問題詳情
12. In some plants, a yellow pigment is synthesized from a colorless precursor. In a cross between twoparental plants, one yellow and the other colorless, an F1 generation was produced that was all yellow.The F2 produced from the F1 had 1075 yellow, 275 pink and 90 colorless plants. What mode ofinheritance and phenotypic ratio do these results suggest?
(A) Incomplete dominance, 1:2:1 phenotype ratio
(B) Codominance, 9:6:1 phenotype ratio
(C) Dominant epistasis, 12:3:1 phenotype ratio
(D) Recessive epistasis, 9:3:4 phenotype ratio
參考答案
答案：C
難度：適中0.625
統計：A(0),B(1),C(10),D(0),E(0)
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上位作用的概念則是某一基因座上的基因表現型(phenotype)受另一個或多個基因座上的基因影響，也就是兩個獨立的遺傳基因對同一性狀發生作用。上位作用的典型例子是藍眼瑪莉(Blue-eyed Mary)的花色表現。一基因決定花是否有顏色(沒有顏色是指白色)，另一基因決定花色為藍色或洋紅色。當藍眼瑪莉含有兩個白色對偶基因，則無論後者基因表現為何，花色都為白色。由此可知，決定花是否有顏色的基因在基因交互作用中佔優勢，我們稱之為上位基因。