Passage 4Plant adaptation can be remarkably complex. Certain species of orchids, for instance, imitate female bees, other plants look and smell like animals, and still others have the appearance of stone. These strange adaptations to life represent just a few of the sophisticated means by which plants enhance their chances of survival.Mimicry in plants or animals is a three-part system. There is a model; the animal, plant, or substrate being imitated. There is a mimic; the organism that imitates the model. And there is a signal receiver or dupe; the animal that cannot effectively distinguish between the model and the mimic. Mimetic traits may include morphological structures, color patterns, behaviors, or other attributes of the mimic that promote its resemblance to a model. That model may be either an unrelated species or an inanimate objects such as the background against which an organism spends most of its time.Mimicry is not an active strategy on the part of an individual plant; flowers do no deliberately trick or deceive animals into visiting them. Mimicry arises as the result of evolution through natural selection and the occurrence of random generic mutations that lead over many generations to the appearance of favorable characteristics. If such traits help to camouflage a plant, for example, the plant is likely to have survival advantage over other plants that are less well camouflaged. The plant will leave more descendants, thereby passing the advantage to the next generation. For natural selection to favor the evolution of mimicry, the mimic must derive a reproductive advantage from modeling itself after another organism or object; its fitness, measured as the number of offspring produced that survive into the next generation must be increased as the result of deception. Which of the following is the best title for the passage().
A. How Mimicry Differs in Plants and Animals
B. New Development in the Theory of Evolution
C. Plants’ Strategy for Their Survival and Reproduction
D. The Nature and Evolution of Biological Mimicry in Plants
查看答案
Passage 2Throughout the nineteenth century and into the twentieth, citizens of the United States maintained a bias against big cities. Most lived on farms and in small towns and believed cities to be centers of corruption, crime, poverty, and moral degradation. Their distrust was caused, in part, by a national ideology that proclaimed farming the greatest occupation and rural living superior to urban living. This attitude prevailed even as the number of urban dwellers increased and cities became an essential feature of the national landscape. Gradually, economic reality overcame ideology. Thousands abandoned the precarious life on the farm for more secure and better paying jobs in the city. But when these people migrated from the countryside, they carried their fears and suspicions with them. These new urbanites, already convinced that cities were overwhelmed with great problems, eagerly embraced the progressive reforms that promised to bring order out of the chaos of the city.One of many reforms came in the area of public utilities. Water and sewerage system were usually operated by municipal governments, but the gas and electric networks were privately owned. Reformers feared that the privately owned utility companies would change exorbitant rates for these essential services and deliver them only to people who could afford them. Some city and state governments responded by regulating the utility companies, but a number of cities began to supply these services themselves. Proponents of these reforms argued that public ownership and regulation would insure widespread access to these utilities and guarantee a fair price.While some reforms focused on government and public behavior, others looked at the cities as a whole. Civic leaders, convinced that physical environment influenced human behavior, argued that cities should develop master plans to guide their future growth and development. City planning was nothing new, but the rapid industrialization and urban growth of the late nineteenth century took place without any consideration for order. Urban renewal in the twentieth century followed several courses. Some cities introduced plans to completely rebuild the city core. Most other cities contented themselves with zoning plans for regulating future growth. Certain parts of town were restricted to residential use, while others were set aside for industrial or commercial development. What does the passage mainly discuss().
A comparison of urban and rural life in the early twentieth century
B. The role of government in twentieth-century urban renewal
C. Efforts to improve urban life in the early twentieth century
D. Methods of controlling urban growth in the twentieth century
"They said what we always knew." Said an administration source, ().
A. he asked not to be named
B. who asked not to be named
C. who asked not be named
D. who asked not named
The editor spent hours () every single page of that hick novel, looking for the slightest error.
A. decorating
B. scrutinizing
C. remedying
D. shattering
Is it proper for the government to () public opinion through self-serving, one-sided journalism
A. touch
B. hunt
C. sway
D. proceed