问题 解答题

某学校一个生物科技兴趣小组的几位同学,通过对一个稻田生态系统的观察,发现稻田里主要的生物有:水稻、昆虫、青蛙、捕虫的小鸟等.他们绘制出了该稻田生态系统示意图.请结合所学知识回答:

(1)图中所含食物链有______条.

(2)此生态系统的______沿食物链和食物网流动.

(3)生态系统中的生产者进行光合作用,其产物是______.

(4)在水稻播种前应当测定种子的发芽率.重复测3次,取3次的______作为测定结果.

(5)在昼夜温差较大的地区,通常水稻的产量较高,请你分析原因:______.

答案

(1)食物链反映的是生产者与消费者之间吃与被吃这种关系的,所以食物链中不应该出现分解者和非生物部分.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,箭头指向消费者.图中的食物链有:水稻→昆虫→鸟;水稻→昆虫→青蛙.因此共有2条食物链.

(2)在生态系统中,如水稻→昆虫→青蛙,昆虫吃水稻,水稻进行光合作用储存的物质和能量就进入了昆虫的体内,青蛙吃昆虫,昆虫体内储存的物质和能量就到了青蛙的体内.因此物质能量就是沿着食物链和食物网流动的.

(3)绿色植物通过叶绿体,利用光能,把二氧化碳和水转化成储存能量的有机物,并且释放出氧气的过程,叫做光合作用.生产者是指能进行光合作用,为植物自身、消费者、分解者提供有机物(食物)和氧气的绿色植物.因此生态系统中的生产者进行光合作用,其产物有机物和氧气.
(4)种子的发芽率是指发芽的种子数占供检测的种子数的百分比.由于抽测带一定的偶然性,为了避免测试的误差,提高可信度.一般取测试次数的平均值作为测试结果.因重复测3次,故应该取3次的实验的平均值作为测定结果.

(5)在昼夜温差较大的地区,白天气温高光合作用旺盛制造的有机物多,到了夜间气温降得比较低的可有效地抵制水稻的呼吸作用,减少因为呼吸作用对有机物的消耗,使有机物得到更多地积累,从而提高水稻的产量.

故答案为:

(1)2;

(2)物质和能量;

(3)有机物和氧气;

(4)平均值;

(5)白天温度高,光合作用制造的有机物多;晚上温度低,呼吸作用消耗的有机物少.

阅读理解

Quit while you're ahead

I am one of those people who are terrible at saying no.I take on too many projects at once, and spend too much of my time doing things I'd rather not be doing.I get work done, but it's not always the best I can do, or the best way I could spend my time.

That's why my newest goal, both as a professional and a person, is to be a quitter.

Being a quitter isn't being someone who gives up, who doesn't see important things through to the end.I aspire (渴望) to be the opposite of that.The quitter I want to be is someone who gets out when there's no value in what he's doing, or when that value comes at the expense of something more important.

A friend of mine once told me, "I knew I was an adult when I could stop reading a book, even after getting 500 pages into it." Strange though it sounds, we all tend to do this.We get involved in something, realize we don't want to be a part of it, but keep on going.We say "Well, I've already invested so much time in this, I might as well stick it out."

I propose the opposite: quit as often as possible, regardless of project status or time invested.If you're reading a book, and don't like it, stop reading.Cut your losses, realize that the smartest thing to do is to stop before your losses grow even more, and quit.Instead of reading an entire book you hate, read half of a bad one and half of a good one.Isn't that a better use of your time?

Step back for a second.Let's learn how to say "no" at the beginning, or in the middle, and free up more of our time to do the things we'd like to be doing, and the things actually worth doing. Saying no is hard, and admitting a mistaken yes is even harder.If we do both, we'll start to make sure that we're spending our time creating value, rather than increasing our losses.Let's be quitters together.

小题1:The author wants to be a quitter, because he _____.

A.hopes to improve his personality

B.wishes to have more time for relaxation

C.expects to make more efficient use of his time

D.has found it hard to do several things at one time小题2:In what circumstances does the author suggest quitting is a good idea?

A.When you feel tired and need a rest.

B.When you know a task cannot be finished.

C.When you meet with difficulties along the way in your life.

D.When you realize what you are doing is not worth the time.小题3:If you stop reading a book you hate, the author might think that ______.

A.you are wise to cut your losses

B.it's a pity that you have wasted so much time

C.you should finish a book that you have started

D.you should regret choosing the wrong book小题4:The message the author tries to convey is to ______.

A.learn to say no

B.live your life to the fullest

C.create more value

D.stop doing many things at once

单项选择题