问题 选择题

利用兰花的一段茎尖,能在一年内生产出上百万株兰花幼苗的方法是(  )

A.植物组织培养

B.嫁接

C.出芽生殖

D.分裂生殖

答案

A、植物的组织培养是指在无菌的条件下,将植物的茎尖、茎段或叶片等切成小块,培养在特制的培养基上,通过细胞的增值和分化,使它逐渐发育成完整的植物体.利用这种技术,可以在短时间内大批量的培育成所需要的植物新个体;还可以防止植物病毒的危害,极大的提高了农业生产效率.故符合题意.

B、嫁接是指直接把一种植物的枝条或芽,接在另一种植物体上,是接在一起的两部分长成完整的植物体.利用嫁接可以繁育优良的品种,但不能快速繁殖.故不符合题意.

C、出芽生殖是指由细胞分裂产生子代,在一定部位长出与母体相似的芽体,即芽基,芽基并不立即脱离母体,而与母体相连,继续接受母体提供养分,直到个体可独立生活才脱离母体.是一种特殊的无性生殖方式,不能在短时间内快速繁殖出大量的新个体.故不符合题意.

D、细胞的分裂生殖是指由一个细胞分成两个细胞的过程,不能在短时间内快速繁殖出大量的新个体.故不符合题意.

故选:A

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阅读理解

阅读下面文章,根据要求回答下列问题。

                                                 British English and American English

     Many students want to know the differences between American English and British English. Written English

is more or less the same in both Britain and America, though there are some spelling differences. For example,

the words colour, centre and travelled are spelt color, center, and traveled in American English.

     The differences in the spoken language are greater. For example, Americans say dance /dns/, and in southern

England they say /da:ns/. In America, they pronounce not./nt/, in southern England they say /not/. However,

most of the time, people from the two countries do not have any difficulty in understanding each other.

     How did these differences come from? There is no quick answer to this question. When people from England

travelled to other countries they took the English language with them. At first, the language stayed the same as

the language used in Britain, but slowly the language began to change from one part of the world.

     Sometimes, the English spoken in America or Canada or Australia changed, but sometimes the language

spoken in these places stayed the same while the language in England changed. For example, 300 years ago, the

English talked about "autumn". But Americans still talk about "fall" just as people do in some parts of western

England. In the same way Americans use the expression "I guess" (meaning "I think") just as the British did 300

years ago.

     A great many words and expressions have come into the language from American English, for example

movie, gas, store, mail, right away (at once), way of life and so on.

     American English has changed over the centuries, too. There are several reasons for this. One of the reasons

is that people travelled to America from all the European countries and from other parts of the world, too. They

started to use English, but they also brought in some words from old French. One of the States in the USA is

called "Florida". In Spanish this is "the land of flowers". There are a great many American Indian words, for

example, "to howl" means "to cry". And "cookbook" is a German word.

根据文章内容判断下列句子的对(T)与错(F)。

( )1. There are some differences between British and American English. So people from the two countries

            can hardly understand each other when talking to each other.

( )2. As time goes by, the English language stays the same.

( )3. Americans usually use "fall" instead of "autumn" when they talk about the seasons.

( )4. "Florida" means"the land of flowers" in American English.

( )5. People who travel to the USA add more words to American English.

根据文章内容,回答下列问题。

6. Which of the following words belongs to British English: movie, gas, mail or petrol?

    _______________________________________________________________________________

7. Please give the American way of spelling of the following words: colourful, metre and traveller. 

     _______________________________________________________________________________