问题
选择题
下图表示某生物进行细胞分裂示意图,图中A、a、B代表不同的基因。以下说法正确的是

A.该细胞正处于减数分裂第Ⅱ次分裂后期、不可能发生过交叉互换
B.该生物的基因型是AaBB
C.该细胞形成时可能经过了一次基因突变
D.若该生物生存的环境对基因A生存比较有利,则aa型个体数量将在短时间内下降至零
答案
答案:C
下图表示某生物进行细胞分裂示意图,图中A、a、B代表不同的基因。以下说法正确的是
A.该细胞正处于减数分裂第Ⅱ次分裂后期、不可能发生过交叉互换
B.该生物的基因型是AaBB
C.该细胞形成时可能经过了一次基因突变
D.若该生物生存的环境对基因A生存比较有利,则aa型个体数量将在短时间内下降至零
答案:C
阅读理解。 | ||||||||||||
Bill has a brother Tom and a sister Lily. They have meals together every day. Bill and Tom like apples but Lily doesn't like them. Lily likes carrots, but Bill hates them. Tom likes fruits but he doesn't like vegetables. So their parents think they are not very healthy. | ||||||||||||
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