托福听力资料托福tpo15听力文本 (2)

【托福听力资料】托福TPO15 听力文本-Lecture 4

众所周知，托福TPO材料是备考托福听力最好的材料。相信众多备考托福的同学也一直在练习这套材料，那么在以下内容中我们就为大家带来托福TPO听力练习的文本，希望能为大家的备考带来帮助。

TPO 15 Lecture 4 Biology

Narrator: Listen to part of a lecture in a biology class.

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 uh, 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

taiking 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 to 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?

Student 1 ：And what about the water pressure? Didn ’ t we talk before about how the deeper down into the ocean you go, the greater the pressure? Professor ：Excellent point! 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 2：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 1 ：But... but how could that be? I mean without sunlight, no energy,