题干

科恩伯格(Kornberg)曾经以噬菌体为引子,用四种脱氧核苷酸为原料,加入适量ATP和DNA聚合酶,在试管中把游离的脱氧核苷酸合成了噬菌体DNA,这种半人工合成的DNA也能够在寄生细菌体内繁殖.请回答下列问题:

(1)该实验说明的问题是____ .

(2)加入ATP的目的是____ ,说明该过程需要____ .

(3)加入DNA聚合酶的目的是____ 

(4)若DNA是在细菌细胞内合成,则其场所是____ ;若在真菌细胞内合成,其场所可能是____;若再高等植物叶肉细胞内合成,其场所可能是____ 、____ 、____ .

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答案(点此获取答案解析)

\u5728\u4e00\u5b9a\u6761\u4ef6\u4e0b\uff0cDNA \u5177\u6709\u81ea\u6211\u590d\u5236\u529f\u80fd,\u4e3aDNA \u590d\u5236\u63d0\u4f9b\u80fd\u91cf,\u4e00\u4e2a\u8017\u80fd\u7684\u8fc7\u7a0b,\u4fc3\u8fdbDNA \u65b0\u94fe\u7684\u5408\u6210,\u539f\u6838\

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    When it comes to the benefit of volunteering, a lot of people think it's all about the warm feeling after helping someone. ____As is known, charity work requires a wide variety of people to do a wide variety of things for everything to work. It means that there are some surprising benefits for volunteers. For example, volunteering:

    Teaches you new skills.

    From helping making websites to teaching immigrant kids your native language, or to arranging events for charity, volunteering can really be almost anything. It means that when you get involved charity work, a lot of the time you will face challenges. ____

    Can teach you what truly matters.

    It's a great way to find new perspectives(角度)on life. When you've been at it for a while, you just might find yourself re-evaluating your advantages.____ One of my friends went from wanting U be a lawyer to discovering a true passion for teaching

    ____

    Maybe it is not surprising, but what might surprise you is how genuine these friends are. Some oi my long-term friends are people I've met through volunteering. I'm not that kind of guy that makes friends purely for connections, but sometimes it's very convenient to have a broad network.

    Summed up in one line: volunteering helps you grow. ____ You meet a wide variety of people who don't have a lot in common with. You learn to get along with people involved in many different walks in life. You learn to know what you are to do. So if you've ever considered volunteering, what are you waiting for?

A. You might even decide on a completely new path to take in life.

B. Helps you make new friends

C. As it turns out, that's far from the only benefit.

D. Volunteering helps you look outside yourself and your problems.

E. Through overcoming the challenges, you learn completely new skills.

F. Not only as a person, but it helps you develop your skill as well.

G. Can help improve social skills