问题 解答题

动物在自然界中有哪些作用,请分别从生态平衡、物质循环和与其他生物的关系等方面说明,并各举一例.

答案

动物在自然界中的作用:(1)在生态平衡中的作用,食物链和食物网中的各种生物之间存在着相互依赖、相互制约的关系.生态平衡是指生态系统中各种生物的数量和比例总是维持在相对稳定的状态.如果食物链或食物网中某一环节出了问题,就会影响到整个生态系统,而动物作为生态系统的消费者在维持生态平衡中起着重要作用.另外动物和植物是相互依存的,缺一不可,就像一个链条上的一环,少了它就不成为链了,而且各种物质流,信息流及能量流都将中断,最终就会导致生态系统的崩溃.如青蛙减少,蝗虫泛滥,蛇减少老鼠增多;

(2)动物能促进生态系统的物质循环,动物作为消费者,直接或间接地以植物为食,通过消化、吸收,将摄取的有机物变成自身的能够利用的物质.这些有机物在体内经过分解释放能量,产生二氧化碳、尿液等,二氧化碳、尿液可以被生产者利用.动物排出的粪便或遗体,然后在微生物的作用下,变为无机物回到生态系统中,可见动物能促进生态系统的物质循环.如动物的呼吸作用分解有机物,加快二氧化碳的循环;

(3)帮助植物传粉、传播种子,如蜜蜂采蜜;某些动物数量过多时也会危害植物,如蚜虫吮吸汁液、蝗灾等.

故答案为:

(1)在生态平衡中的作用,食物链和食物网中的各种生物之间存在着相互依赖、相互制约的关系.生态平衡是指生态系统中各种生物的数量和比例总是维持在相对稳定的状态.如果食物链或食物网中某一环节出了问题,就会影响到整个生态系统,而动物作为生态系统的消费者在维持生态平衡中起着重要作用.另外动物和植物是相互依存的,缺一不可,就像一个链条上的一环,少了它就不成为链了,而且各种物质流,信息流及能量流都将中断,最终就会导致生态系统的崩溃.如青蛙减少,蝗虫泛滥,蛇减少老鼠增多;

(2)动物能促进生态系统的物质循环,动物作为消费者,直接或间接地以植物为食,通过消化、吸收,将摄取的有机物变成自身的能够利用的物质.这些有机物在体内经过分解释放能量,产生二氧化碳、尿液等,二氧化碳、尿液可以被生产者利用.动物排出的粪便或遗体,然后在微生物的作用下,变为无机物回到生态系统中,可见动物能促进生态系统的物质循环.如动物的呼吸作用分解有机物,加快二氧化碳的循环;

(3)帮助植物传粉、传播种子,如蜜蜂采蜜;某些动物数量过多时也会危害植物,如蚜虫吮吸汁液、蝗灾等.

选择题
阅读理解

阅读理解。

     "Tomorrow is another day"- this line has impressed various people at various times. It's now 70 years

after it appeared in the film, but it still seems to hold its power especially during an economic downturn.

The phrase comes from a film adaptation of Margaret Mitchell's successful 1936 novel Gone With the

Wind. It's set in the American South and tells the story of a strong heroine, Scarlett O' Hara, who struggles to find love during the Civil War and, afterwards, of her strength in surviving the war and its hardships.

     Love story  

     In a moment of despair, Scarlett finally realizes that her love belongs to Rhett Butler. For many

audiences, it is the theme of love and struggle that has kept the movie alive. While the burning of Atlanta

might seem irrelevant to today's viewers, the timeless theme of love keeps its ability to touch people.

     With a promise to her lover still in her mind, Scarlett chooses to stay in the midst of war and take care of Melanie. But her heart is broken when Rhett just walks away, leaving the woman that he once loved

with cruel words, "Frankly, dear, I don' t give a damn."

     Great epic

     The film shows the love-hate relationship of these characters, but also American history, the fall of the Confederacy and the following period of Reconstruction in the South. The background made this film a

true classic in the epic genre.

     When the film opened after World War II, French viewers loved it, and it reminded them of their fight

against the Nazis. In 1940 Shanghai, during the War of Resistance Against Japanese Aggression, people

stood in line for hours to watch this film, and saw the same suffering they were having as well as the hope

and possibility of building a new homeland from the ruins.

     Each nationality could identify with the story and see it as a victory. In fact, Gone With the Wind

never lost its charm and ability to inspire and amaze.

     Biggest of all time

     The film had five directors, 15-plus screenwriters, and an unexpected $3.9 million budget. The film

brought in $ 200 million, which makes it the biggest selling film of all times in North America. It also won

10 Academy awards in 1940.

1. The underlined "it" in the first paragraph refers to _______.

A. the novel Gone with the Wind            

B. "tomorrow is another day" 

C. the movie Gone with the Wind            

D. the Academy Award

2. The text is written mainly to _______. 

A. celebrate the anniversary of Margaret Mitchell

B. introduce how the film was directed and filmed

C. throw light on the charm of the movie "Gone with the Wind"

D. inspire people to struggle the economic downturn

3. It can be concluded that Scarlett O' Hara is _______.

A. optimistic and lucky            

B. childish and realistic

C. caring and stubborn              

D. strong-minded and persistent  

4. The passage mentions Shanghai in order to _______.

A. prove that the background of the movie touched viewers 

B. describe how popular the movie was at that time

C. point out that Shanghai was a center of entertainment

D. tell us that Chinese were suffering the War then.