具有一对相对性状差异的个体杂交，后代产生3：1的条件是什么？
参考答案：
具有一对相对性状差异的个体杂交，后代产生3：1的条件是：双亲都必须是同质结合的双倍体；所研究的相对性状是受一对等位基因控制的；等位基因之间具有完全的显隐性关系，而且不受其他基因的影响；F1产生的配子都发育很好，并可严格控制花粉来源；F2的个体都处于相似的环境下，所调查统计的F2群体较大。
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| In the clinic, I asked if Michael could be retested, so the specialist tested him again. To my 1 , it was the same score. Later that evening, I 2 told Frank what I had learned that day. After talking it over, we agree that we knew our 3 much better than an IQ (智商) test. We 4 that Michael's score must have been a 5 and we should treat him 6 as usual. We moved to Indiana in 1962, and Michael studied at Concordia High School in the same year. He got 7 grades in the school, especially 8 biology and chemistry, which was a great comfort. Michael 9 Indiana University in 1965 as a pre-medical student, soon afterwards, his teachers permitted him to take more courses than 10 . In 1968, he was accepted by the School of Medicine, Yale University. On graduation day in 1972, Frank and I 11 the ceremony (典礼) at Yale. After the ceremony, we told Michael about the 12 IQ score he got when he was six. Since that day, Michael sometimes would look at us and say 13 , "My dear mom and dad never told me that I couldn't be a doctor, not until after I graduated rom medical school!" It is his special way of thanking us for the 14 we had in him. Interestingly, Michael then 15 another IQ test. We went to the same clinic where he had 16 the test eighteen years before. This time Michael scored 126, an increase of 36 points. A result like that was supposed to be 17 . Children often do as 18 as what adults, particularly parents and teachers, 19 of them. That is, tell a child he is " 20 ", and he may play the role of a foolish child. | ||||
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