问题 实验题

下图是某生态系统的食物网,请根据图回答:

(1)该食物网中共有      食物链。其中最长的一条是                   

(2)该生态系统中,草属于        ,兔、狐等属于           ,还有肉眼看不到的细菌、真菌等属于               ,除此之外生态系统的组成还包括图中没有表示出来的                

(3)该食物网中,数量最多的生物是           ,数量最少的是           

(4)如果将狐、鹰等肉食动物大量捕杀,兔的数量将会出现什么样的变化?                              

答案

(1)5,草→鼠→蛇→鹰;

(2)生产者 消费者 分解者 非生物部分

(3)草,鹰

(4)先增加后减少

题目分析:(1)食物链反映的是生产者与消费者之间的吃与被吃这种关系,所以食物链中不能出现分解者.食物链的正确写法是:生产者→初级消费者→次级消费者…注意起始点是生产者,图中草是生产者,图中的食物链有:①草→兔→鹰②草→兔→狐③草→鼠→狐④草→鼠→鹰⑤草→鼠→蛇→鹰共5条.

(2)生态系统包括生产者、消费者、分解者和非生物部分,生产者主要指绿色植物,能够通过光合作用制造有机物,为自身和生物圈中的其他生物提供物质和能量;消费者主要指各种动物,在促进生物圈中的物质循环起重要作用;分解者是指细菌和真菌等营腐生生活的微生物,它们能将动植物残体中的有机物分解成无机物归还无机环境,促进了物质的循环.图中草属于生产者,所有的动物属于消费者.所以缺的是非生物部分.

(3)草属于生产者,因为在生态系统中营养级别最低数量最多,所以数量最多的生物是草,鹰的营养级别最高其数量最少.

(4)生态系统具有一定的自动调节能力,食物链中的生物是相互制约、相互依赖的,一种生物数量的变化会导致其他生物数量随之发生相应的变化.若人们大量捕捉狐和鹰,因为兔和鼠由于天敌减少而大量繁殖,所以兔和鼠的量会增加,以后,由于兔和鼠的过度繁殖,食物减少,数量也随之减少,最后由于生态系统具有自我调节能力,处于生态平衡状态. 

阅读理解

阅读理解。

     Everyone has worries. How do you deal with your worries? There is always something you can do

to help yourself feel less worried. Sitting there worrying is no fun and it won't solve your problems.

Grades at school are often a top worry for kids. if you worry most about grades, ask yourself these

questions:

    ●Why are grades important? What do grades mean to me?

    ●How do I get ready for class? Do I go over my notes even when there isn't a test?

    ●Do I have a good place to do my homework?

    ●Have I tried different ways of studying?

    If your worry is about a fight you had with your friend, you might write down al! the things you could

do-write a note to him or her, invite him or her to watch a basketball game, say sorry to him or her and

so on. Once you have a list of things you could do, you can choose one thing that could get your friend

back.

     You can ask for help when you're worried. You can find someone to talk to, such as your parents,

friends, and teachers.

1. What do kids often worry most about?

A. Their hobbies.

B. Their homework.

C. Their marks at school.

D. A fight with their friends.

2. According to the passage, when you're worried, you'd better ______.

A. work hard

B. talk to someone

C. get ready for class

D. write down your worries

3. If you're worried about grades, DON'T ask yourself "______".

A. Why are grades important?

B. What do grades mean to me?

C. How do I get ready for class?

D. Why not give up my studies?

4. If you had a fight with a friend, you could _______.

A. invite him or her to watch a game

B. put the blame on him or her

C. try to make new friends

D. leave him or her alone

5. What does the passage mainly tell us?

A. Who is often worried.

B. When people are worried.

C. How to deal with worries.

D. What kinds of worries people have.

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