问题 解答题

如图是植物根尖模式图,有关叙述正确的是(  )

A.①是吸收水分和无机盐的主要部位

B.②处的细胞具有较强的分裂能力

C.③处的细胞没有细胞壁

D.④具有保护作用,主要由导管细胞构成

答案

根尖是指从根的顶端到生有根毛的一段.它的结构从顶端依次是④根冠、③分生区、②伸长区、①成熟区.

④根冠位于根的顶端,属于保护组织,细胞比较大,排列不够整齐,像一顶帽子似地套在外面,具有保护作用.

③分生区被根冠包围着,属于分生组织,细胞很小,细胞壁薄,细胞核大,细胞质浓,具有很强的分裂能力,能够不断分裂产生新细胞,向下补充根冠,向上转化为伸长区.

②伸长区在分生区上部,细胞逐渐停止分裂,开始迅速伸长,是根伸长最快的地方,是根深入土层的主要推动力,能够吸收水分和无机盐.

①成熟区也叫根毛区;在伸长区的上部,细胞停止伸长,并且开始分化,表皮一部分向外突起形成根毛.根吸收水分和无机盐的主要部位.成熟区及其上部,根内部一部分细胞分化形成导管,能输导水分和无机盐.植物细胞都有细胞壁.因此叙述正确的是①成熟区是吸收水分和无机盐的主要部位.

故选A.

填空题
阅读理解
Fifty–eight percent of the teachers interviewed in the Association of Teachers and Lecturers (ATL) questionnaire had come across copying among their pupils. Gill Bullen from Itchen College in Southampton, for example, said, "Pieces handed in by two students were identical and significantly better than either of them could have done. Not only that, the essays handed in didn't quite answer the title question I had set". A teacher from Leeds said, "I had one piece of work so bravely cut and pasted that it still contained ads from the web page."  
Connie Robinson from Stockton Riverside College said, "With less able students it is easy to spot copying as the writing style changes in the middle of the assignment, but with more able students it is sometimes necessary for tutors to carry out Internet research to identify the source of the copy."
Mary Bousted, general secretary of the ATL, said," Teachers are struggling under a mountain of cut-and-pasting to spot whether work was the student's own or copy." She called for policies to stop copying, and asked for help from exam boards and the government in providing resources and techniques to detect cheats.
But there was another side. "I have found once students clearly understand what copying is, its consequences and how to reference correctly so they can draw on published works, copying becomes less of a problem," said Diana Baker from Emmanuel College, Durham.
"I think the majority of students who engage in copying do it more out of ignorance than the desire to cheat. They really want to succeed on their own."
53. The passage mainly wants to tell us ____________.
A. the benefits of the Internet for students
B. web copying is a serious problem in the UK
C. the ways to find web copying for teachers
D. how we can use the Internet to do homework
54. The underlined word “identical” (Paragraph 1) probably means ____________.
A. excellent
B. contrasting
C. the same
D. complex
55. What is TRUE according to Connie Robinson?
A. It’s not easy to find the less able students copy from the Internet
B. It’s difficult to find whether the more able students have copied.
C. The less able student will not change their writing style when copying.
D. The more able students needn’t copy from the Internet.
56. What’s the writer’s attitude towards “copying”?
A. The writer doesn’t tell us.
B. The writer feels angry about it.
C. The writer thinks it doesn’t matter.
D. The writer approves of it.