题干

某植物茎秆有短节与长节,叶形有皱缩叶与正常叶,叶脉色有绿色和褐色,茎秆有甜与不甜.下面是科研人员用该植物进行的两个实验(其中控制茎秆节的长度的基因用A和a表示,控制叶形的基因用B和b表示).请回答下列问题.
上一题 下一题 0.0难度 选择题 更新时间:2018-04-12 04:56:02

答案(点此获取答案解析)

同类题2

阅读理解

    What's going on under Liverpool?
A Rainy Day in Liverpool

    Dark clouds appear over the River Mersey and a cold wind is blowing. A few rain drops are beginning to fall. We're in the famous city of Liverpool and we're going to spend this rainy day in the Williamson Tunnels.
  An Interesting Life Story

    Joseph Williamson was born into a poor family in 1769,but left home and went to work for a tobacco company aged 11. He began at the bottom, and finally became head of the business.

 An Unsolved Mystery

    Nobody knows why Williamson dug tunnels under most of Liverpool, but many think it was to create jobs. Perhaps half of Liverpool's population worked for him. The industry of war had made enormous amounts of money, but now Liverpool was in a terrible financial situation.

 The King of Edge Hill

    I went on a guided tour starting close to where his empire began in Edge Hill. In the tunnels, the steps leading from rooms below ground to those buildings, which no longer exist, seem particularly ghostly.

Incredible Engineering

    We go into the Double Tunnel. It's just been discovered that it's actually a triple tunnel - but nobody knows why the three tunnels were built on top of each other.

    We finish the tour and decide we'll have a coffee in the Williamson Tunnels Cafe Bar. There, I notice lots of flyers for bands and theater groups that are coming to play there.

Why Liverpool?

    Apart from the obvious attractions like the football clubs, or anything to do with the Beatles, Liverpool has a lot to offer. Princes Park and Croxteth Park were royal hunting grounds and the trees are 200 years old. Renshaw Street displays are an unusual mix of architecture styles. The nightlife is exciting. If you want to experience a part of the British Isles with a character entirely different from London, you should definitely come to Liverpool.