Tests

ESL, Niveau avancé

Solving Genetic Mysteries

All humans carry genetic information in the form of DNA. It is because of this huge ......... that scientists and historians have been able to identify ancient remains.
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However, there were limitations on the use of DNA. The analysis was only ......... to remains of a few thousand years old.
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Fortunately, this changed with the discovery of another technique for replicating genes. Using PCR, a researcher can take even the smallest sample and enlarge it into a ......... amount for analysis.
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With the discovery of PCR, scientists were able to accurately date well-preserved remains of ......... bones with the use of an automated sequencing machine that can interpret the genetic code.
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Researchers also discovered some mutations that occurred throughout history. Geneticists' used this evidence to determine that some of the mutational DNA had a ......... length of time.
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Scientists have discovered a few surprises when using stands of DNA. Samples taken from Neanderthal bones showed no link between ......... from that time period and modern humans.
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Mungo Man was a human whose remains were found in Australia in 2001. DNA dated him to be 41,000 years old, but having only slight ......... matches to modern day humans. Another surprise was that he was not the forefather of Australian Aborigines.
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One explanation given by researchers for the slight DNA match was that Mungo Man may have been part of a populus whose genetic ......... did not survive.
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Speculation for genetic "death" may have been dependent on the size of the village or group. Small groups would tend to retain similar DNA by ......... However, large groups would have a broader choice of mates, thus mixing DNA.
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Norwegian Vikings ......... Orkney Island, Scotlandin the 9th century, but they eventually settled there and left a genetic legacy which scientist found was a stronger DNA match with modern Norwegians than with their Scottish neighbors.
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