新题型模拟练习

　　Directions:

　　In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of numbered blanks. There are two extra choices, which do not fit in any of the blanks. Mark your answers on ANSWER SHEET 1. (10 points)

　　Researchers have found that genes play a large role in shaping a child’s emotional makeup, but a child’s personality traits are also profoundly affected by his or her environment. Genetic and environmental factors combine in complex ways to shape a child’s psychological development.

　　The wizards of genetics keep closing in on the biological roots of personality. It’s not your imagination that one baby seems born cheerful and another morose. But that’s not the complete picture. (41) ___________________________.

　　In the last few years scientists have identified genes that appear to predict all sorts of emotional behavior, from happiness to aggressiveness to risk-taking. (42) __________________. But the answer may not be so simple after all. Scientists are beginning to discover that genetics and environment work together to determine personality as intricately as Astaire and Rogers danced. Nature affects nurture affects nature and back and forth. Each step influences the next.

　　(43) ___________________________. An aggressive toddler, under the tight circumstances, can essentially be rewired to channel his energy more constructively. A child can overcome her shyness—forever. No child need be held captive to her genetic blueprint. The implications for child rearing—and social policy—are profound.

　　While Gregor Mendel’s pea plants did wonders to explain how humans inherit blue eyes or a bald spot, they turn out to be an inferior model for analyzing something as complex as the brain. (44) ___________________________. Genes control the brain’s neurotransmitters and receptors, which deliver and accept mental messages like so many cars headed for their assigned parking spaces. But there are billions of roads to each parking lot, and those paths are highly susceptible to environmental factors.

　　(45) ___________________________.

　　Children conceived during a three-month famine in the Netherlands during a Nazi blockade in 1945 were later found to have twice the rate of schizophrenia as did Dutch children born to parents who were spared the trauma of famine. “Twenty years ago, you couldn’t get your research funded if you were looking for a genetic basis for schizophrenia, because everyone knew it was what your mother did to you in the first few years of life, as Freud said,” says Robert Plomin, a geneticist at London’s Institute of Psychiatry. “Now you can’t get funded unless you’re looking for a genetic basis. Neither extreme is right, and the data show why. There’s only a 50 percent concordance between genetics and the development of schizophrenia.”

　　［A］ Many scientists now believe that some experiences can actually alter the structure of the brain.

　　［B］ Meanwhile, genetic claims are being made for a host of ordinary and abnormal behaviors, from addiction to shyness and even to political views and divorce. If who we are is determined from conception, then our efforts to change or to influence our children may be futile. There may also be no basis for insisting that people behave themselves and conform to laws. Thus, the revolution in thinking about genes has monumental consequences for how we view ourselves as human beings.

　　［C］ DNA is not destiny; experience plays a powerful role, too.

　　［D］ A gene is only a probability for a given trait, not a guarantee. For that trait to be expressed, a gene often must be “turned on” by an outside force before it does its job. High levels of stress apparently activate a variety of genes, including those suspected of being involved in fear, shyness and some mental illnesses.

　　［E］ The human body contains about 100,000 genes, of which 50,000 to 70,000 are involved in brain function.

　　［F］ The inextricable interplay between genes and environment is evident in disorders like alcoholism, anorexia, or overeating that are characterized by abnormal behaviors. Scientists spiritedly debate whether such syndromes are more or less biologically driven. If they are mainly biological—rather than psychological, social, and cultural—then there may be a genetic basis for them.

　　［G］ The age-old question of whether nature or nurture determines temperament seems finally to have been decided in favor of Mother Nature and her ever-deepening gene pool.

　　参考答案：41 C 42 G 43 A 44 E 45 D