A.They have two children already. B.Mrs. Smith wishes to have children, but her husband doesn't. C.They will start a family as soon as they get married. D.They don't want children for the time being.
【简答题】玉米的紫株和绿株由 6 号染色体上一对等位基因( H , h )控制,紫株对绿株为显性。纯合紫株 A 经 X 射线照射后再与绿株杂交,子代出现少数绿株(绿株 B )。为研究绿株 B 出现的原因,让绿株 B 与正常纯合的紫株 C 杂交得 F 1 , F 1 自交得 F 2 。请回答: ( 1 )假设一: X 射线照射导致紫株 A 发生了基因突变。若此假设成立,则 F 1 的基因型为 ________...