题干

为获得纯合高蔓抗病番茄植株,采用了下图所示的方法:图中两对相对性状独立遗传。据图分析,不正确的是                                                               (   )

A:过程①的自交代数越多,纯合高蔓抗病植株的比例越高

B:过程②可以取任一植株的适宜花药作培养材料

C:过程③包括脱分化和再分化两个过程

D:图中筛选过程不改变抗病基因频率

上一题 下一题 0.0难度 选择题 更新时间:2018-04-10 04:07:09

答案(点此获取答案解析)

D

同类题5

据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    My sister Alli and I have been trying to get people to stop dropping cigarette butts (烟蒂) for seven years.

    One day, we were walking in our hometown and saw hundreds of cigarette butts on the ground.____

    They made the town look so ugly that we decided to start a group to make people stop dropping butts. We called it "No Butts About It!"

    At first, we drew pictures with "The Earth Is Not Your Ashtray (烟灰缸) " written on them. We put the pictures around our hometown--in parks, by beaches, and along roads.

    We wanted to make people understand that dropping butts does harm to the environment. Most smokers don't think that dropping butts harms the earth.____

    Later, we wrote to companies and asked them for money to help us. We used the money to buy ashtrays to give smokers.

    We wanted smokers to carry the ashtrays with them so they didn't have to drop butts.

    At the moment, we are trying to get cigarette companies to put an ashtray in each pack of cigarettes.____Many people have started to join our group since it began.____And there are even groups in England, Australia and India !

    Many newspapers have written about my sister and I over the last seven years. And we have won many prizes for our good work.

    ____We just want to make the earth a better and cleaner place for animals, plants and people.

    One day it will be.

A. My sister and I set up a "No Butts About It" group.

B. But we are not interested in prizes.

C. Today there are 45 other "No Butts About It" groups in America.

D. They made the ground dirty.

E. But it does! All rubbish does.

F. Many smokers like to drop butts here and there.

G. Some companies would like to do it.