[题目]鸡的性别决定方式属于ZW型.母鸡的性染色体组成是ZW.公鸡是ZZ.现有一只纯种雌性芦花鸡与一只纯种雄性非芦花鸡交配多次.F1中雄鸡均为芦花形.雌鸡均为非芦花形.据此推测错误的是 ( )A．控制芦花和非芦花性状的基因在Z染色体上.而不可能在W染色体上B．雄鸡中芦花鸡所占的比例比雌鸡中的相应比例大C．让F1中的雌雄鸡自由题目和参考答案——青夏教育精英家教网—

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【题目】鸡的性别决定方式属于ZW型，母鸡的性染色体组成是ZW，公鸡是ZZ。现有一只纯种雌性芦花鸡与一只纯种雄性非芦花鸡交配多次，F1中雄鸡均为芦花形，雌鸡均为非芦花形。据此推测错误的是（）

A．控制芦花和非芦花性状的基因在Z染色体上，而不可能在W染色体上

B．雄鸡中芦花鸡所占的比例比雌鸡中的相应比例大

C．让F1中的雌雄鸡自由交配，产生的F2中雄鸡表现型有一种，雌鸡有两种

D．让F2中的雌雄芦花鸡交配，产生的F3中芦花鸡占3/4

【答案】C

【解析】由题干信息可知，控制鸡羽毛颜色的基因位于Z染色体上，且芦花对非芦花为显性；雄鸡的性染色体组成为ZZ，雌鸡的性染色体组成为ZW，所以显性性状在雄鸡中所占的比例较大，而隐性性状在雌鸡中所占的比例较大；假设控制芦花的基因为B，控制非芦花的基因为b，则F1中芦花雄鸡能产生ZB、Zb两种配子，非芦花雌鸡能产生Zb、W两种配子，雌雄配子随机结合，得到的F2雌雄鸡均有两种表现型；F2中芦花鸡的基因型为ZBW、ZBZb，杂交后代中只有ZbW为非芦花鸡，占1/2×1/2＝1/4，芦花鸡占3/4。

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