问题 填空题 案例分析题

基因工程是在现代生物学、化学和工程学基础上建立和发展起来的,并有赖于微生物学理论和技术的发展运用。基因工程基本操作流程如右图所示,请据图回答:

不同种生物之间的基因能拼接成功,从分子结构角度分析是因为:(),目的基因在不同的生物细胞中能正确表达,说明了不同生物共用()。

答案

参考答案:不同生物的DNA分子都为双螺旋结构;不同生物共用一套遗传密码

解析:不同种生物的DNA间所以能够进行拼接,在于不同生物的DNA都具有共同的双螺结构,目的基因能够在不同的生物体中得以表达,缘于在表达过程中生物体所用的遗传密码是相同的。

阅读理解

阅读理解。

     How often one hears that children wishing they were grown-ups and old people wishing they were

young again!  Each age has its pleasures and pains, and the happiest person is the one who enjoys what

each age gives him without wasting his time in useless regrets.

     Childhood is a time when there are few responsibilities to make life difficult. lf a child has good parents, he is fed, looked after and loved, whatever he may do. It is impossible that he will ever again in his life be

given so much without having to do anything in return. In addition, life is always presenting new things to

the child-things that have lost their interest for older people because they are too well-known. But a child

has his parents. He is not so free to do what he wishes to do; he is continually being told not to do things

or being punished for what he has done wrong.

      When the young man starts to earn his own living, he can no longer expect others to pay for his food,

his clothes, and his room. But he has to work if he wants to live comfortably. If he spends most'of his time playing about in the way that he used to as a child. he will go hungry.  And if he breaks the laws of society as he used to break the laws of his parents, he may go to prison. If, however, he works hard, keeps out

of trouble and has good health, he can have the great happiness of building up for himself his own position

in society.

1. According to the second paragraph, the writer thinks that_______.

A. life for a child is comparatively easy

B. a child is always loved whatever he does

C. if much is given to a child, he must do something in return

2. After a child grows up, he_______ .

A. will have little time playing

B. should be able to take care of himself

C. can still ask for help in time of trouble

3. Which of the following statements is NOT true according to the passage?

A. People are often satisfied with their life.

B. Life is less interesting for old people.

C. Adults are free to do what they want to do_______.

4. he underlined word "responsibilities" in the second paragraph means_______.

A. duties

B. jobs

C. suggestions

5. The main idea of the passage is_______.

A. life is not enjoyable since each age has some pains

B. young men can have the greatest happiness if they work hard

C. one is the happiest if he can make good use of each age in his life

单项选择题