GRE阅读高频机经原文及试题：海底火山生物

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GRE阅读高频机经原文及试题：海底火山生物

海底火山生物

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

Most deep-sea faunas rely for food on particulate matter, ultimately derived from photosynthesis, falling from above. The food supplies necessary to sustain the large vent communities, however, must be many times the ordinary fallout. 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. 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. This final observation seemed decisive. If such astonishing concentrations of bacteria were typical of vent outflow, then food within the vent would dwarf any contribution from advection. 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.

There are, however, certain difficulties with this interpretation. 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. This suggests that bacterial chemosynthesis is not a sufficient source of nutrition for these creatures. 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℃. No bacteria can survive such heat, and no bacteria were found there. Unless smokers are consistently located near more hospitable warm-water vents, chemosynthesis can account for only a fraction of the vent faunas. It is conceivable, however, that these large, sedentary organism 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.

Nonetheless advection is a more likely alternative food source. 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. Estimates suggest that for every cubic meter of vent discharge, 350 milligrams of particulate organic material would be advected into the vent area. Thus, for an average-sized vent, advection could provide more than 30 kilograms of potential food per day. 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.

32.1. the primary purpose of the passage is to

(A) describe a previously unknown natural phenomenon

(B) reconstruct the evolution of a natural phenomenon

学习啦在线学习网(C) establish unequivocally the accuracy of a hypothesis

(D) survey explanations for a natural phenomenon and determine which is best supported by evidence.

学习啦在线学习网(E) entertain criticism of the author’s research and provide an effective response

学习啦在线学习网32.2. which of the following does the author cite as a weakness in the argument that bacterial chemosynthesis provides the foundation for the food chains at deep-sea vents?

(A) vents are colonized by some of the same animals found in other areas of the ocean floor

学习啦在线学习网(B) vent water does not contain sufficient quantities of hydrogen sulfide.

(C) bacteria cannot produce large quantities of food quickly enough.

(D) large concentrations of minerals are found in vent water.

(E) some bacteria found in the vents are incapable of chemosynthesis

32.3. which of the following is information supplied in the passage that would support the statement that the food supplies necessary to sustain vent communities must be many times that of ordinary fallout?

(A) large vent faunas move from vent to vent in search of food

学习啦在线学习网(B) vent faunas are not able to consume food produced by photosynthesis.

(C) vents are more densely populated than are other deep-sea areas

32.4. the author refers to “smokers” (line 26) 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.

GRE阅读词汇精选之燃烧,烤

barbecue　n.烤肉架,烤肉

学习啦在线学习网baste　v.倒脂油于(烤肉上,以防烤干)

gridiron　n.烤架，橄榄球场

学习啦在线学习网grill　v.烤，· 烤问，· n.烤架

parch　v.烘烤，· 干热

学习啦在线学习网scorch　v.烤焦，· 烧焦

skewer　n.(烤肉用的)串肉杆　v.用杆串好

学习啦在线学习网broil　n/v　烤，· 烧，· 争吵，· 怒骂

学习啦在线学习网torrefy　v　焙，· 烤

学习啦在线学习网scathe　n.v.损害，· 烧焦

scorch　v.烤焦，· 烧焦

scorching　adj.酷热的

sear　v.(以烈火)烧灼

searing　adj.灼热的

学习啦在线学习网singe　v.(轻微地)烧焦，· 烫焦

学习啦在线学习网smolder　v.无火焰地闷烧，· 压抑

cauterize　vt　烧灼,使麻木不· 仁

学习啦在线学习网scald　v.烫，· 用沸水消毒　n.烫伤

学习啦在线学习网scalding　adj.滚烫的

combustible　adj.易燃的，· 易激动的

学习啦在线学习网combustion　n.燃烧

学习啦在线学习网flammable　adj.易燃的

ignite　v.发光，· 燃烧

inflame　v使燃烧，· 激怒(某人)

学习啦在线学习网inflammable　adj.可燃的，· 易激怒的

学习啦在线学习网kindle　v.着火、点燃

学习啦在线学习网rekindle　v.重新点燃

学习啦在线学习网enkindle　v.煽动,点燃(感情,怒气等)

nonflammable　adj.不· 易燃的

学习啦在线学习网stoke　v.添加燃料，· 司炉，· 吞食

学习啦在线学习网furnace　n.火炉,熔炉,磨练　v.　在炉中烧

学习啦在线学习网flask　n.烧瓶，· 细颈瓶

beaker　n.大酒杯，· 有倒口的烧杯

GRE阅读词汇精选之颜色

chromatic　adj.彩色的，五彩的

学习啦在线学习网prismy　adj　色彩缤纷的

学习啦在线学习网drab　adj.枯黄色的，无聊的

emerald　n.祖母绿,翡翠　　adj.翠绿色的

livid　adj.青灰色的(撞伤)，· (脸色)苍白的

magenta　n.adj.紫红色(的染料)

pallid　adj.苍白的，· 没血色的

florid　adj.华丽的，· (脸)红润的

rubicund　adj.(脸色)红润的

学习啦在线学习网ruddy　adj.(脸色)红润的，· 红色

学习啦在线学习网sable　n.黑貂，· 　　adj.黑色的

学习啦在线学习网sallow　n.柳树，· adj.病黄色的

sapphire　n.青玉，· 蓝宝石，· adj.天蓝色的.

学习啦在线学习网azure　adj.　天蓝色的　　n.碧空

学习啦在线学习网buff　n　浅黄色(软皮革)，· 水牛

lavender　n.　薰衣草　adj.　淡紫色的

学习啦在线学习网mulberry　n.　桑树，· 深紫红色

学习啦在线学习网cardinal　n.枢机主教,鲜红色　a.　主要的,深红色的

saffron　a.　番红花色的,橘黄色

patina　n.绿锈，· 光亮的外表

turquoise　n.绿松石，· adj.碧绿的

verdant　adj.青葱的，· 翠绿的

verdigris　n.铜锈，· 铜绿

hue　n.色彩，· 色泽

pastel　n.彩色粉笔画，· 柔和的色彩

学习啦在线学习网pigment　n.天然色素，· 干粉颜料

学习啦在线学习网tint　n.色彩,浅色　v.　染色于

学习啦在线学习网palette　n.调色板

学习啦在线学习网alabaster　a.雪白的

GRE阅读词汇精选之一群

学习啦在线学习网bevy　n.一群(少女或鸟)

学习啦在线学习网drove　n.畜群，人群

flock　n.羊群，鸟群

gaggle　n.鹅群

学习啦在线学习网herd　n.兽群v.聚集，放牧

horde　n.群众，一大群

学习啦在线学习网shoal　n.　程病　浅水处，一群(鱼)

swarm　n.(蜜蜂)一群，一群(人)

school　n　鱼群

flora　n.(某地区或时代的)植物群

fauna　n.动物区系

cluster　n.串，· 束，· 群，· v.成群，· 成串

学习啦在线学习网congregation　n.集合在一起的群众

constellation　n.星座，· 星群

galaxy　n.(银河)星群，· 显赫的人群

学习啦在线学习网archipelago　n.群岛

学习啦在线学习网gregarious　adj.群居的，· 爱社交的

legion　n.兵团，· 一大群

学习啦在线学习网ruck　n.皱褶，· 普通群众，· 大量

学习啦在线学习网throng　n.一大群，· v.拥挤

学习啦在线学习网menagerie　n　兽群，· 动物园

cline　n　渐变群,生态群

colony　n　[生]集群,群体

crew　n　全体人员,群众,全体机员

group　v　聚合,成群

exodus　v.大批离去,成群外出

异教徒

学习啦在线学习网heresy　n.异端邪说

heretic　n.异教徒

学习啦在线学习网heretical　adj.异端邪说的

heterodox　adj.异端的，非正统的

heterodoxy　n.异端邪说

学习啦在线学习网infidel　n.不信教者，异教徒

pagan　n.没有宗教信仰的人，异教徒

学习啦在线学习网paganism　n.异教(信仰)

heathen　n　异教徒，不信教的人

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