问题 实验题

经调查得知某草原生态系统的营养结构共有四个环节(用A.B.C.d表示)。研究发现,一年中流经这四个环节的能量列表如下:

(1)根据上表的数据可以推算出该草原生态系统的食物链是                        

(2)草原生态系统中除了上表中A.B.C.d四种生物外,还包括                                    成分;

(3)如果该草原生态系统受到农药的污染,则在       中含有的农药富集量最多;

(4)在这个生态系统中b的数量大量减少,则a的数量的变化是                

(5)该草原生态系统的营养结构简单,自动调节能力       

答案

(1)d→a→b→c;(2)分解者;非生物;(3)c;(4)先增多后减少;(5)小;

题目分析:(1)生态系统中物质和能量的流动沿着食物链和食物网的方向会逐渐减少的,根据能量从多到少依次是D.A.B.c,因此食物链是d→a→b→c;

(2)食物链中只有生产者和消费者,要将生态系统补充完整,还缺少分解者和非生物成分;

(3)生物富集作用是指环境中一些有毒物质,通过食物链在生物体内不断积累的过程,因为这些有毒物质化学性质稳定,在生物体内是难以分解、无法排出的,所以随着营养级的升高而不断积累,危害最大的是这一食物链的最高级消费者,该生态系统中c的营养级最高,c的体内农药积累的最多;

(4)如果b的数量大量减少,那么a因为天敌减少,数量会增加,那么d的数量会减少,接着a会因为食物减少数量又会下降;

(5)一般来说,生态系统中的生物种类越多,营养结构越复杂,自动调节能力就越大,反之,调节能力就小。

解答题
阅读理解

阅读理解

     One stormy night many years ago,an elderly man and his wife entered the hall of a small hotel in

 Philadelphia.Trying to get out of the rain,they came the front desk hoping to get some shelter for the night.

     "Could you possibly give us a room here?" the husband asked.

     The clerk,a friendly man with a winning smile,looked at the couple and explained that there were three

conventions in town."All of our rooms are taken," the clerk said."But I can't send a nice couple like you out into the rain at one o'clock in the morning.Would you perhaps be willing to sleep in my room?It's not

exactly a suite,but it will be good enough to make you folks comfortable for the night."

     When the couple declined,the young man pressed on."Don't worry about me;I'll make out just fine.

" the clerk told them.So the couple agreed.

     As he paid his bill the next morning,the elderly man said to the clerk,"You are the kind of manager who should be the boss of the best hotel in the United States.Maybe someday I'll build one for you." The

looked at them and smiled.The three of them had a good laugh.As they drove away,the elderly couple

agreed that the helpful clerk was indeed exceptional,as finding people who are both friendly and helpful

isn't easy.

     Two years passed.The clerk had almost forgotten the incident when he received a letter from the old

man.It recalled that stormy night and enclosed a roundtrip ticket to New York,asking the young man to

pay them a visit.

     The old man met him in New York,and led him to the corner of Fifth Avenue and 34th street.He then

pointed to a great new building there,a pale reddish stone,with turrets and watchtowers thrusting up to the sky."That," said the older man,"is the hotel I have just built for you to manage." "You must be joking," the

young man said."I can assure you I am not,"said the older man,a sly smile playing around his mouth.

     The older man's name was William Waldorf Astor,and that magnificent structure was the original

WaldorfAstoria Hotel.The young clerk who became its first manager was George C.Boldt.This young

clerk never foresaw the turn of events that would lead him to become the manager of one of the world's

most glamorous hotels.

1. The purpose of the following author writing this story is to________.

A. give people a good laugh

B. cover some facts

C. promote the business of WaldorfAstoria Hotel

D. deliver a lesson

2. Which of the following statements about the story is NOT true ?

A. The story took place at about one a.m..

B. The old couple was too poor to afford a luxurious room.

C. The clerk was willing to help those in need.

D. The clerk received an unexpected invitation from the old man.

3. The underlined word "conventions" in Para 3.can be replaced by________.

A. rooms    

B. suites

C. meetings    

D. hotels

4. Which of the following proverbs suits the story the best?

A. Every little thing helps.

B. Make hay while the sun shines.

C. Man proposes;God disposes (处理,决定).

D. One good turn deserves another.