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  3. We all know that DNA has the ability to identify individuals but, because it is inherited, there are also regions of the DNA str

We all know that DNA has the ability to identify individuals but, because it is inherited, there are also regions of the DNA str

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问题    We all know that DNA has the ability to identify individuals but, because it is inherited, there are also regions of the DNA strand which can relate an individual to his or her family (immediate and extended), tribal group and even an entire population. Molecular Genealogy (宗谱学) can use this unique identification provided by the genetic markers to link people together into family trees. Pedigrees (家谱) based on such genetic markers can mean a breakthrough for family trees where information is incomplete or missing due to adoption, illegitimacy or lack of records. There are many communities and populations which have lost precious records due to tragic events such as the fire in the Irish courts during Civil War in 1921 or American slaves for whom many records were never kept in the first place.
   The main objective of the Molecular Genealogy Research Group is to build a database containing over 100,000 DNA samples from individuals all over the world. These individuals will have provided a pedigree chart of at least four generations and a small blood sample. Once the database has enough samples to represent the world genetic make-up, it will eventually help in solving many issues regarding genealogies that could not be done by relying only on traditional written records. Theoretically, any individual will someday be able to trace his or her family origins through this database.
   In the meantime, as the database is being created, molecular genealogy can already verify possible or suspected relationships between individuals. “For example, if two men sharing the same last name believe that they are related, but no written record proves this relationship, we can verify this possibility by collecting a sample of DNA from both and looking for common markers (in this case we can look primarily at the Y chromosome(染色体)),” explains Ugo A．Perego, a member of the BYU Molecular Genealogy research team.
The possible research of family trees is based on the fact that______.
选项 A、genetics has achieved a breakthrough
B、genetic information contained in DNA can be revealed now
C、each individual carries a unique record of who he is and how he is related to others
D、we can use DNA to prove how distant an individual is to a family, a group or a population
答案C
解析 语义理解推断题  基于第一段第二、三句，我们知道遗传标记提供独有的识别特征 (unique identification)把人们连接在一起，形成家族树。换句话说，能对家族树进行研究，是因为遗传标记的独有特征可以用来判断一个人的基因身份以及与他人之间的关系，[C]项正确。[A]“遗传学取得突破”和[B]“包含在DNA中的基因信息现在可以揭示出来”没有回答进行家族树研究依据什么基础这样的问题；而[D]项强调“用DNA证明……有多远(how distant)”与文章相悖。
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