题目

科学家对人群某一基因位点进行调查，发现等位基因A对基因a为显性，以下说法正确的是( )A.AA与Aa表现型相同 B.Aa与aa表现型一定相同C.基因A由基因a突变产生 D.纯合体aa一定会导致遗传病 答案：【答案】A【解析】AB、由于A是显性，所以AA和Aa都表现出显性，aa表现出隐性，A正确；B错误；CD、由于本题没有告知A和a谁是致病基因，所以CD无法判断，不符合题意；故选A。阅读理解 　　I study at No. 12 Middle School. My home is far from my school. I get up early every morning. I ride my bike to school. I have lunch at school. 　　Sometimes I buy some bread and drinks for my lunch in the shop near our school. My father works in a factory behind my school. He goes to work by bus(乘车). He leaves his factory at 5:00 p.m. and we go home together. 1．What do I do? [　　] A．A farmerB．A worker C．A teacherD．A student 2．I have ________ in my school. [　　] A．breadB．supper C．lunchD．breakfast 3．There's not a ________ near my school. [　　] A．bus stopB．shop C．factoryD．farm 4．My father ________ by bus. [　　] A．goes to the townB．leaves work C．goes to workD．goes to school 5．I go home with ________ every afternoon. [　　] A．my motherB．my father C．my friendsD．my brother