Lecture 3 微生物群
Wors Tips
bacteria n.细菌 organic adj.有机的；有机物的
inorganic adj.无生物的；无机的 molecule n.分子；微粒
photosynthesis n.光合作用 microbe n.微生物
microorganisms n.微生物 secrete v.分泌；隐藏
quiz n.小测验 hydrothermal adj.热水（作用）的
vent n.（空气、气体、液体的）出口 vessel n.大船；轮船
existence n.存在
chemosynthetic adj.〔生〕化能合成的；化学合成的
Listen to the following recording and answer questions 1-4.
1）A.To show how the exploration helped researchers determine the composition of ocean water.
B.To show how the exploration challenged an assumption about biological communities.
C.To compare two competing theories concerning chemosynthesis.
D.To compare the life cycle of underwater plants to the life cycle of underwater animals.
2）A.lack of sunlight，extreme heat and pressure
B.Lack of minerals，extreme cold and fast currents.
C.Lack of food，extreme depth and pressure
D.Lack of energy，bad quality of water and too many chemicals
3）A.They were surprised at the large variety of organisms living near hydrothermal vents.
B.They were surprised to find any bacteria living without sunlight.
C.They were disappointed at not finding any animal life.
D.They could not agree on the significance of the data that they collected.
4）A.the sunlight
B.the chemical reactions
C.the body of dead animals
D.the water heat and pressure
听力原文
Professor：OK.We’ve been talking till now about the two basic needs of a biological community，an energy source to produce organic materials，you know，ah，food for the organisms，and the waste recycling or breakdown of materials back into inorganic molecules，and about how all this requires photosynthesis when green plants or microbes convert sunlight into energy and also requires microorganisms，bacteria，to secrete chemicals that break down or recycle the organic material to complete the cycle.So，now we are done with this chapter of the textbook，we can just review for the weekly quiz and move on to the next chapter，right？ Well，not so fast.First，I’d like to talk about some discoveries that have challenged one of these fundamental assumptions about what you need in order to have a biological community.And，well，there actually were quite a few surprises.It all began in 1977 with the exploration of hydrothermal vents on the ocean floor.Hydrothermal vents are cracks in the Earth’s surface that occur，well，the ones we are talking about here are found deep at the bottom of the ocean.And these vents on the ocean floor，they release this incredibly hot water，3-4 times the temperature that you boil water at because this water has been heated deep within the Earth.Well about 30 years ago，researchers sent a deep-sea vessel to explore the ocean’s depth，about 3 kilometers down，way deep to the ocean floor.No one had ever explored that far down before.Nobody expected there to be any life down there because of the conditions.First of all，sunlight doesn’t reach that far down so it’s totally dark.There couldn’t be any plant or animal life since there’s no sunlight，no source of energy to make food.If there was any life at all，it’d just be some bacteria breaking down any dead materials that might have fallen to the bottom of the ocean.And not only the extreme pressure，but also the extreme temperature of the water around these vents.If the lack of sunlight didn’t rule out the existence of a biological community down there then these factors certainly would，or so they thought.
Student：So you are telling us they did find organisms that could live under those conditions？
Professor：They did indeed，something like 300 different species.
Student：But… but how could that be？ I mean without sunlight，no energy，no no …
Professor：What they discovered was that microorganisms，bacteria，had taken over both functions of the biological community - the recycling of waste materials and the production of energy.They were the energy source.You see，it turns out that certain microorganisms are chemosynthetic.They don’t need sunlight because they take their energy from chemical reactions.
Questions：
1.Why does the professor discuss the exploration of hydrothermal vents？
2.What are three of the conditions of water near hydrothermal vents that made researchers think they would not find living organisms there？
3.What does the professor imply about the researchers’ reaction to the biological community discovered on the ocean floor？
4.Where do the microorganisms take their energy from according to scientists？
参考译文
教授：好了。我们一直在讲生物群体的两种基本需求——产出有机物质的能量来源，你们知道的，生物的食物，以及废物回收或者物质分解成无机分子，以及当绿色植物或者微生物将阳光转化为能源时，所有这些都需要光合作用，还需要微生物、细菌来分泌化学物质来分解或者再循环这些有机物质，来完成循环。那么，现在我们完成了教科书上这章的内容了，我们能为周测验开展复习，然后进入下一单元了，是吧？嗯，还没有这么快。首先我来讲一些发现，这些发现挑战了生物群体基本需求的其中一个基本假设。而且，事实上有很多让人感到惊奇的地方。一切始于1977年的一次海底深海热泉的探索。深海热泉是地球表面存在的裂缝，我们说的这个就是在海底的裂缝。这些海底的出口，排出极其热的水，温度比开水还要高3到4倍，因为这些水是从地球内部加热的。大概30年前，研究人员派出了一个深海船来探察海洋深度，到海洋底部大约是3千公里深，之前从来没有人到如此的深度来探索过。由于下面的这种环境，没有人想过下面会有生命。首先，阳光不能到达那么远，因此下面是漆黑一片。也不可能有任何动植物，因为那里没有阳光，没有能源来提供食物。如果有生命的话，也就是一些分解任何死去物质的细菌可能跌落至海洋底层。这里不仅压强极大，而且出口附近水温极高。如果阳光的缺失没有使这里的生物群体消失的话，那么这些因素也会的，人们起初这么想。
学生：那么你是在说他们在那种环境下找到有机物了？
教授：确实。找到了大概300个不同物种。
学生：但是那怎么可能呢？我的意思是说没有阳光，没有能源，没有……
教授：他们找到的是有两种生物群体功能的微生物——细菌，担负起了生物群体生存必需的两个要素的责任：废物循环及能源再生。他们就是能源。你们看，原来有些微生物是化学合成的，他们不需要阳光，因为他们从化学作用中吸取能源。
参考答案
1.B 2.A 3.A 4.B