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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(私生)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 corms 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(家谱) 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 ease 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 Molecular Genealogy Research Group is building a database for the purpose of______.
选项 A、offering assistance in working out genealogy-related problems
B、solving many issues without relying on traditional written records
C、providing a pedigree chart of at least four generations in the world
D、confirming the assumption that all individuals are of the same origin
答案A
解析 题干问的是建数据库的目的，对照第二段第四行中“help in solving many issues regarding genealogies that could not be done by relying only...(有助于解决仅靠……不能解决的与宗谱有关的许多问题)”。四个选项：A“解决与宗谱有关的问题时提供帮助”，正确；B“无须依赖传统文字资料解决许多问题”；C“提供代表世界基因构成的家谱”；D“获得10万份世界各地个人DNA样本”均不正确。
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大学英语四级

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