You should spend about 20 minutes on Question14-26 which are based on Reading Passage below.
A
The scientific study of twins goes back to the late 19th century, when Francis Galton, anearly geneticist, realized that they came in two varieties: identical twinsborn from one egg and non-identical twins that had come from two. That insightturned out to be key, although it was not until 1924 that it was used toformulate what is known as the twin rule of pathology, and twin studies reallygot going.
B
The twin rule of pathology states that anyheritable disease will be more concordant (that is, more likely to be jointlypresent or absent) in identical twins than in non-identical twins—and. in turn, will be more concordant in non-identical twins than innon-siblings. Early work, for example, showed that the statistical correlationof skin-mole counts between identical twins was 0.4, while non-identical twinshad a correlation of only 0.2. (A score of 1.0 implies perfect correlation,while a score of zero implies no correlation.) This result suggests that molesare heritable, but it also implies that there is an environmental component tothe development of moles, otherwise the correlation in identical twins would beclose to 1.0.
C
Twin research has shown that whether or not someonetakes up smoking is determined mainly by environmental factors, but once hedoes so, how much lie smokes is largely down to his genes And while a person'sreligion is clearly a cultural attribute, there is a strong genetic componentto religious fundamentalism. Twin studies arc also unraveling the heritabilityof various aspects of human personality. Traits from neuroticism and anxiety tothrill- and novelty-seeking all have large genetic components. Parentingmatters, but it does not determine personality in the way that some hadthought.
D
More importantly,perhaps, twin studies arc helping the understanding of diseases such as cancer,asthma, osteoporosis, arthritis and immune disorders. And twins can be used,within ethical limits, for medical experiments. A study that administered vitaminC to one twin and a placebo to the other found that it had no effect on thecommon cold. The lesson from all today's twin studies is that most human traitsare at least partially influenced by genes. However, for the most part, theage-old dichotomy between nature and nurture is not very useful. Many geneticprograms are open to input from the environment, and genes arc frequentlyswitched on or off by environmental signals. It is also possible that genesthemselves influence their environment. Some humans have an innate preferencefor participation in sports. Others are drawn to novelty. Might people also bedrawn to certain kinds of friends and types of experience? In this way, aperson's genes might shape the environment they act in as much as the environmentshapes the actions of the genes.
E
In the past, such research has beencontroversial. Josef Mengele, a Nazi doctor working at the Auschwitzextermination camp during the Second World War, was fascinated by twins. Hesought them out among arrivals at the camp and preserved them from thegas-chambers for a series of brutal experiments. After the war, Cyril Burt, aBritish psychologist who worked on the heredity of intelligence, tainted twinresearch with results that appear, in retrospect, to have been rather too good.Some of his data on identical twins who had been reared apart were probablyfaked. In any case, the prevailing ideology in the social sciences after thewar was Marxist, and disliked suggestions that differences in human potential mighthave underlying genetic causes. Twin studies were thus viewed with suspicion.
F
The ideological pendulum has swung back; however, as the human genome project and its aftermathhave turned genes from abstract concepts to real pieces of DNA. The role ofgenes in sensitive areas such as intelligence is acknowledged by all but a fewdie-hards. The interesting questions now concern how nature and nurtureinteract to produce particular bits of biology, rather than which of the two ismore important Twin studies, which are a good way to ask these questions, areback in fashion, and many twins are enthusiastic participants in this research.
G
Research at the Twinsburg festival began in a smallway, with a single stand in 1979. Gradually, news spread, and more scientistsbegan turning up. This year, half a dozen groups of researchers were lodged ina specially pitched research tent. In one corner of this tent. Paul Breslin,who works at the Monell Institute in Philadelphia, watched over several tables wheretwins sat sipping clear liquids from cups and making notes. It was the team'sthird year at Twinsburg. Dr Breslin and his colleagues want to find out howgenes influence human perception, particularly the senses of smell and tasteand those (warmth, cold, pain, tingle, itch and so on) that result fromstimulation of the skin. Perception is an example of something that is probablyinfluenced by both genes and experience. Even before birth, people are exposedto flavours such as chocolate, garlic, mint and vanilla that pass intact intothe bloodstream, and thus to the fetus. Though it is not yet clear whether suchpre-natal exposure shapes taste-perception there is evidence that it shapespreferences for foods encountered later in life.
H
However, there are clearly genetic influences at work,as well—for example in the ability to taste quinine.Some people experience this as intensely bitter, even when it is present atvery low levels. Others, whose genetic endowment is different, are lessbothered by it. Twin studies make this extremely clear. Within a pair ofidentical twins, cither both, or neither, will find quinine hard to swallow.Non-identical twins will agree less frequently.
I
On the other side of the tent Dennis Drayna, from the National Institute on Deafnessand Other Communication Disorders, in Maryland, was studying hearing. He wantsto know what happens to sounds after they reach the car. It is not clear, hesays, whether sound is processed into sensation mostly in the ear or in thebrain. Dr Drayna has already been involved in a twin study which revealed thatthe perception of musical pitch is highly heritable. At Twinsburg, he isplaying different words, or parts of words, into the left and right ears of histwinned volunteers. The composite of the two sounds that an individual reportshearing depends on how he processes this diverse information and that, DrDrayna believes, may well be influenced by genetics.
J
Elsewhere in the marquee, Peter Miraldi, of Kent StateUniversity in Ohio, was trying to find out whether genes affect an individual'smotivation to communicate with others. A number of twin studies have shown thatpersonality and sociability arc heritable, so he thinks this is fertile ground.And next to Mr. Miraldi was a team of dermatologists from Case Western ReserveUniversity in Cleveland. They are looking at the development of skin diseasesand male-pattern baldness. The goal of the latter piece of research is to findthe genes responsible for making men's hair fall out.
K
The busiest part of the tent, however, was the queue for forensic-science research intofingerprints The origins of this study are shrouded in mystery For many months,the festival's organizers have been convinced that the Secret Service—the American government agency responsible for, among other things, thesafety of the president—is behind it. When The Economistcontacted the Secret Service for more information, we were referred to SteveNash, who is chairman of the International Association for Identification(LAI), and is also a detective in the scientific investigations section of theMarin County Sheriffs Office in California. The LAI, based in Minnesota, is anorganization of forensic scientists from around the world. Among other things,it publishes the Journal of Forensic Identification.
Questions 14-18
The reading Passage has paragraphs A-K
Which paragraph contains the following information?
Write the correct letter A-K, in boxes 14-18 on youranswer sheet
NB Youmay use any letter more than once.
14. Mentioned research conducted in Ohio
15. Medical contribution to the researches for twins.
16. Research situation under life threatening conditions
17. Data of similarities of identical twins
18. Reasons that make one study unconvincing
Questions 19-20
Complete the following summary of the paragraphs ofReading Passage, using No More Than Two Words from the Reading Passage for eachanswer. Write your answers in boxes 19-20 on your answer sheet.
The first one that conducted research ontwins is called 19 . He separated twins into two categories: non identical andidentical twins. The twin research was used in medical application in as earlyas the year of 20.
Questions 21-23
Choose the correct letters in following options:
Write your answers in boxes 21-23 on your answersheet.
Please choose THREE research fields that hadbeen carried out in Ohio, Maryland and Twinsburgh?
A. Sense
B. Cancer
C. Be allergic to Vitamin D
D. Mole heredity
E. Sound
F. Boldness of men
Questions 24-26
Choose the correct letters in following options:
Write your answers in boxes 24-26 on your answersheet.
Please choose THREE results that had been verified inthis passage.
A. Non identical twins come from different eggs.
B. Genetic relation between identical twins is closerthan non-identical ones.
C. Vitamin C has evident effect on a cold.
D. Genetic influence to smoking is superior toenvironment's
E. If a pregnant woman cats too much sweet wouldlead to skin disease.
F. Hair loss has been found to be connected with skinproblem.
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