问题 问答题 论述题

论述生态系统的控制论特点。

答案

参考答案:

生态系统不同于一般系统的调控。

(1)无目标、非中心的自我控制。自然界在亿万年进化历程中形成了十分精巧的自我调节和控制能力。它无独立的调控部件,是非中心的自我控制。主要通过各生物种相互联系使整个群落自发地向顶极方向发展。(2)多层次控制。自然生态系统总是由有垂直分离特性的层次构成,大系统套小系统,小系统套更小的系统。在同一层次内,系统又由相互联系,但又彼此相对独立的组份构成,形成系统的水平分离特征。

(3)多元重复。多元重复是指在生态系统中,有一个以上的组分具有完全相同或相近的功能,或者说在网络中处在相同或相近生态位上的多个组成成分,在外来干扰使其中1个或2个组分被破坏的情况下,另外1个或2个组分可以在功能上给予补偿,从而相对地保持系统输出稳定不变。

例如:植物的种子和动物的排卵数大大超过环境中可能容纳的下一代数目;同一食草动物常消费众多的植物种类;同一种生物残体为数以百计和各种大小生物所分解利用等等。这就使得生态系统在遇到干扰之后,仍能维持正常的能量和物质转换功能。

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     When we talk about stars, especially women stars, it seems that they are always young, pretty and own charming body shapes. But recently a Britain's Got Talent(英国达人)star Susan Boyle has changed our    views absolutely.

     Simon Cowell, one of the judges of the talent show spoke of his shock over Ms Boyle's voice. "This     lady camp up, and I'm thinking, 'This will take five seconds and I can go to have a cup of tea'. That           changed when she began to sing I Dreamed to Dream from Les Miserables. She knew we were going to  have that reaction and just to see that look of satisfaction on her face through -it was one of my favorite    moments," Cowell said.

     The performance was posted on line and before long, the 47-year-old Scottish woman has been           famous all over the world.

     Speaking from her home in Scotland, Ms Boyle said that she hasn't thought of changing her                  appearance. She said that her friend helped her with make-up. "I mean, that's hardly a makeover," she      added. Ms Boyle also spoke of the reason she first began to explore her vocal talents, "I was kind of slow at school, so getting like singing was a good way of hiding behind that and thus it built my confidence. "

1. Susan Boyle is _________

A. a judge  

B. a reporter  

C. a beautiful  

D. a Scottish woman

2. Susan Boyle had a look of satisfaction on her face when she was singing because______.

A. she was confident of her singing

B. she was satisfied with the judges

C. she was pretty and in good shape

D. she sang the song I Dreamed a Dream from Les Miserables

3. According to the passage, which is NOT true?

A. It was the vocal talents that built Susan's confidence

B. Susan Boyle was not good at her lesson when at school.

C. Susan Boyle became famous because of her appearance.

D. Simon Cowell didn't think Susan Boyle a good singer at the first sight.

4. What can we learn from Susan Boyle's success

A. It's never too old to learn.

B. It's easier to succeed at the age of 47.

C. If you have a dream, try to make it come true!

D. If you are not able to study well, to be a singer instead.