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2010年10月17日托福机经英文版原文

2012-01-19 00:00     作者 :    

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  生活在寒冷海底的生物
通常認為在寒冷和高壓的深海是沒有生物,或是體型較小的生物。但是發現寒冷海底生物體型很大(三個原因:食物充足,無年輕個體,競爭少),而且發現了一種之前認為滅絕了的遠古生物。此外還提到了海底的細菌,可以承受高壓。
深海魚類
過去科學家以為深海沒有生命體。不過自從193X年一隻大型生物在印度洋被抓上岸之後,科學家發現深海生物其實很豐富,大型生物更不在少數。
人類開始時認為深海的海底只有些小魚小蝦們,直到後來又發現了什麼魚。這種魚類原本生物學家們認為已經滅絕了,後來竟然又被發現了,這讓他們很吃驚(這句話被highlight了,問同義句)。原來深海底有大魚,而且這些魚群往往很龐大,說了三點原因:海底食物充足,無年輕個體,競爭少(except題,問哪個選項不是魚群龐大的原因,選游得很快)。
文章繼續說海底發現了很多古代魚類,舉了幾個古魚的例子(說了一串,只記住了一個starfish in the Arctic Ocean,有題問其中一個魚能infer什麼,應該是選他是屬於一種很古老的魚類)。這些魚在海底可以承受很大的壓力,most of them 一游到淺海地區就會死,但是有些Arctic Ocean的魚還可以游到surface上來。
下一段說這個深海不但水壓大,而且還非常的寒冷freezing,但是這群深海魚的blood有個特點,可以抗凍,這個特質可以使它們抵禦深海的寒冷(有題,問為什麼,就選blood那個),然後文章又提了Antarctic Ocean,這個Antarctic更厲害,比Arctic還冷,但是Antarctic依然物產豐富(有題)占了全ocean的2/3。但由於這裏太冷了,Antarctic裏面魚的種類仍然不到Arctic的1/2。
辭彙題:
allocation = distribution
previously = formerly
bizarre = very strange
insight into = understanding of
manner
fragile
stimulate
Explore the Deep Sea life 探索海底生物
Before the first dives to mid-ocean ridges in the late 1970s, researchers expected to encounter a barren, mostly lifeless landscape. Algae and plants cannot survive without sunlight, which does not penetrate ocean water below about 1000 meters. Without plants or algae to form the base of the food chain, how could there be much to eat apart from a sparse sprinkling of "marine snow"—the corpses of animals and plants which died nearer the surface? But patches around active volcanoes and vents teem with life.
Living without sunlight
Some animals found around vents get their food by eating other organisms. But many of the animals living near deep-sea vents obtain their food in a very different way: they play host to particular species of microbe that live inside their bodies and manufacture food by combining certain chemicals found in vent fluids with oxygen found in seawater. The microbes give some of the food they manufacture to their animal hosts.
Hostile conditions
Organisms living near deep-sea vents have to be able to tolerate or avoid the extreme conditions there. The pressure is immense—hundreds of times greater than that at the ocean surface. The ocean water is just a few degrees above freezing, but fluids jetting out of seafloor vents can be tens or hundreds of degrees hotter. Many of the chemicals in the vent fluid are extremely toxic, even at low concentrations.
New species galore
Mussels, shrimp, crabs, snails, fish, huge worms and many other lifeforms have been discovered since the first dives to vents on the ocean floor. Most of these organisms were new to science, and to this day many new species are discovered each year.
Where (and when) you are determines what creatures you find
Different oceans contain different species. For example, deep-sea vent sites in the Atlantic contain many shrimps and mussels, whereas sites in the East Pacific have abundant tubeworms and clams as well as mussels. The depth and composition of the water also affects which species we see, as does the age of the site. Volcanic areas are often extremely dynamic. Vents can form suddenly when the crustal rocks crack, and die some time later (e.g. as the crack gets plugged with rock). Some vents are long-lived and others are short-lived. Some vents blow extremely hot fluid, while others merely seep warm fluid. The chemistry of the fluid exiting the vent varies—some vents contain more toxic chemicals than others. This variation in space and time creates a rich variety of habitats for vent creatures.
Life away from vents
Away from vents, the deep ocean is far from barren, and certain patches are especially rich in life. For example, whale carcasses support a wide range of organisms, including some that are closely related to vent species. Deep-water corals also function as essential habitats for a wide range of other creatures; they are found at depths down to about 2000m

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