问题 解答题

海洋深处没有绿色植物生存是因为水的压力太大.______.

答案

光在海水中的穿透性有浅到深越来越弱,最浅处光最强,有红光也有蓝紫光,有利于绿藻利用,所以是绿藻;往下一些红光穿透性不强被海水吸收,能利用起来用作光合作用的只剩蓝紫光,褐藻有利于吸收蓝紫光,是褐藻;再往下,蓝紫光也被吸收一部分,是红藻;最深处没有光,因此没有植物生存,只有一些硫化菌,因此题干说法错误.

故答案为:×.

单项选择题

阅读以下文字,完成以下问题。
由于生理遗传机能、食物内容、生活环境的不同,野生动物群体里有许多本来仅属于它们的致命疾病,而人类对这类疾病中的一部分,可能缺乏免疫力,一经感染,就容易爆发大规模疫情。“非典”、艾滋病、结核病、出血热以及许多寄生虫病,都与野生动物有关。
野生动物身体里的病毒怎么会跑到人类身上除了老饕们把病毒吃进自己肚子里,厨师们在屠戮野生动物时把病毒揉进自己眼睛里或吸人自己鼻腔里这些直接解释之外,也包括生态学方面的解释。
人类对自然界的大规模破坏(特别是砍伐森林),使得野生动物们食物匮乏,它们不得不从森林深处迁移到森林边缘的农田、果园、牧场就食,这样就可能把身上的病毒传染给家养的牲畜,而人吃了这些被传染的牲畜之后,也就[ ]了,这叫间接感染。
此外,由于森林锐减,食物链被严重破坏,野生动物的食物结构也就被迫改变,变得什么都吃,也可能把自己弄得浑身是毒,体内毒性更大,继而把这些病毒传染给家畜和人类。因此,人类的某些疫病是人类破坏自然生态环境的结果。
野生动物的锐减还将造成严重的生态失衡。生态失衡给人类带来的破坏,则不仅仅是疾病,也包括经济灾难乃至人类的生存危机。
大自然的生态平衡是通过从植物到大型食肉动物之间的食物链来实现的。某一类野生动物种群的减少或灭绝,都可能造成生态失衡。远的不说,农牧业方面虫害、鼠害的加剧,都与这些虫、鼠的天敌(如蛇类、鸟类)数量锐减有关。虫、鼠害加剧的结果,一是直接的农牧业损失,一是导致生化灭虫剂、灭鼠剂的广泛使用,这些生化物质即使经过淘洗,其残留部分最终还是进入人体。
这里还要特别提到虎、豹、狮等,它们是广阔的野外生态系统的总控制师。若它们灭绝了,食草动物的种群数量就会无限制地扩大,草原被吃成沙漠荒土,食草动物们最终也将灭绝。所以,任何一个生物种群,都是大自然的精妙安排,绝非可有可无。老虎维持着大自然的水草丰美,这是一种精妙安排;而在手握利器的人类对虎皮、虎骨酒等孜孜以求之下,这种安排又是多么脆弱!
野生食草动物的天敌的消失和家养牲畜的数量增长,导致了我国西北土地的沙漠化,沙漠化引起沙尘暴,沙尘暴早就让人们戴上了口罩,高达数百米的沙尘暴曾经把兰州市“掩埋”了五天。沙尘暴同样也会引发传染病和心理恐慌,它对人类健康的戕害,虽然不像“非典”疫情一日一报那样清晰,但它损害人类健康而造成的死亡人数,绝对要超过“非典”。

以下叙述,符合原文内容的一项是( )。

A.动物之间的生物链保持了生态平衡,但大量生化农药的使用,直接而彻底地破坏了整个生态系统的平衡

B.沙尘暴使人们戴上了口罩,以致引发疾病和心理恐慌,它与“非典”危害一样严重

C.人与野生动物的遗传机能、食物内容、生活环境的不同,人与野生动物的免疫能力大相径庭,因而人类容易发生大规模疫情

D.人类的某些疾病,如SARS,是人类自身破坏生态引发的

阅读理解

阅读理解。

     Sorry to say, our brains naturally start slowing down at the Cruelty young age of 30. It used

to be thought that this couldn't be helped, but new studies show that people of any age can train

their brains to work faster. "Your brain is a learning machine," says University of California scientist

Dr. Michael Merzenich. Given the right tools, we can train our brains to act like they did when we

were younger. All that's required is the practice designed just for the purpose: a few exercises for

the mind.

    Merzenich has developed a computer-based training method to speed up the process(过程)in

which the brain deals with information  ( positscience. com). Since much of the data we receive

comes through speech, the Brain Fitness Program works with language and hearing to better

speed and accuracy (准确性).

     Over the course of training, the program starts asking you to distinguish (辨别) sounds (between

"dog" and "bog", for example) at an increasingly faster speed. It's a bit like tennis instructor, says

Merzenich, hitting balls at you-faster and faster to keep you challenged(受到挑战).

You may start out slow, but before long you're pretty quick,

    The biggest finding in brain research in the last ten years is that the brain at any age is highly plastic.

If you ask your brain to learn, it will learn. And it may even speed up while in the process.

     To keep your brain young and plastic you can do one of a million new activities that challenge and

excite you: playing table tennis or bridge, doing crossword puzzles, learning a language. . . "When

it comes to preventing ageing, you really do ' use it or lose it' ,"says Barbara Sahakian, professor at

Cambridge University.

1. Dr. Merzenich's training method mainly depends on_________.    

A. speech training

B. computer languages

C. the activities one joins in

D. the information being dealt with

2. By saying"the brain at any age is highly plastic", the writer probably means the brain can be_____.  

A. used                          

B. mastered

C. developed                      

D. researched

3. What can we learn from the text?  

A. Practice makes a quick mind.

B. Brain research started ten years ago.

C. Dr. Merzenich is a scientist in computer.

D. People believed nothing could stop the brain slowing down.

4. Which of the following agrees with the writer's idea?

A. The training methods work better for the old.

B. People should use the brain to stop it from ageing.

C. The training of the brain should start at an early age.

D. It's necessary to take part in as many activities as possible.