考满分 toefl

1 .Listen to part of a lecture in a biology class.

听一段生物学课上的讲座片段。

1 .P: Okay, your reading homework for class today took a brief look at how life forms adapt to their environment, and I want to get deeper into that today. Yes, Mark?

教授： 好的，你们今天这节课的阅读作业，简要探讨了生物如何适应环境，今天我想深入讲解一下。马克？

2 .S: Professor, I have a question about part of the reading. One of the chapters was about how seawater has influenced the evolution of marine organisms, right? Well, there was a section about filter feeders? P: Yes.

学生： 教授，我对阅读材料的某一部分有个问题。其中一章讲到海水是如何影响海洋生物进化的，对吧？里面有一部分关于滤食动物？ 教授：是的。

3 .S: The book said that filter feeders eat by straining food particles from the water, right? P: Right.

学生： 书上说滤食动物通过从水中过滤食物颗粒来进食，对吧？ 教授： 对。

4 .S: Well, maybe this seems kind of obvious, but why aren't there any filter feeders on land? Or are there? The book didn't say.

学生： 嗯，这可能是显而易见的，但为什么陆地上没有滤食动物？或者说有吗？书上没说。

1 .P: No, it didn't. Does anyone want to guess? No? Well, maybe it's not so obvious. Okay, then, first, seawater is almost 1000 times more dense than air, so relatively large particles and organisms can stay buoyant or suspended. And because of this, there is a major marine ecosystem of small organisms called plankton that are perpetually suspended in seawater from the top to the bottom. Plankton can be plants, animals, or even certain kinds of bacteria.

教授： 是的，确实没说。有人想猜猜吗？没有？好吧，也许这并不那么显而易见。那么，首先，海水的密度几乎是空气的1000倍，所以相对较大的颗粒和生物可以保持漂浮或悬浮状态。因此，从上到下海水中有一个主要的海洋生态系统，称为浮游生物的群体，它们永远悬浮在海水中。浮游生物可以是植物、动物，甚至某些种类的细菌。

2 .In fact, any of the small drifting life forms in bodies of water, such as oceans, seas, and lakes, can be called plankton, and it's the primary food source for some of the smallest and some of the largest animals in the oceans, the so-called filter feeders. These filter feeders have adapted over time and have developed specialized structures to extract plankton and other food particles that float around in the ocean.

事实上，任何在水体（如大洋、海和湖泊）中漂流的小型生命形式都可以称为浮游生物，而且它是海洋中一些最小动物和最大动物的主要食物来源，这些动物就是所谓的滤食动物。这些滤食动物随着时间的推移适应并演化出专门的结构来从海洋中提取浮游生物和其他食物颗粒。

1 .S: And that's where the baleen comes in, right? P: Oh, yes, baleen is what several species of whale have. They have baleen instead of teeth , and what a baleen is? Well, it's made of long plates, long plates that are composed of a tough protein called keratin. The edges of these keratin plates have fringes almost like hairs that hang down and act as a strainer. So what happens is that a baleen whale takes in a huge amount of water full of plankton and other small organisms into its mouth, and then pushes the water out through the baleen fringes, which filters out the plankton so the whale can eat it.

学生：这就是鲸须的作用，对吧？ 教授：哦，是的，鲸须是一些种类的鲸鱼所拥有的。它们没有牙齿，而是有鲸须，那么鲸须是什么呢？鲸须是由长的板状物组成的，这些板状物由一种坚韧的蛋白质——角质蛋白组成。这些角蛋白板的边缘有几乎像毛发一样的流苏，起到过滤器的作用。所以，鲸须鲸会吸入大量充满浮游生物和其他小生物的水，然后通过鲸须流苏将水推出，从而过滤出浮游生物，使鲸能吃掉它们。

2 .And then there are sessile filter feeders. Sessile filter feeders stay in one place. They don't swim around like whales do. So while baleen whales can go to places where there's a lot of food, sessile filter feeders, like sponges, stay in one place and thrive because the currents bring food to them.

还有一种是固着滤食动物。固着滤食动物停留在一个地方。它们不像鲸鱼那样游动。所以，虽然须鲸可以去有很多食物的地方，但像海绵动物这样的固着滤食动物，会留在一个地方并且茁壮生长，因为洋流会把食物带给它们。

3 .S: So how are the sponges specially adapted to filter feed?

学生：那么海绵是如何适应滤食的呢？

4 .P: In a way, the whole sponge is a filter. Sponges are generally chimney shaped, and they have special cells that draw in water and food particles through small holes in their walls. They have other cells that trap and digest the food particles and yet others that move nutrients throughout the sponge. Filtered water and waste are expelled through the big hole in the top of the sponge.

教授：从某种角度看，整个海绵都是一个过滤器。海绵通常呈烟囱形状，它们有专门的细胞通过墙上的小孔吸入水和食物颗粒。它们还有其他细胞用来捕捉和消化食物颗粒，还有一些细胞则将营养物质输送到整个海绵。过滤后的水和废物从海绵顶部的大孔中排出。

1 .S: Okay, so what it comes down to is that there is nothing like plankton living in the air. So no land animals have evolved that filter the air for food.

学生：好的，那么总结下来就是，空气中没有类似浮游生物的东西。因此没有陆地动物进化出过滤空气以获取食物的方式。

2 .P: Right, now there are some birds, like flamingos, that are filter feeders, but flamingos filter their food from water, not the air. The closest thing to a filter feeder on land are spiders, but they're not actually filtering the air for food either.

教授：对，现在确实有一些鸟类，比如火烈鸟，它们是滤食动物，但火烈鸟是从水中过滤食物，而不是从空气中。陆地上最接近滤食动物的可能是蜘蛛，但它们实际上也不是从空气中过滤食物。