2015年7月11日托福听力真题原文+题目+答案+mp3下载：zooplankton

2015年7月11日托福听力真题原文+题目+答案+mp3下载：zooplankton

听力原文如下：

The sea is teeming with tiny organisms but they don't get as much popular attention as say whales. Microscopic algaes aren't just so exciting, I suppose, and yet those organisms are the foundation of bulk of marine food chain. Without plankton, which is a global term for those tiny organisms, there will be no whales. Plankton is found both in fresh water and marine environments. Again it is a term used for any small organisms that float along with the current, either because they are too small or weak to swim against it or because they don't have any capacity at all to move by themselves. Plants and plant-like plankton are called phytoplankton, while animals and animal-like plankton are called zooplankton. For over a century now, researchers have been trying to solve the mysteries about the zooplankton. You see, since species of zooplanktons migrate, er ... not as the birds do when the seasons change, but daily, in a phenomenon called diel-vertical migration or DVM.

In the diel-vertical migration, zooplankton swim up onto the surface of water during the night, and swim down to deep water during the day. Depending on the species and region, this can be a round trip between 100 and 400 meters. For a tiny microscopic organism, that is a huge distance. (2)Remember now, zooplankton can't swim very well, and IDVM requires a lot of energy. So there must be important benefit to this daily up and down commuting. We're not exactly sure about what the benefit is, though there are several compelling theories. I will talk about them in a moment, but first, I want to talk about what we do know, or rather what we are pretty sure we know. So researchers generally agree the stimulus for zooplanktons' DVM is light, zooplanktons 。。。。余下听力原文省略!

听力真题题目如下：

1..What does the professor mainly discuss

A、The importance of zooplankton in the marine food chain

B、The interdependence of two types of tiny marine organisms

C、Aphysical feature of zooplankton that makes them well adapted for swimming

D、A phenomenon observed in some species of zooplankton

2 Why does the professor conclude that zooplankton must derive an important benefit from diel vertical migration

A、Dielvertical migration uses up a lot of energy.

B、Diel vertical migration exposes zooplankton to predators.

C、Diel vertical migration prevents zooplankton from being a0le to digest phytoplankton.

D、Diel vertical migration forces zooplankton populations to live permanently in cold water.

。。。。余下听力真题题目及答案省略！

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