题干

下列有关基因突变和基因重组的叙述,正确的是(     )

A:基因突变一定引起生物体表现型改变

B:基因重组是生物可遗传变异的根本来源

C:基因突变是指基因的碱基对增添、缺失或替换

D:基因重组可以产生新的基因

上一题 下一题 0.0难度 选择题 更新时间:2018-06-29 11:37:33

答案(点此获取答案解析)

C

同类题5

阅读理解

    International Children's Day is coming up on June 1st. Here we have chosen some films from around the world that are most worthy for children to see.

    E, T. the Extra-Terrestrial (1982)

    Director: Steven Spielberg

    Country: United States of America

    Storyline: A group of aliens are visiting the Earth at night. But one of the visitors from space is left behind and finds himself all alone on a very strange planet. Fortunately, he meets Elliot, a lonely boy himself, and slowly makes friends with Elliot's older brother Michael, his sister Gertie. Meanwhile government officers work day and night to track down the little alien. Elliot and others try their best to help the alien go home.

    Children of Heaven (1997)

    Director: Majid Majidi

    Country: Iran

    Storyline: Ali takes his little sister Zahra's shoes to the shoemaker to be repaired but loses them on the way home. There is no money to buy another pair. Ali makes a plan to share his shoes: Zahra will wear them in the morning and hand them to Ali at midday so he can attend school classes. Ali then enters a children's racing competition in hopes of receiving the third prize, a new pair of shoes.

    Kes (1969)

    Director: Ken Loach

    Country: United Kingdom

    Storyline: Bullied (欺凌) at school and getting little attention at home by his mother and older brother, Billy Casper, a 15-year-old boy from a working-class family, finds peace in his pet falcon (猎隼), Kes. With encouragement from his English teacher, Billy eventually discovers a positive purpose to his unfortunate life, until some bad thing comes.