题目

在非洲人群中，每10000人中有1个人患囊性纤维原性瘤，该病属常染色体遗传。一对健康的夫妇生有一患病孩子。此后该妇女与另一名健康男性再婚，他们若生孩子，患此病的几率是（   ）         A.1/25     B.1/50           C.1/100         D.1/200     答案：D 解析: “一对健康的夫妇生有一患病孩子”由此可以判断囊性纤维原性瘤为常染色体隐性遗传病，患者基因型为aa，人群中aa的基因频率为1/10000，由公式（p+q）2=p2+2pq+q2可计算出a的基因频率为1/100，则A的基因频率为1-1/100=99/100，Aa的基因型频率为2×1/100×99/100≈1/50，该妇女的基因型为Aa，只有与Aa的个体婚 缺词填空，先通读下面的短文，掌握其大意，然后根据短文内容和所给首字母，在空格内填入一个适当的词，使短文意思完整。所填单词在题后横线上必须完整写出。 　　Earth Hour started in Sydney o　　1　　 March 31, 2007．M　　2　　 than two million homes and Businesses turned off their lights for an hour．A year l　　3　　 , in 2008, Earth Hour became the world's activity and was supported by m　　4　　 of people from thirty-five countries．In 2009, over two thousand cities in the world took　part in it, and Earth Hour came to China．The purpose of the activity is to save energy and improve　climate．Earth Hour has b　　5　　 some new changes to our lives． 　　We may have different ways to spend the hour．For e　　6　　, we can go to school on foot or b　　7　　 bike, plant more trees, use water more than once, never l　　8　　 the lights on when we are not at home．Try to make full use of paper by using b　　9　　 sides．Earth Hour is a call for us to work together for a bright f　　10　　．It is also a message of hope and action．Everyone can make a difference．The improvement(改善)of our environment n　　11　　 everyone's efforts(努力)．Come on! J　　12　　 us in Earth Hour 2010!