题目

下列有关基因、DNA和染色体说法中正确的是（ ）A．一个DNA含有一个基因B．一条染色体由一个DNA和一个蛋白质组成C．基因是具有遗传效应的DNA片段D．每条染色体上有很多个DNA分子 答案：【答案】C【解析】试题分析：染色体由蛋白质和DNA组成，基因是DNA分子上的一个具有遗传信息的片段，DNA分子很长，基因有规律地排列在DNA分子上，每条DNA分子上有很多个基因，A错误；染色体的化学成分主要是DNA和蛋白质，一条染色体由一个DNA和若干个蛋白质组成，B错误；基因位于染色体上，基因是D用所给单词的适当形式填空 。  1. I    __(tell) you when he  __  (call) me tomorrow.    2. If it    _   (not rain) next Sunday, we  _     (go) for a picnic.3. As soon as he arrives home, I     _  (let) you know.4. She        (not go ) to bed until 11 o'clock last night. 5. We won't go to his party unless he_      (invite) us.6. He worked hard enough        (make) more money. 7. We         (not leave) here until you come back.8. He worked very hard, so he       _ (pass)the test.9. The more you read,                    (much) you will know.10. Though we worked hard at English,  we        (not pass)the final exam.