问题 问答题 简答题

某一池塘中有三个优势种群,分别是鳙鱼、浮游动物A和浮游植物B,其中鳙鱼以浮游动物A为食,浮游动物A以浮游植物B为食。回答下列问题:

(1)为提高池塘鳙鱼的产量,采取向池塘中施肥和捕捞小型野杂鱼等措施,其中施肥的作用是直接提高__________的种群数量。捕捞野杂鱼的作用是降低其与鳙鱼对__________、__________和空间等资源的竞争。

(2)若大量捕捞使池塘中的鳙鱼数量减少,则短时间内会导致__________的种群数量迅速下降。

(3)若池塘施肥过量,一段时间后,池塘内上述三个优势种群消失了两个,它们是__________,消失的主要原因是缺少__________。再经过一段时间后,仅存的一个优势种群也基本消失,而另一类生物如微生物大量繁殖,使水体变黑发臭,该类生物在生态系统中属于__________。

答案

参考答案:

(1)浮游植物B;食物;氧气(或溶解氧)

(2)浮游植物B

(3)浮游动物A和鳙鱼;氧气(或溶解氧);分解者

解析:(1)施肥的作用有利于浮游植物B的生长,提高了其种群数量。鳙鱼和其他杂鱼在食物、氧气、空间资源等存在竞争,所以捕捞野杂鱼,减弱竞争。 (2)、(3)大量捕捞使池塘中的鳙鱼数量减少,浮游动物A由于缺少天敌数量增加,以大量浮游植物 B为食,使其数量减少。大量施肥,导致水体富营养化,藻类大量繁殖,水中氧气被大量消耗,导致浮游动物A和鳙鱼缺少氧气而死亡。浮游动物A和鳙鱼大量死亡,尸体腐烂导致分解者--微生物大量繁殖。

问答题
阅读理解

阅读理解。

     Andy: I think being honest is the most important. Honesty is the best policy(原则). It is where a good

friendship(友谊) starts. Friends must be able to trust one another. If you don't tell the truth(事实), you

may lose your friends' trust. Good friends always trust in one another and do things honestly.

     Jim: Being generous(慷慨的) is important. It means sharing things with each other and sharing makes

a friendship grow. Being generous doesn't mean you have to give your lunch money or your clothes to

others. It means we share our ideas and feelings. By sharing them, we help our friends know us better.

      Mary: I think it's necessary for us to understand a friend. Everyone needs understanding. When

friends have a problem, talking about the problem can make it easier to solve. I must try to put myself

in my friend's place, so I can understand the problem and my friend better.

1. What does Andy think is the most important to make friends?

A. Being honest

B. Being generous.

C. Understanding a friend

D. Keeping a secret.

2. Jim thinks friends should share_______.

A. their ideas

B. their feelings

C. their money

D. their ideas and feelings

3. Mary tries to put herself in her_______ place to understand her friend better.

A. own

B. friend's

C. classmate's

D. teacher's

4. Friends must be able to trust one another. "trust" means_______.

A. 表扬

B. 批评

C. 反对

D. 信任

5. When friends have a problem, _______ can make it easier to solve.

A. fighting(打架)against each other

B. throwing it away.

C. talking about the problem

D. asking the friends to forgive.(宽恕)