玉米胚乳蛋白质层颜色由位于两对同源染色体上的A、a和R、r两对基因共同作用而决定。A、a控制玉米基本色泽的有无，A对a为显性；R、r分别控制玉米胚乳蛋白质层颜色，R对r为显性．分别控制紫色和红色：当A基因存在时，R和r基因的作用都可表现，分别使玉米胚乳蛋白质层出现紫色和红色，当只有a基因存在时(无A基因)，不允许其他色泽基因起作用。蛋白质层呈现白色。
(1)玉米胚乳蛋白质层颜色的遗传遵循_____：该遗传现象说明，生物的性状表现与基因之间不是简单的_____的关系。
(2)现有红色蛋白质层植株与白色蛋白质层植株杂交，后代全为紫色蛋白质层个体，若亲代都为纯合子，则基因型为_____；若将F1自交，则F2的表现型及比例为_____。
正确答案及解析
正确答案
解析
(1)自由组合定律；线性
(2)AArr和aaRR；白色：紫色：红色=4：9：3
(1)玉米胚乳蛋白质层颜色的遗传遵循自由组合定律；由于两对基因共同控制着蛋白质层颜色，因此性状表现与基因之间不是简单的一一对应的线性关系。
(2)由题意可知红色蛋白质层植株A_rr与白色蛋白质层植株aa杂交，后代全为紫色蛋白质层个体A_R_，并且亲代都是纯合子，因此亲代的基因型分别是AArr和aaRR，后代基因型为AaRr。若将AaRrA交，后代表现型及比例为白色(aa_)：紫色(A_R_)：红色(A_rr)=4：9：3。
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