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例1 基因型为HH的绵羊有角,基因型为hh的绵羊无角,基因型为Hh的绵羊,母羊无角,公羊有角。现有一头有角母羊生了一头无角小羊,这头小羊的性别及基因型分别是( )。 A.雄性,hh B.雌性,Hh C.雄性,Hh D.雌性,HH 解析 据题意可知,有角母羊的基因型一定为纯合体HH,那么其产生的卵细胞必含有H基因,即其产生的后代中至少含有一个H基因,而其所生小羊无角,所以,无角小羊的基因型应为Hh,性别应为雌性(因为基因型为HH无论公羊、母羊都有角)。
Example 1 Sheep with HH genotypes have horns, sheep with genotype hh have no horns, sheep with genotype Hh, ewes without horns, and rams with horns. There is a horned lamb with a hornless lamb. The sex and genotype of the lamb are (). A. male, hh B. female, Hh C. male, Hh D. female, HH analysis According to the meaning of the subject, the horned gama genotype must be homozygous HH, then the resulting egg cells must contain the H gene, ie The resulting offspring contains at least one H gene, and the resulting lamb does not have horns. Therefore, the hornless lamb should have a genotype of Hh, and the sex should be female (because the genotype is HH, regardless of whether the ram or ewes are Horned).