题目

育种专家在稻田中发现一株十分罕见的“一秆双穗”植株，经鉴定该变异性状是由基因突变引起的。下列叙述正确的是( ) A．这种现象是由显性基因突变成隐性基因引起的 B．该变异株自交可产生这种变异性状的纯合个体 C．观察细胞有丝分裂中期染色体形态可判断基因突变发生的位置 D．将该株水稻的花粉离体培养后即可获得稳定遗传的高产品系阅读理解阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。If the crust (外壳) of the earth were not pretty solid (坚固的), it would be shaking about and moving up and down frequently. However, there are places in the rocks of the earth's crust where it isn't strongly held together—where faults exist. Along the faults, one rock might push against another with great force. The energy is changed to vibration in the rocks, so they begin to shake and we have an earthquake!The most famous one in North America was the San Francisco earthquake of 1906. Seven hundred people died and property (财产) damage amounted to about $425,000,000.The greatest destruction came from the fires that followed the quake.One of the most famous earthquakes in Europe took place in Lisbon, Portugal, in 1755. The city was destroyed and at least thirty thousand people were killed. In 1908, in Calabria and Sicily, a quake killed about seventyfive thousand people. In 1915, in central Italy, hundreds of towns and villages were damaged and thirty thousand people were killed.Two great earthquakes that caused great damage in Asia took place in Tokyo, Japan, and in Gansu Province in China. The Tokyo quake of 1923 killed more than one hundred thousand people and destroyed the city and the city of Yokohama, too. The Chinese quake in 1920 covered more than three hundred square miles and killed about two hundred thousand people.（1）The first paragraph mainly tells us ________.A.where earthquakes happenB.how earthquakes happenC.the damage caused by earthquakesD.famous earthquakes in the world（2）The underlined word “vibration” in the first paragraph probably means “_______”.A.shakingB.forceC.energyD.losing（3）Which of the following earthquakes killed the most people?A.The San Francisco earthquake.B.The earthquake in Lisbon, Portugal.C.The earthquake in Calabria and Sicily.D.The earthquake in central Italy.（4）According to the passage, we can learn that ________.A.the earth's crust in Europe is weaker than that in other placesB.there were 75,000 people killed in the San Francisco earthquakeC.the city of Yokohama was not greatly influenced by the Tokyo quakeD.the fires following the San Francisco earthquake caused more damage than the earthquake did