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Many herbivorous insects utilize plant resources during small windows of development or during short periods when plants are of suitable quality. Such temporal associations have been documented in numerous systems, where temporal constraints limit insect abundance and affect insect feeding strategy. Classic studies of winter moths, for example, suggest that the synchrony of larvae with leaf emergence is a primary determinant of larval success. Because many insect-plant associations have a temporal component, they may be negatively affected by environmental changes; some scientists fear, for example, that global warming may decouple insect-plant synchrony Hellman, however, notes that the timing of insect-plant synchrony is affected by many factors, including insects behavioral and physiological ability to adapt to changing host plant quality and the availability of alternative host resources.
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The "classic studies of winter moths" provide direct support for which of the following propositions
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The author discusses Hellman in the last sentence of the passage primarily in order to
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The large amount of methane in the atmosphere of Saturn's giant moon Titan puzzles astronomers. Because methane is converted into heavier hydrocarbons by the Sun's ultraviolet light, all the methane in Titan's atmosphere should, at the present conversion rate, have disappeared in a few million years, long ago in Titan's 4.5 billion years of existence. Something must be continuously feeding methane into Titan's atmosphere. One possibility is that the methane comes from volcanic eruptions, but unless the supply rate were somehow precisely calibrated at a moderate level, either the methane would have run out by now or excess methane would have started to accumulate as a liquid ocean on the Surface. However, data indicate that the atmosphere just above the surface is not humid, as would be expected above a pure methane ocean. A possible explanation was suggested by Lunine: when sunlight breaks down methane, the main product is ethane. Lunine noted that at Titan's surface temperature, ethane is also a liquid. A liquid mixture of methane and ethane would produce low Humidity. Such an ocean would slowly become richer in ethane while keeping the atmosphere supplied with methane.
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According to the passage,a mixture of liquid ethane and liquid methane on Titan could account for which of the following?
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The passage suggests that if the "possible explanation" is
correct, then which of the following would be true?
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The author of the passage introducas Lunine's hypothesis most likely in order to
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In seventeenth-century Venice, the invention of the opera house as a public institution altered the relationship of the audience to the operatic performance on the stage and to each other. The stage performance was now separated from the audience both by the proscenium arch, which framed the action, and by the orchestra. The occupants of the boxes faced one another across the auditorium as well as the stage. Seeing and being seen was as much a function of the opera house as seeing and hearing what took place on the stage. American visitors to Italy were routinely shocked at the casual ways of the boxholders and at the little attention they seemed to pay to the opera. There was incessant talk in the boxes, banging of doors, a restless to-and-fro.
Public display was only half the story. The public nature of Venice's social life was balanced by a passion for disguise. Much of its political activity was conducted in secrecy. Masks were usually worn during carnival, attracting the crowned heads of Europe, who could play there incognito. The Venetian opera box was the equivalent of the mask. With its door shut, with shutters
pulled across the front, the box became a place of privacy, an association that still exists in our time.
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The primary purpose of the passage is to
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According to the passage, the boxes of public opera houses
served to
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Regarding the"crowned heads of Europe," the author
implies which of the following?
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Some recently discovered Hittite tablets corroborate many of the descriptions of ancient life that appear in the lliad and even list Greek cities that reportedly sent ships to Troy. What this find entails is that the lliad is not simply creative literature, as is commonly believed, and hence not a matter for literary discussion alone. Rather, it is also history and should be examined by historical science.
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The argument given relles on which of the following as an assumption?
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From a biological perspective, culture may be broadly defined as shared variation in behavior that is generated and maintained by social learning-through imitation or
teaching, for example. Social learning in animals is often difficult to demonstrate directly. But the presence of culture can be established by observation and deduction: when behavioral differences exist that cannot be accounted for by genetic or environmental factors, cultural transmission must be occurring. Critics respond that it is often difficult to rule out hypotheses that genes or learned individual responses to differing environments are responsible for behavioral patterns. Often implicit in this argument is the notion that social learning, considered a more complex and more cognitively demanding phenomenon than individual learning, should be invoked only as an explanation of last resort.
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The passage suggests which of the following about individual learning?
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According to the passage, the occurrence of social learning
can be established by
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The source of vitamin C in the traditional Inuit diet was long a mystery. Most animals can synthesize vitamin C in their livers, but humans are among the exceptions. If humans do not ingest enough vitamin C the result is scurvy, a potentially fatal connective-tissue disease. Most Americans today get ample supplies from orange juice, citrus fruits, and fresh vegetables. But getting enough vitamin C from a ship's provisions was especially tricky for explorers voyaging to the Inuit' s native polar regions, and scurvy plagued European and United States expeditions there even in the twentieth century. However, Arctic peoples were free of the disease, even in the long winter, when they subsisted entirely on meat and fish they caught, often eaten raw.
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The passage suggests which of the following about humans' need for vitamin C?
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Which of the following, if true, most helps to resolve the mystery of the source of vitamin C in the traditional lnuit diet?
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The following passage comes from a study of gull bill markings.
Some species of gulls have uniformly colored bills, but many (62 percent in our sample) have beaks with differently colored tips, stripes, or spots that act as a focus for the pecking of newly hatched chicks as they beg for food. In an attempt to understand why, we determined whether adult gulls of those species with newly hatched chicks that are small in relation to the size of the adult are more likely to have such patterned
beaks. This work is based on Hailman' s (1967) suggestion that gulls with greater bill depths (large species) tend to have only a restricted area of red on the bill (i.e., a red tip or spot), whereas smaller-billed species have uniform bills. We suggest that the most plausible reason for any size-related difference is that concentrating a small chick's pecking on a particular part of the bill is more effective than is unfocused pecking in stimulating the adult to regurgitate food. As well as encouraging the chick to peck, the tip of the bill, or the gonys (where stripes and spots are located), might be more sensitive than are other parts of the beak to the feeble pecking of a small chick, or a small chick might more effectively occupy the parent's visual field when
pecking there.
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