2. 外语
  3. Now read the passage about energy flow in ecosystems. You will have 45 seconds to read the passage. Begin reading now.

Now read the passage about energy flow in ecosystems. You will have 45 seconds to read the passage. Begin reading now.

admin2012-01-14  41
问题
    Now read the passage about energy flow in ecosystems. You will have 45 seconds to read the passage.
    Begin reading now.
    Reading Time: 45 seconds
                    Energy Flow
    An important functional aspect of ecosystems is energy flow. In the 1920s, Charles Elton pointed out that there was a pyramid of trophic (food) levels: the base of the pyramid was composed of producers; above them were a smaller number of herbivores and above them a still smaller number of carnivores. Ecosystem ecologists usually express these relationships by the amount of energy passing through each of the trophic levels, i.e. the food chain, in a given period of time. There is always more energy passing through a lower level in a given unit of time than through a higher level.
Student A  Hey, Susan! How are you?
Student B  Hi, Frank! I’m fine. But, uh, I’m having some trouble with my experiment...
Student A  Oh? What’s wrong?
Student B  You know, I’ve been working on this experiment for more than half a year and I think the results will be quite promising and exciting. But now I have run into some problems with the lab apparatuses, and the experiment has begun to lag behind schedule. That’s really troublesome.
Student A  Oh, that sounds really bad! Are any of the apparatuses broken? Or maybe they just can’t meet the needs of your experiment?
Student B  Yeah. Actually, the apparatuses are quite old and haven’t been renovated for many years, so some new experiments really cannot be carried out with them.
Student A  But I don’t think you’ll just give up, will you?
Student B  Well, you’re right. I don’t want to give up. But now I really have no idea how to tackle this problem.
Student A  Maybe you can ask your supervisor for some help. If he’s convinced that your experiment is really valuable and promising, I think he’ll renovate the apparatuses in time.
Student B  I’ve thought about this. But the problem is that I’m not confident that I can convince him successfully, for the cost of renovation is actually not insignificant.
Student A  I see. Umm...here’s another thing maybe you can think about. Go to other labs which are better equipped to continue your experiment. I know there’re some good labs with very advanced apparatuses in the National Academy, and they can be opened to outsiders upon application.
Student B  Oh, really? That sounds like a better idea. Do you know how to apply for that?
Student A  I’m not quite clear about that, either. But I think you can check out the website. There must be some useful information there about that.
Student B  Very well! I’ll go and find it!
选项
答案The professor describes the process of energy flow in the food chain. According to the professor, the energy in organisms originates from the sun, and the amount of energy decreases as it moves up the food chain. Only a small amount of the solar energy is used by the lowest level of the food chain, namely plants. And from plants, herbivores, which feed on plants, lust get a little energy. Then carnivores, which feed on herbivores, still get a little of the energy stored in their prey. So, up to the end of the food chain, the energy has mostly worn out and become much less than that produced by plants at the very beginning.
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