation might have vaporized a companion star, providing new material for planetary formation.
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The primary purpose of the passage is to
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Which of the following best describe the organization of the passage?
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Which of the following can be inferred regarding the pulsar discussed in the first paragraph?
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In 1838, twenty-nine years before publishing his translation of Dante`s Inferno, Henry Wadsworth Longfellow wrote that "to understand Dante- it is absolutely necessary to understand the Italian Language." How true was Longfellow to his own dictum? Judging by the problems he had in composing a simple inscription, his ability to express himself in Italian was probably modest. However, this does not mean his understanding of the written language was inadequate. Longfellow`s translation is on the whole not only correct but accurate and attentive to the semantic nuances of the original. Indeed, the literalness of his translation shows he understood Dante`s language so well that he felt duty bound to render into English its extraordinary precision, richness, and variety.
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The author cites Longfellow`s remarks from 1838 in order to
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Which of the following does the author cite as support in assessing Longfellow`s knowledge of the Italian language?
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Marine ecosystems certainly have less permanence than terrestrial ecosystems. Ashore, ecologists are not confronted with shifting ecological discontinuities, or with changes in the characteristic conditions of individual ecosystems, because, unless man intervenes, the tree line on a mountain or the passage between grassland and savannah remains approximately static over a human lifetime. It is only on the millennial scale that such boundaries migrate significantly, or that characteristic regional ecosystems disappear. Urban sprawl, deforestation, overgrazing, and intensive agriculture are accomplishing in a few decades what nature cannily do in centuries, but that sad fact does not alter the argument. Although the human population explosion can produce pressures that rapidly shift ecological boundaries and modify ecosystems ashore, it is paradoxically more difficult directly to modify the average locations of the ephemeral and shifting ecological boundaries of the sea. We can accomplish this only indirectly by atmospheric modification, resulting in a changed global climate and a shifted ocean circulation.
Indeed, if we are agreed that the regional characteristics of marine ecosystems are consequent on the characteristics of the physical environment, then we must assume that ecological conditions are as impermanent as the physical conditions themselves. And these, it is now well understood, are in continual flux and state of change at all scales of variability.
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The primary purpose of the passage is to
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The passage indicates which of the following about the "ecological boundaries of the sea?"
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W.E.B. Du Bois` exhibit of African American history and culture at the 1900 Paris Exposition Universelle attracted the attention of a world of sociological scholarship whose value his work challenged. Du Bois believed that Spencerian sociologists failed in their attempts to gain greater understanding of human deeds because their work examined not deeds but theories and because they gathered data not to affect social progress but merely to theorize. In his exhibit, Du Bois sought to present cultural artifacts that would shift the focus of sociology from the construction of vast generalizations to the observation of particular, living individual elements of society and the working contributions of individual people to a vast functioning social structure.
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The passage implies that Du Bois attributed which of the following beliefs to Spencerian sociologists?
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The passage implies that Du Bois believed which of the following statements about sociology?
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Favorable environments do not necessarily lead to the occurrence of plant cultivation. South China is warmer and moister than North China and the Yangtze Basin, with wild rice and highly abundant natural resources. Yet archaeological data indicate that cereal cultivation did not occur in this region until approximately 7,000 to 6,500 years ago. This cultivation was likely a result of cultural contact with and expansion from the Yangtze Basin. Clearly, environmental factors were important for the occurrence of cultivation in China, but were not the absolute determining factors. While incipient cultivation might occur in areas of relatively abundant resources, it may not occur in areas of very abundant resources, such as South China, where foraging might be a more efficient way of life.
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The author implies which of the following about natural resources in South China prior to 6,500 years ago?
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Which of the following can be inferred from the passage about plant cultivation in the Yangtze Basin?
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