题干

绿色荧光标记的X染色体DNA探针(X探针),仅能与细胞内的X染色体DNA的一段特定序列发生碱基互补配对,并使该处呈现绿色荧光亮点.同理,红色荧光标记的Y染色体DNA探针(Y探针)可使Y染色体呈现一个红色荧光亮点.同时用这两种探针检测体细胞,可诊断性染色体数目是否存在异常.医院对某夫妇及其流产胎儿的体细胞进行检测,结果如图所示.下列分析不正确的是(    )

A:X染色体DNA上必定有一段与X探针相同的碱基序列

B:据图分析可知妻子患性染色体数目异常遗传病

C:流产胎儿染色体异常原因可能与来自父亲的精子异常有关

D:该夫妇选择生女儿可避免性染色体数目异常疾病的发生

上一题 下一题 0.0难度 选择题 更新时间:2018-09-14 10:44:03

答案(点此获取答案解析)

D

同类题5

阅读下面短文,从短文后各题所给的四个选项()A、B、C和D)中,选出可以填入空白处的最佳选项。

    I sat down at my desk and tried to focus on my studies. In just seven more days, finals would be over and all the students in my college 1 would be leaving to   go home-2 me. I would be moving 3 to another dormitory for the Christmas break.

    I had no 4. I was a student from Pennsylvania attending college in Utah and my family of ten couldn't 5 to pay for my ticket home. The only 6 I was even able to attend college was that I had received several scholarships.

    I started at the white snow dancing through the air. This would be my 7 Christmas away from home. I felt so 8 that I could weep. 9 I swallowed down the ache that was rising in my throat, my phone rang suddenly. I reached over and picked it 10.

    “Hello?”

    “Hi, Teddi. This is Elsie.” What was my boss from high school grocery job 11 me for? “All the workers here 12 that you weren't able to make it home this year.13 we bought you a ticket. You're coming home!”

    I screamed.

    Fifteen minutes later I was off the14and jumping up and down for 15. Neighbors came over to see what the 16 was all about.

    “I'm going home for Christmas! My17 at my high school job bought me a ticket!” I told them.

    Christmas 18, I was awoken by laughs and screams of joy. The smell of roasting turkey and the wrapping paper(包装纸)that grew higher and higher filled me with love and 19. The kindness of some special fiends 20 me to have the best Christmas ever.