题目内容

【题目】果蝇的红眼（A）对白眼（a）为显性，控制眼色的基因位于X染色体上。双亲中一方为红眼，另一方为白眼，杂交后代中雌果蝇与亲代中雄果蝇的眼色相同，雄果蝇与亲代雌果蝇的眼色相同。下列相关叙述不正确的是（ ）

A．亲代雌果蝇和雄果蝇的体细胞中都存在等位基因

B．F1雌雄个体交配，F2中出现红眼果蝇的概率为3/4

C．F1雌雄个体交配，F2中各种表现型出现的概率相等

D．F2雌雄个体的基因型不是与亲代的相同，就是与F1的相同

【答案】B

【解析】分析题意可知，两个亲本的基因型为XaXa、XAY，F1雌雄个体的基因型分别为XAXa、XaY，F2个体的基因型为XAXa、XaY、XaXa、XAY，F2中出现红眼果蝇、白眼果蝇的概率均为1/2。

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