GRE阅读题目解析:深海动物群

　　P2

　　1

　　The deep sea typically has a sparse fauna dominated by tiny worms and crustaceans, with an even sparser distribution of larger animals.

　　一个典型的深海动物群是稀疏的，主要包括小虫和甲壳动物，更大型的动物则少之又少。

　　2

　　However, near hydrothermal vents, areas of the ocean where warm water emerges from subterranean sources, live remarkable densities of huge clams, blind crabs, and fish.

　　然而，海底喷泉口附近，也就热水从地表下喷出的区域，有大量巨型蛤蜊，盲蟹和鱼存活。

　　3

　　Most deep-sea faunas rely for food on particulate matter, ultimately derived from photosynthesis, falling from above.

　　多数深海动物的食物来源，是上方的光合作用产生的微粒物质的沉降。

　　4

　　The food supplies necessary to sustain the large vent communities, however, must be many times the ordinary fallout.

　　然而，大型海底喷口附近的动物对食物的需求，一定数倍于一般的沉降量。

　　5

　　The first reports describing vent faunas proposed two possible sources of nutrition: bacterial chemosynthesis, production of food by bacteria using energy derived from chemical changes, and advection, the drifting of food materials from surrounding regions.

　　描述喷口动物群的早期报告，提出两种可能的食物来源：细菌的化合作用，由利用化合作用所产生的能量的细菌来提供食物，和平流作用，由周围区域的海流循环运来食物。

　　6

　　Later, evidence in support of the idea of intense local chemosynthesis was accumulated: hydrogen sulfide was found in vent water; many vent-site bacteria were found to be capable of chemosynthesis; and extremely large concentrations of bacteria were found in samples of vent water thought to be pure.

　　后来，越来越多的证据，支持强烈的本地化学合成说：喷出的水流中检测出了硫化氢;很多喷口附近的细菌被发现能够进行化学合成;而在原以为纯净的喷口水样中，检测到了极高程度的细菌聚集。

　　7

　　This final observation seemed decisive.

　　最后这项观察结果看来是决定性的。

　　8

　　If such astonishing concentrations of bacteria were typical of vent outflow, then food within the vent would dwarf any contribution from advection.

　　如果喷口喷出的水都聚集了如此多的细菌，平流作用带来的那点食物简直无法和喷口本身提供的食物相提并论。

　　(dwarf 侏儒，作动词可以指 “通过比较使…显得矮小” 。

　　本剧直译大概是，喷口内的食物将使平流作用的的贡献显得矮小，也就说平流作用带来的食物相比之下太少了。)

　　9

　　Hence, the widely quoted conclusion was reached that bacterial chemosynthesis provides the foundation for hydrothermal - vent food chains - an exciting prospect because no other communities on Earth are independent of photosynthesis.

　　因此，细菌的化合为喷口附近区域的食物链提供了基础，成为一个广泛的共识 —— 这是个令人激动的观点，因为地球上其他群体的生存都不能脱离光合作用。

　　10

　　There are, however, certain difficulties with this interpretation.

　　然而，关于这种解释，仍有一些疑点。

　　11

　　For example, some of the large sedentary organisms associated with vents are also found at ordinary deep-sea temperatures many meters from the nearest hydrothermal sources.

　　比如，一些在喷口附近出现的大型固着生物，也在常温深海区域被发现，距离最近的喷发热源也有数米。

　　12

　　This suggests that bacterial chemosynthesis is not a sufficient source of nutrition for these creatures.

　　这意味着细菌化合不足以为这些动物提供食物。

　　13

　　Another difficulty is that similarly dense populations of large deep-sea animals have been found in the proximity of “smokers” – vents where water emerges at temperatures up to 350°C.

　　另一个难点在于，“smokers” 附近也发现了种群密度相似的大型深海动物，“smokers” 喷出的水温度高达 350 摄氏度。

　　14

　　No bacteria can survive such heat, and no bacteria were found there.

　　这种温度下不可能存活、也没有发现任何细菌。

　　15

　　Unless smokers are consistently located near more hospitable warm-water vents, chemosynthesis can account for only a fraction of the vent faunas.

　　除非 smokers 附近总有一些更适合动物生存的温水喷口，否则化学合成只能为一部分喷口附近的动物提供食物。

　　16

　　It is conceivable, however, that these large, sedentary organisms do in fact feed on bacteria that grow in warm-water vents, rise in the vent water, and then rain in peripheral areas to nourish animals living some distance from the warm-water vents.

　　尽管如此，可以想象，这些固着的大型动物实际上的确靠温水喷口的细菌提供食物，从喷口喷出的水最终回落到喷口周围，以养活喷口附近的动物。

　　17

　　Nonetheless, advection is a more likely alternative food source.

　　而平流作用，仍然更可能是另一种食物来源。

　　18

　　Research has demonstrated that advective flow, which originates near the surface of the ocean where suspended particulate matter accumulates, transports some of that matter and water to the vents.

　　已经有研究显示，海面附近出现的平流聚集了悬浮的颗粒物质，其中一部分随水流被运到喷口。

　　19

　　Estimates suggest that for every cubic meter of vent discharge, 350 milligrams of particulate organic material would be advected into the vent area.

　　据估算喷口喷出的每立方米水，会有350毫克有机颗粒物质会被洋流输送到附近区域。

　　20

　　Thus, for an average-sized vent, advection could provide more than 30 kilograms of potential food per day.

　　所以，一个中等大小的喷口，每天通过平流作用提供超过30千克潜在的食物。

　　21

　　In addition, it is likely that small live animals in the advected water might be killed or stunned by thermal and / or chemical shock, thereby contributing to the food supply of vents. (479 words)

　　另外，随着平流被带走的小动物也可能被热量 和 / 或 化学冲击杀死，因此增加了喷口的食物供应。

　　For the following question, consider each of the choices separately and select all that apply

　　5. The passage provides information for answering which of the following questions EXCEPT?

　　□A What causes warm-water vents to form?

　　□B What role does hydrogen sulfide play in chemosynthesis?

　　□C Do bacteria live in the vent water of smokers?

　　选 AB

　　A 温水喷口的成因是啥，不知道。

　　B 二氧化硫在化合过程中的作用是啥，不知道。

　　C smokers 喷出的水中有细菌吗，句 13、14 明确指出，不可能有，也没有发现过。

　　6. The information in the passage suggests that the majority of deep-sea faunas that live in nonvent habitats have which of the following characteristics?

　　(A) They do not normally feed on particles of food in the water.

　　(B) They are smaller than many vent faunas.

　　(C) They are predators.

　　(D) They derive nutrition from a chemosynthetic food source.

　　(E) They congregate around a single main food source.

　　选 B

　　根据句 1 、2，如果不是喷口附近的动物群(经常有大蛤蜊，盲鱼等)，普通的深海动物群，主要是虫子和甲壳动物，B 符合题干。

　　7. Select the sentence in the passage in which the author implies that vents are colonized by some of the same animal found in other areas of the ocean floor, which might be a weakness for the bacterial chemosynthesis model.

　　“ For example, some of the large sedentary organisms associated with vents are also found at ordinary deep-sea temperatures many meters from the nearest hydrothermal sources. ”

　　喷口是细菌最密集以及活跃的区域，也因此可以解释为许多动物提供了食物源，如果典型的喷口附近出现的大型动物也出现在较远的地区，则有可能削弱化合作用的理论模型。

　　如果仍然要坚持化合说，则起码要解释化合产物是如何被运输到数米以外的，像文中后面那样用平流作用来解释。

　　8. The author refers to "smokers" in the third paragraph most probably in order to

　　(A) show how thermal shock can provide food for some vent faunas by stunning small animals

　　(B) prove that the habitat of most deep-sea animals is limited to warm-water vents

　　(C) explain how bacteria carry out chemosynthesis

　　(D) demonstrate how advection compensates for the lack of food sources on the seafloor

　　(E) present evidence that bacterial chemosynthesis may be an inadequate source of food for some vent faunas

　　选 E

　　smokers 的特点是温度特别高，细菌不可能在这种高温环境下生存，所以提出 smokers 是为了说明，单纯用细菌化合说解释不了所有的 vent faunas 。

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