题干

如图是用玉米的①②两个品种,分别培育④⑤⑥⑦四个新品种的过程,A,a和B,b表示两对等位基因,且分别位于两对同源染色体上,则下列说法错误的是(  )


A:培育生产用品种④的途径中,Ⅰ→Ⅲ→Ⅴ比Ⅰ→Ⅱ途径所用时间短

B:Ⅲ过程常用的方法是花药离体培养

C:Ⅴ过程与Ⅵ过程的育种原理相同

D:Ⅳ、Ⅵ过程中的变异发生于相同的细胞分裂期

上一题 下一题 0.0难度 选择题 更新时间:2017-06-30 12:05:59

答案(点此获取答案解析)

D

同类题5

配对阅读:左栏是5个中学生遇到的问题,右栏是某报社编辑提供的7个建议.请将这5个问题与其相对应的建议配对起来.其中有2项是多余的。

Students' problems

Suggestions from Editors

①I am not allowed to hang out with friends at all. My parents want me to study all the time at home. I feel unhappy. ____  

②I am too shy to speak in front of my classmates. They always laugh loudly when I am answering teachers' questions. I 'm frustrated. ____  

③My mother is a doctor. She is too busy with her work to spend the weekends with me. It seems that she doesn't care me at all. I feel lonely. ____  

④A senior high school student asks me to give him 100 yuan every week without telling others. I am frightened. So I don't want to go to school now. ____  

⑤I think I work harder than others but I get bad grades. Am I too stupid? ____  

A. Nobody is born-stupid. Maybe you haven't got right ways of study yet. Ask the teachers or classmates for help if you have any questions.

B. If you feel unhappy, go to have a good sleep and you will forget everything unhappy.

C. Don't be afraid. You should tell your parents or teachers at once. Don't go out alone then.

D. Your classmates may not laugh at you. If you don't like their laughter, you should talk to them about your feelings. They might understand you. And you had better be more easygoing and be their friend. You won't feel frustrated if your friends laugh.

E. Let your parents know your friends are nice. You learn a lot from them as well as having fun with them. You study with them outsides, too

F. Tell your mother you need her company sometimes. Also you could do some chores with your mother so she can finish her work quickly. Try to understand your mother and let her understand you, too.

G. You could invite your friends to play with you at home. It's fun to play in doors, too.