题干

下图为人体细胞的分裂、分化、衰老和死亡过程的示意图,图中①—⑥为各个时期的细胞,a—c表示细胞所进行的生理过程。据图分析,下列叙述正确助是(   )

A:与①相比,②的表面积与体积的比值增大,与外界环境进行物质交换的能力增强

B:⑤与⑥的基因型相同,蛋白质的种类也相同

C:若⑤⑥已失去分裂能力,则其细胞核内遗传信息的流动方向为DNA→RNA→蛋白质

D:细胞的衰老与死亡就会引起人体的衰老与死亡

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C

同类题5

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Tom and Steve were twin brothers. Tom loved to play basketball. But Steve loved to read books. One day Tom was playing basketball    21  he fell and broke his leg. When they took him to the hospital, the doctor said he wouldn’t be able to play for six months. Steve went    22  him to and brought him books on basketball. At first Tom wasn’t going to read them. Then he began to read them and 23 that there were ways he could play basketball better. He began to think that books weren’t    24  .

    When Tom’s leg started getting better, Steve would help him by going for walks with him.  25 Tom’s doctor said he could start playing basketball again. Then Tom showed Steve how to toss(投)for baskets. Steve found that he enjoyed it.

    Then Tom was ready to   26   the basketball games. Steve went to watch the games and enjoyed himself. They then    27   practiced basketball and read books together.

    So you can see, when    28    happens, something good may also happen. Steve showed Tom about books and Tom showed Steve about basketball.

So you can also   29   showing others something that you like to do and they can show you something that they like to do. 30 you can find new things to do.

21A. until              B. when            C. after           D. where

22A. on seeing          B. to call            C. to visit         D.to look

23A. saw              B. looked            C. read           D. found

24A. good             B. bad              C. better           D. worse

25A. But              B. However          C. Finally         D. So

26A. take              B. win              C. lose            D. join in

27A. always            B. never            C. seldom          D. much

28A. anything good      B. something nice     C. something bad   D. anything wrong

29A. try               B. practice           C. enjoy          D. like

30A . On the way       B. By the way        C. In a way       D. In this way