题目

下列有关细胞结构和功能的叙述，正确的是（ ）A. 具有双层膜结构的细胞器均含有DNA分子B. 真核细胞有DNA，原核细胞无 C. 蓝藻因为有叶绿体呈现绿色D. 在同一个体内，具有相同细胞器的细胞其功能大致是相同的 答案：【答案】A【解析】本题是对真核细胞与原核细胞的区别、线粒体和叶绿体的结构、细胞分化的实质的综合性考查。具有双层膜结构的细胞器是线粒体和叶绿体，二者都含有DNA，A正确；真核细胞与原核细胞的遗传物质都是DNA，都具有DNA，B错误；蓝藻是原核细胞，只有核糖体一种细胞器，不含有叶绿体， 阅读理解。     根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。      Have you ever seen any students whose trousers hang so low that you can see their underwear? What do you think of that? Fashionable? Some of today's teenagers are big fans of such a look.   1        The headmaster of a school in central Italy has asked students to stop wearing low-rise jeans that expose underwear and parts of the body. His request came after a class trip, when he saw one boy's baggy trousers slide to his feet.     2   But in Italy, a nation that takes fashion very seriously, the suggestion caused a debate among parents,teachers and students. The issue is whether the headmaster's request will limit students' freedom- or whether dress in Italian schools is too casual.       3    ."We do not want to kick fashion out," the headmaster explained, "but extrems (极端) of fashionlike this are not right in school." Many other schools have now requested that their students also stop wearing such trousers.       4   . Ludovica Gaudio, 14, wore extremely low trousers exposing orange underwear in class. It was cold, so she wore a matching orange scarf.  5   "I don't really feel comfortable in those sort of jeans," said Sarah Lattanzi, "in winter, when dressed like that, it's quite cold and I am afraid my stomach will ache." A. But recently this trend has been at the center of an argument in Italian middle schools.B. A parents' group praised the move in favor of good taste, while others advised schools      to stop worrying about fashion and fix up old school buildings.C. He pointed out that this way of dressing is not suitable for school.D. Most students have simply ignored the requestE. Another 14-year-old said she would probably respect the request, simply for practical reasonsF. Let us see that Italian students react differently to schools' requests G. Schools should pay attention to things more important than students' clothes