题干

有一对基因型为XBXb、XbY的夫妇,生了一个基因型为XBXbY的孩子。如果这对夫妇中只有一方在减数分裂时发生异常,且没有基因突变发生,则下列哪些原因可以造成上述结果?
①精原细胞减数第一分裂正常、减数第二分裂异常;
② 精原细胞减数第一分裂异常、减数第二分裂正常;
③ 卵原细胞减数第一分裂正常、减数第二分裂异常;
④ 卵原细胞减数第一分裂异常、减数第二分裂正常。

A:①③

B:①④

C:②③

D:②④

上一题 下一题 0.0难度 选择题 更新时间:2018-09-07 09:06:54

答案(点此获取答案解析)

D

同类题3

    It's cool, it's hot, and everyone is doing it. People talk about it often, and friends tell other friends how good they look. Sound like a fashion? In fact, it's another trend (流行趋势)"blog". What's a blog? A blog is a personal online diary. The word "blogger" means a person who writes diaries onlin
    Many bloggers are teenagers who log (进入) onto websites to discuss anything in their lives. Many of today's teenagers are not afraid to openly discuss everything in their lives. Teenagers complain about parents and homework. They share diaries, post songs from the latest bands (乐队) and show pictures of theirs. They write their own poems, say something about their girlfriends or boyfriends and complain to each other or offer support. But mostly they just write down what they do every day.
    However, many parents are worried about these young bloggers. Parents see the kids talking about how they got drunk last weekend and how they don't like studying. They are using language that is surprising to their parents. Besides hearing from their friends, teen bloggers also get messages from strangers. Most of the time, it’s older men asking to meet teenage girls. "These strange men are dangerous for my kids. They sometimes teach my kids bad words," said Cara Cabral, a mother of two.
    Many teenagers and young adults know it's not safe to use blogs on the Internet. They know they are putting information about themselves in a place they can be seen by anyone. But teenagers are unwilling to give up these new communication tools that have become a way of life for many of them.