某种鱼的鳞片有4种表现型：单列鳞、野生型鳞、无鳞和散鳞，由位于两对同源染色体上的两对等位基因决定（用A，a，B，b表示），且BB对生物个体有致死作用。将无鳞鱼和纯合野生型鳞的鱼杂交，F1有两种表现

题干

某种鱼的鳞片有4种表现型：单列鳞、野生型鳞、无鳞和散鳞，由位于两对同源染色体上的两对等位基因决定（用A，a，B，b表示），且BB对生物个体有致死作用。将无鳞鱼和纯合野生型鳞的鱼杂交，F₁有两种表现型，野生型鳞的鱼占50%，单列鳞鱼占50%；选取F₁中的单列鳞鱼进行互交，其后代中有上述4种表现型，这4种表现型的比例为6：3：2：1，则F₁的亲本基因型组合是（　　）

A：Aabb×AAbb

B：aaBb×aabb

C：aaBb×AAbb

D：AaBb×AAbb

上一题下一题 0.0难度选择题更新时间:2016-10-21 02:45:54

答案(点此获取答案解析）

C

同类题2

阅读理解A
I'm Linda．I can't find my keys．I lost them this morning．There is a Lost and Found box in our classroom．My keys may (可能)be in the box．
Oh, there are many things in the box．This is a pencil box．What color is it? It's yellow．That is a white eraser．And what's that? It is a watch．A picture of a CD is on it．It's Sara's．Wow! I find my keys．One is to my classroom，and the other (另一个)is to my house．That green cup is Jack's．This baseball is his，too．I will(将)ask him to take his things．Three rulers, two pencils and two nice pens are also in the box．Whose are they? I don't know．
根据材料内容判断正误。

题干

答案(点此获取答案解析）

同类题1

同类题2

同类题3

同类题4

同类题5