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lampbrush chromosome (灯刷染色体)
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第一篇IQ-GeneIn the angry debate over how much of IQ comes from the genes that children inherit from parents and how much comes from experiences,one little fact gets overlooked:no one has identified any genes(other than those that cause retardation)that affect intelligence.So researchers led by Robert Plomin of London's Institute of Psychiatry decided to look for some.They figured that if you want to find a"smart gene",you should look in smart kids.They therefore examined the DNA of students like those who are so bright that they take college entrance exams four years early一and still score at Princeton-caliber levels.The scientists found what they sought."We have,"says Plomin, "the first specific gene ever associated with general intelligence."Plomin's colleagues drew blood from two groups of 51 children each,all 6 to 15 years old and living in six countries around Cleveland.In one group,the average IQ is 103.All the children are white.Isolating the blood cells,the researchers then examined each child's chromosome 6.Of the 37 land marks on chromosome 6 that the researchers looked for,one jumped out:a form of gene called IGF2R occurred in twice as many children in the high-IQ group as in the average group—32 percent versus 16 percent.The study,in the May issue of the journal Psychological Science concludes that it is this form of the IGF2R gene that contributes to intelligence.Some geneticists see major problems with the IQ-gene study.One is the possibility that Plomin's group fell for"chopsticks fallacy".Geneticists might think they've found a gene for chopsticks flexibility,but all they've really found is a gene more common in Asians than,say,Africans. Similarly, Plomin's IQ gene might simply be one that is more common in groups that emphasize academic achievement."What is the gene that they've found reflects ethnicity?"asks geneticist Andrew Feinberg of Johns Hopkins University."That alone might explain the link to intelligence,since IQ tests are known for being culturally sensitive and affected by a child's environment."And Neil Risch of Standford University points out that if you look for 37 genes on chromosome,as the researchers did, and find that one is more common in smarter kids,that might reflect pure chance rather than a causal link between the gene and intelligence.Warns Feinberg:"I would take these findings with a whole box of salt."Plomin's IQ-gene study is similar to the chopsticks gene finding in that_______.A:there may not be a causal link between gene and intelligenceB:there is close correlation between gene and intelligenceC:there may be a close relation between chopsticks flexibility and children's academic scoreD:there is not a close relation between chopsticks flexibility and children's academic score
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灯刷染色体是哪一时期的卵母细胞染色体（）A、细线期（leptotene）B、合线期（zygotene）C、粗线期（pachytene）D、双线期（diplotene）E、终变期（diakinesis）
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单选题有关多线染色体和灯刷染色体的说法中，正确的是（）。A
二者都不能进行转录B
灯刷染色体上，每个基因至少有4个拷贝C
多线染色体带的包装程度比间带低D
灯刷染色体上的轴丝由RNA组成
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名词解释题染色体畸变分析（chromosome aberration analysis）
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