问题 单项选择题

如果通过转基因技术,成功改造了某血友病女性的造血干细胞,使其凝血功能全部恢复正常。当她与正常男性结婚,婚后所生子女的表现型为()

A.儿子全部正常,女儿全部有病

B.儿子、女儿中各一半正常

C.儿子全部有病,女儿全部正常

D.儿子、女儿全部正常

答案

参考答案:C

解析:

女性的卵细胞是由卵原细胞分裂而来,改造造血干细胞但卵原细胞的基因并未变化.血友病为伴X染色体隐性遗传.根据题意写出双亲基因型:父亲XHY×XhXh,可知,子代中所有的女儿基因型都是XHXh为正常携带者,儿子基因型都是XhY,为患者.

考点:本题考查伴性遗传.

点评:生殖细胞中遗传物质的变化才会遗传给后代

不定项选择
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My problems started after I went to a boar ding school. I was only 14, and at first I missed my family a lot. I often called them and cried on the phone. But after two weeks, I found I enjoyed being with my classmates at school.

I had many friends who were boys. I thought of them as my best friends - but only friends. I never guessed my friendships with boys would become a problem.

Then, three months later, my friends told me that some teachers and girls said I was hanging out with boys all day long in order to get attention from them. Seven months after that, the head teacher Mr. Wang asked the class to choose some students to join the Student Union. I thought I could win for I was doing well in school. I'd already won prizes for the best math and English exams. A week later, the list came out and it didn't include me. I was sad.

Mr. Wang came to me and sai d, "Don't be sad. I know you're excellent! Maybe

you're a little distant from the girls in our class. They don't know much about you, so some of them didn't choose you. It doesn't matter. Do your best to get along well with everyone and I think you'll make it next time."

小题1:What was the writer's problem when she first entered the boarding school?

A.She didn't like her new school.

B.She didn't get along well with her classmates.

C.She missed her family very m uch.

D.She didn't like her new teacher.小题2:Many of the writer's friends in her new school were _______.

A.teachers

B.boys

C.girls

D.women小题3:Why did the writer fail to join the Student Union?

A.Her teachers didn't like her.

B.She was a poor student.

C.Some girls didn't choose her.

D.She likes showing off herself.小题4:Which of the following is NOT true, according to the passage?

A.The writer won prizes for the best science and English exams.

B.The writer didn't realize that her friendships with boys would cause problems.

C.The writer was sad because she failed to join the Student Union.

D.The teacher thought she was an excellent student