问题 读图填空题

下图为大肠杆菌的DNA片段示意图。请据图回答下列问题:

(1)图中⑤中文名是_________,④的中文全称是__________。

(2)含有200个碱基的某DNA片段中碱基间的氢键共有260个。请计算:

①该DNA片段中C和G共_________对。

②该片段复制2次,共需原料脱氧核苷酸______个。

(3)假定大肠杆菌只含14N的DNA的相对分子质量为a;只含15N的DNA的相对分子质量为b。现将只含15N的DNA培养到含14N的培养基中,子一代DNA的平均相对分子质量为______,子二代DNA的平均相对分子质量为_________。

答案

(1)腺嘌呤;胞嘧啶脱氧核苷酸

(2)①60;②600

(3)(a+b)/2;(3a+b)/4

阅读理解

阅读理解。

                                              The Loss of Innocence(纯真)

     Innocence is such a precious gift. It's explained as freedom from guilt or wrong doing. Just

imagine never having to worry about anything and having a guilt-free mind. Some people wish

to save this kind of innocence from being lost from childhood to adulthood.

     What would the world be like if innocence were never lost? One way it would benefit

humanity is the lack of hatred (仇恨) among the world. During youth, there may be an occasional

argument, even a little physical fight, but nothing like firing a handgun at a fellow human being.

And children are blind towards the racial differences of others. A kid will hang out with any

other kid. It is the lack of innocence and the ignorance we learn from adults that influence

children otherwise. Another benefit is the constant desire for fun and adventure. With very little

if any time at all for fun, the adventurous mind is lost in time with the responsibilities placed upon

adults. If innocence were kept alive, these ambitions would never depart from our lives.

     However, other people actually hate the idea of innocence lasting for ever. They feel that the

lack of organization and mental power of those with innocence would cause extremely destructive

consequences to society in general. A large number of individuals would never have the urge to

learn, work, and act upon the necessary needs for humanity to survive. Without a proper

education which is usually provided by those who no longer live in a world of innocence, people

would not have the desire to succeed, get a good job in life, or provide income for their families,

which

     would hurt the lives of children.

     The lack of a good education and career would also harm the economy. As long as

innocence is kept alive, no one would be terribly angry at the lack of effort people put out in

the workplace, resulting in a strong decline(减少) in production and quality of needed goods.

     Maybe it is wrong in wanting to save innocence. It sure is a nice thought, though. Perhaps

innocence was meant to be lost. It was god's will to make things the way they are, and there

is a good purpose for everything. All that remains to be said about innocence is to enjoy it while

it lasts.

1. The author believes that the loss of innocence in adulthood should be______.

A. avoided

B. criticized

C. accepted

D. encouraged

2. Lifelong innocence would be beneficial to society in that__________.

A. proper education would be provided

B. there would be no racial discrimination

C. there would be more happy families

D. people would realize their childhood dreams

3. According to the author, people with innocence can hurt the economy with their lack of____ .

A. motivational will

B. mental ability

C. adventurous ambitions

D. needed goods

4. Which of the following shows the structure of the passage?_____

CP:Central PointP:PointSp:(次要点)C:Conclusion

写作题