题干

如图是某一年生自花传粉植物(2n=10)的某些基因在亲本染色体上的排列情况.该种植物的高度由三对等位基因B、b,F、f,G、g共同决定,显性基因具有增高效应,且增高效应都相同,还可以累加,即显性基因的个数与植株高度呈正相关.已知母本高60cm,父本高30cm.据此分析回答:

(1)图示细胞正处于____分裂时期,该时期此细胞核DNA分子有____ 个.

(2)F1的高度是____ cm,F1测交后代中高度为40cm的植株出现的比例为____ .

(3)多次实验结果表明,E基因存在显性纯合致死现象.如果让F1自交,得到的F2中杂合子Ee所占比例为____ .

(4)该种植物叶缘锯齿尖锐与光滑由两对等位基因控制,且只有基因都为隐性时才表现为叶缘光滑.已知其中一对是位于1、2号染色体上的D、d,请设计实验探究另一对等位基因A、a是否也位于1、2号染色体上(不考虑交叉互换).

第一步:选择图中的父本aadd和母本AADD杂交得到F1种子;

第二步:____ .

第三步:____ .

结果与结论:

①____ ,说明另一对等位基因A、a不位于1、2号染色体上.

②____ ,说明另一对等位基因A、a也位于1、2号染色体上.

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\u51cf\u6570\u7b2c\u4e00\u6b21,20,45,38,2

同类题1

阅读下面短文, 掌握其大意, 然后从各题所给的A、B、C、D四个选项中选出最佳选项。

    A boy thought that he was the most unhappy person in the world. In his opinion, he was unlucky because almost everything 1always happened to him. He wanted to find the 2 to happiness. He walked a long way and finally came to a beautiful palace. There, he met the king.

    After learning 3 the boy came, the king suggested that he should look around the palace and come back in two hours. “At the same time, I want you to hold this spoon 4 milk,” said the king. “As you walk around my palace, carry this spoon 5 without spilling the milk.”

    The boy kept his eyes fixed on the spoon and began to walk around the golden palace. After two hours, he came back to the king. “Well,” asked the king. “Did you 6 the wonderful paintings in my dining hall? Did you enjoy the colorful flowers in the garden?” The boy felt sorry because he saw 7.  He only paid attention to the milk.

    "Then go back and you can see the beauty of my world.” said the king. This time the boy saw all of the works of art on the walls. He saw the great gardens and hills all around. He had a great time 8 he was walking around the palace. When he 9, he described everything he saw.

     "But where is the milk?” asked the king. Looking down at the spoon he held, the boy saw the milk was gone. “Well, there is only one piece of 10 I can give you,” said the king. “The secret to happiness is to see all the beauty of the world and also keep an eye on the milk on the spoon.”