问题 实验题

下图为某生态系统中的食物网,据图回答有关问题:

(1)该食物网中,一共有        条食物链。

(2)图中最长的食物链中,属于第三营养级的生物是        

(3)正常情况下,该食物网中积累有害物质最多的生物是        

(4)若要构成一个完整的生态系统,图中还缺少的成分是                     

答案

(1) 5        (2)蛇      (3)鹰

(4)分解者和非生物成分(二者写全才给分)

题目分析:(1)该生态系统有5条食物链,分别是:草→鼠→蛇→鹰,草→鼠→鹰,草→兔→鹰,草→鼠→狐,草→兔→狐。

(2)在最长的食物链:“草→鼠→蛇→鹰”中,草是生产者,其余都是消费者,其中鼠吃草,鼠是初级消费者,蛇吃鼠,蛇是次级消费者,鹰位于食物链的末端,是最高级消费者,食物链上的每一个环节叫做一个营养级,在“草→鼠→蛇→鹰”这个食物链中,草属于第一营养级,鼠属于第二营养级,蛇属于第三营养级,鹰属于第四营养级,也是三级消费者。

(3)生态系统中的能量沿着食物链单向传递,且逐级递减,因此,生产者草的数量最多,鹰位于食物链的末端,是最高级消费者,如果有毒物质流入生态系统,由于存在生物富集现象,鹰体内有毒物质的含量最高。

(4)生态系统由生物成分和非生物成分两部分组成,生物成分包括:生产者、消费者和分解者,图中食物网中具有了生产者和消费者,若要构成一个生态系统还缺少分解者和非生物成分。

点评:此题为基础题,解答此题的关键是掌握生态系统的组成和食物链的内容以及会分析生物的数量变化。

阅读理解

A big company wanted a clerk,so John went there. In the interview,the director asked him a question. “Who paid for your school?” “My mother paid for it by washing clothes.”

Hearing this,the director asked John to show his hands. John showed a pair of hands that were perfect . The director said,“When you go back today,go and clean your mother’s hands,and then see me tomorrow morning.”   

When John went back,he happily asked his mother to let him clean her hands.

However,his tears fell as he cleaned his mother’s hands. It was the first time he noticed that there were too many bruises(伤痕)in his mother’s hands. After finishing the cleaning of his mother’s hands,John quietly washed all the remaining clothes for his mother.

Next morning,John went to the director’s office. The director noticed the tears in John’s eyes and asked,“ Please tell me your feeling.”John said,“Number 1,I know now what appreciation(感恩) is. I would not be successful if my mother didn’t do these things. Number 2,by helping my mother,now I realize how difficult it is to get something done.”The director said,“This is what I want to be my clerk. You can get the job.”

小题1:John went to the big company to         .

A.look for his mother

B.ask for a job

C.ask the director for help

D.look for the director小题2:John’s mother was a(n)         .   

A.office clerk

B.director

C.farmer

D.clothes cleaner小题3:From the underlined sentence,we learn        .

A.John tried his best to wash clothes for his mother

B.John often helped his mother do the housework

C.John hardly helped his mother wash clothes

D.John often helped his mother wash hands小题4:John felt         when he cleaned his mother’s hands.

A.happy

B.sad

C.angry

D.tired小题5:Why did the director hire(雇佣)John?

A.Because he thought John 1earned appreciation.

B.Because he thought John had a good education.

C.Because he thought John worked very hard.

D.Because he thought John could help his mother.

填空题