问题 选择题

下列哪项不是肾单位具有的功能(  )

A.过滤血液

B.选择性重吸收

C.分泌氨

D.形成尿素

答案

尿的形成要经过肾小球和肾小囊壁的滤过作用,肾小管的重吸收作用以及肾小管壁的分泌作用.当血液流经肾小球时,除了血细胞和大分子的蛋白质外,其他的如水、无机盐、尿素、葡萄糖会滤过到肾小囊腔形成原尿;因此,肾单位具有过滤血液的作用.当原尿流经肾小管时,其中大部分水、部分无机盐和全部的葡萄糖被重新吸收回血液;表明肾单位具有选择性重吸收的功能.肾小管的远曲小管的功能是继续吸收水和钠离子.并向管腔内分泌氢离子和肌酐、马尿酸等,这对维持血液的酸碱平衡有重要作用.因此,肾单位具有分泌氨的功能.氨是人体内蛋白质的代谢废物,对人体有毒性,尿素就是对氨的一种解毒形式,有水溶性,可以经肾脏由尿排出.体内代谢产生的氨(主要来自胃肠道)被运送到肝脏,通过鸟氨酸循环转变为解毒的形式,就是尿素.所以合成尿素最主要的器官是肝脏.

故选:D

阅读理解

During the early years of American settlement, a new form of English was beginning to develop in the islands of the West Indies and the southern part of the mainland, spoken by the black population. The beginning of the seventeenth century saw the happening of the slave trade. Ships from Europe travelled to the West African coast, where they exchanged cheap goods for black slaves. The slaves were shipped in terrible conditions to the Caribbean islands and the American coast, where they were in turn exchanged for such products as sugar and molasses(糖蜜). The ships then returned to England, completing an “Atlantic triangle”of journeys, and the process began again. Britain and the United States had outlawed the slave trade by 1865, but by that time, nearly 200 years of trading had taken place. By the middle of the nineteenth century, there were over four million black slaves in America.

The policy of the slave-traders was to bring people of different language backgrounds together in the ships, to make it difficult for groups to plan rebellion. The result was the growth of several pidgin (混杂语言) forms of communication, and in particular a pidgin between the slaves and the sailors many of whom spoken English. Once arriving in the Caribbean, this pidgin English continued to act as a major means of communication between teh black population and the new landowners, and among the blacks themselves. Then, when children came to be born, the pidgin became their mother tongue, thus producing the first black Creole(克里奥尔语) speech in the region. This Creole English rapidly came to be used throughout the cotton plantations (种植园), and in the coastal towns and islands.

小题1:Which of the following shows the route of slave trade correctly?

A.EuropeWest African coastthe Caribbean islands and the American coastEurope

B.EuropeWest African coastEuropethe Caribbean islands and the American coast

C.West African coastEuropethe Caribbean islands and the American coastEurope

D.West African coastEuropethe Caribbean islands and the American coastWest African coast小题2:It can be inferred that the slaves in the same ship ____.

A.didn’t communicate with each other

B.could understand several languages

C.spoke different languages

D.came from the same place小题3:Creole speech comes from _____.

A.Spanish and English

B.English and an African language

C.a European language and an American language

D.an African language and an American language小题4:What is the text mainly about?

A.The history of slave trade.

B.“Atlantic triangle” of journeys.

C.Languages spoken in America

D.The birth of black English

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