题干

春天,植物产生幼叶时要进行旺盛的细胞分裂,其细胞分裂方式和DNA复制的情况是(   )


A:无丝分裂,DNA不复制

B:减数分裂,DNA在细胞核中复制

C:有丝分裂,DNA在细胞核中复制

D:有丝分裂,细胞核、线粒体和叶绿体中DNA都复制

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答案(点此获取答案解析)

D

同类题1

阅读下文,完成小题。

                                                                                                                缺憾是现实的常态

        ①观赏自然美景,我们喜欢春日怒放的鲜花,喜欢秋夜皎洁的满月。欣赏艺术作品,我们喜欢匀称和谐的美,喜欢有情人终成眷属的大团圆结局。总之,我们喜欢圆满。但现实生活中,缺憾却往往是生活的常态,人走向成熟的标志之一就是学会正视缺憾。(甲)

        ②我们喜欢春日怒放的鲜花,但对一株花而言,一年里开放的日子却只有寥寥几天,在孕育花朵和花已凋谢的日子,我们往往会忘记这是一株花。觉得无花的花树给人一种萧条与落寞之感。多愁善感的林黛玉不是有“花谢花飞花满天,红消香断有谁怜”的慨叹吗?而萧条落寞的日子,正是孕育鲜花的过程,是必不可少的准备。胸怀豁达的诗人往往可以正视缺憾,甚至欣赏缺憾,龚自珍不是有“落红不是无情物,化作春泥更护花”的激赏吗?

        ③我们喜欢秋夜皎洁的满月,所以把农历八月十五日定为中秋节。佳节之际,因为共赏一轮明月,天涯之遥也给人咫尺之感。因此苏轼才用“但愿人长久,千里共婵娟”表达思念之情,也表达美好的祝愿。但月缺月圆、往复循环,是自然的规律,没有谁可以让月亮常圆不亏,而且一月之中缺多圆少。满月是美的,弯月也是美的。柳永的千古名句“今宵酒醒何处?杨柳岸晓风残月”,写的就是残月啊,以残月表达别后的相思,深情眷眷,感人至深。

        ④雕塑作品向来以匀称和谐为美,但断臂的维纳斯却是艺术品中的极品,受到世人的交口称赞。“断臂”是缺憾,但正是因为维纳斯双臂残缺,给了欣赏者无限的想象空间,使断臂的维纳斯反而更具神秘感,更具有神奇的艺术魅力。《牡丹亭》把爱情演绎到为爱可以“生而死,死而生”的境地,堪称爱情圆满结局的经典,使我们内心得到安慰。而有缺憾的爱情悲剧却可以震撼我们的心灵。《梁山伯与祝英台》的“历尽磨难真情在,天长地久不分开”传唱至今,《红楼梦》中“宝黛”缠绵悱恻,凄婉哀伤的爱情让人掬一把同情之泪。可见,缺憾也是一种美,一种带着伤感的美。

        ⑤自然界中缺憾是常态,艺术作品把缺憾当成了一种美,其实人生何尝没有缺憾呢?一份不理想的成绩单,一段不堪回首的往事,一份刻骨铭心却没有结局的爱情,一段执著却没有回报的努力……人生的痛就在这里。“久旱逢甘霖,他乡遇故知,洞房花烛夜,金榜题名时”都是瞬间的美丽,人生的圆满、幸福的巅峰偏偏不肯持续到永远;倒是缺憾太严谨,对任何人都会眷顾,一视同仁。但缺憾也让我们学会了追求,学会了进取,学会了珍惜来之不易的转瞬即逝的幸福。(乙)

        ⑥圆满是美好的理想,缺憾是现实的常态;圆满是纯净的美丽,缺憾是带着伤痛的美丽;圆满让我们满足、欣慰,缺憾带给我们叹惋和震撼。(丙)正是因为有了缺憾,有了正视缺憾的态度,才有了不懈的追求。有了持之以恒的努力,我们的人生才更丰富多彩,更韵味隽永。

同类题5

阅读下列短文,从下面每题的A、B、C、D四个选项中选出最佳答案。

Students in Suzanne Middle School have carried out many interesting surveys online. Here are some of them.

    Shopping online or in physical stores (实体商店)?

    Online shopping is changing how people buy things today. If you need new clothes but don't want to go out, your smartphone or computer is here to help you. However, according to a survey of 15,000 consumers between the age of 13 and 21 in 16 countries, most of them still prefer physical stores.

    Going offline easy or difficult?

    Technology has linked us in ways we never imagined. People spend more and more time on smartphones and computers but pay less attention to their children. Some US parents have felt the need to go offline. However, a recent survey showed that despite their best efforts, most of them couldn't stop using their smartphones and iPads.

Who makes you laugh the most?

     We all need a good laugh to cheer us up now and then. People are looking for different ways to get some fun in everyday life. Many like to watch comedies or read jokes. But a survey of 1,258 US teenagers found that 70 percent of them said it is their friends that make them laugh the most.

     Do you want to be a boss?

     We have read quite a lot of news about teenagers setting up

their own companies. Although most teenagers haven't started to do the same thing, it doesn't mean that they don't want to. According to a survey of 1500 US teenagers from the age of 13 to 18, 79 percent of them said they would like to have their own business.