题干

下列有关双链DNA复制的叙述中,正确的是(    )

A:DNA分子复制发生于有丝分裂间期和减数第一次分裂前的间期

B:复制过程遵循碱基互补配对原则,即A与U配对,G与C配对

C:DNA分子复制过程是先完全解旋然后开始复制

D:解旋在细胞核中进行,复制在细胞质中进行

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答案(点此获取答案解析)

A

同类题2

    One afternoon, my son came home from school and asked me, “Are all people the same even if their skin color is different?” I thought for a moment, then I said, “I'll explain. Let's go to a fruit store first. I have something interesting to show you.”
At the store, I told him that we needed to buy apples. And we bought some red apples, green apples and yellow apples.
   After we got home, I told Adam, “It’s time to answer your question.” I put one of each type of apple on the table: first a red apple, followed by a green apple and then a yellow apple. Then I looked at Adam, who was sitting on the other side of the table.
   “Adam, people are just like apples. They come in different colors, shapes and sizes. See, some may not even look as delicious as others.” As I was talking, Adam was examining each one carefully.
   Then, I took each of the apples and peeled them, placing them back on the table, but in a different place.“OK, Adam, tell me which one is the red apple, the green apple and the yellow apple.”He said, “I can’t tell. They all look the same now.”“Take a bite(一口) of each one. See if that helps you tell which one is which.”He took big bites, and then a huge smile came across his face. “People are just like apples! They are all different, but if you take off the outside, they’re pretty much the same on the inside.”“Right,” I agreed. “Just like everyone has their own features but they are nearly the same.”
   He completely got it. I didn’t need to say or do anything else.
   Now, when I eat an apple, it tastes a little sweeter than before. What perfect fruit it is!