Directions: Each passage in this section is followed by a group of questions to be answered on the basis of what is stated or implied in the passage. For some of the questions, more than one of the choices could conceivably answer the question. However, you are to choose the best answer, that is, the response that most accurately and completely answers the question, and blacken the corresponding space on your answer sheet.
　　After thirty years of investigation into cell genetics, researchers made startling discoveries in the 1960s and early 1970s which culminated in the development of processes, collectively known as recombinant deoxyribonucleic acid (rDNA) technology, for the active manipulation of a cell’s genetic code. The technology has created excitement and controversy because it involves altering DNA—which contains the building blocks of the genetic code.
　　Using rDNA technology, scientists can transfer a portion of the DNA from one organism to a single living cell of another. The scientist chemically “snips” the DNA chain of the host cell at a predetermined point and attaches another piece of DNA from a donor cell at that place, creating a completely new organism.
　　Proponents of rDNA research and development claim that it will allow scientists to find cures for disease and to better understand how genetic information controls an organism’s development. They also see many other potentially practical benefits, especially in the pharmaceutical industry. Some corporations employing the new technology even claim that by the end of the century all major diseases will be treated with drugs derived from microorganisms created through rDNA technology. Pharmaceutical products already developed, but not yet marketed, indicate that these predictions may be realized.
　　Proponents also cite nonmedical applications for this technology. Energy production and waste disposal may benefit: genetically altered organisms could convert sewage and other organic material into methane fuel. Agriculture might also take advantage of rDNA technology to produce new varieties of crops that resist foul weather, pests, and the effects of poor soil.
　　A major concern of the critics of rDNA research is that genetically altered microorganisms might escape from the laboratory. Because these microorganisms are laboratory creations that, in all probability (in all probability: adv.很可能), do not occur in nature, their interaction with the natural world cannot be predicted with certainty. It is possible that they could cause previously unknown, perhaps incurable diseases. The effect of genetically altered microorganisms on the world’s microbiological predator-prey relationships is another potentially serious problem pointed out by the opponents of rDNA research. Introducing a new species may disrupt or even destroy the existing ecosystem. The collapse of interdependent relationships among species, extrapolated to its extreme, could eventually result in the destruction of humanity.
　　Opponents of rDNA technology also cite ethical problems with it. For example, it gives scientists the power to instantly cross evolutionary and species boundaries that nature took millennia to establish. The implications of such power would become particularly profound if genetic engineers were to tinker with human genes, a practice that would bring us one step closer to Aldous Huxley’s grim vision in Brave New World of a totalitarian society that engineers (策划，操纵) human beings to fulfill specific roles.
　　1. In the passage, the author is primarily concerned with doing which one of the following?
　　(A) explaining the process and applications of rDNA technology
　　(B) advocating continued rDNA research and development
　　(C) providing evidence indicating the need for regulation of rDNA research and development
　　(D) summarizing the controversy surrounding rDNA research and development
　　(E) arguing that the environmental risks of rDNA technology may outweigh its medical benefits
　　2. According to the passage, which one of the following is an accurate statement about research into the genetic code of cells?
　　(A) It led to the development of processes for the manipulation of DNA.
　　(B) It was initiated by the discovery of rDNA technology.
　　(C) It led to the use of new treatments for major diseases.
　　(D) It was universally heralded as a great benefit to humanity.
　　(E) It was motivated by a desire to create new organisms.
　　3. The potential benefits of rDNA technology referred to in the passage include all of the following EXCEPT
　　(A) new methods of waste treatment
　　(B) new biological knowledge
　　(C) enhanced food production
　　(D) development of less expensive drugs
　　(E) increased energy production
　　4. Which one of the following, if true, would most weaken an argument of opponents of rDNA technology?
　　(A) New safety procedures developed by rDNA researchers make it impossible for genetically altered microorganisms to escape from laboratories.
　　(B) A genetically altered microorganism accidentally released from a laboratory is successfully contained.
　　(C) A particular rDNA-engineered microorganism introduced into an ecosystem attracts predators that keep its population down.
　　(D) Genetically altered organisms designed to process sewage into methane cannot survive outside the waste treatment plant.
　　(E) A specific hereditary disease that has plagued humankind for generations is successfully eradicated.
　　5. The author’s reference in the last sentence of the passage to a society that engineers human beings to fulfill specific roles serves to
　　(A) emphasize the potential medical dangers of rDNA technology
　　(B) advocate research on the use of rDNA technology in human genetics
　　(C) warn of the possible disasters that could result from upsetting the balance of nature
　　(D) present Brave New World as an example of a work of fiction that accurately predicted technological developments
　　(E) illustrate the sociopolitical ramifications of applying genetic engineering to humans
　　6. Which one of the following, if true, would most strengthen an argument of the opponents of rDNA technology?
　　(A) Agricultural products developed through rDNA technology are no more attractive to consumers than are traditional crops.
　　(B) Genetically altered microorganisms have no natural predators but can prey on a wide variety of other microorganisms.
　　(C) Drugs produced using rDNA technology cost more to manufacture than drugs produced with traditional technologies.
　　(D) Ecosystems are impermanent systems that are often liable to collapse, and occasionally do so.
　　(E) Genetically altered microorganisms generally cannot survive for more than a few hours in the natural environment.