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

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

(C) establish unequivocally the accuracy of a hypothesis

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

(E) entertain criticism of the author’s research and provide an effective response

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

(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

(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

baste　v.倒脂油于(烤肉上,以防烤干)

gridiron　n.烤架，橄榄球场

grill　v.烤，· 烤问，· n.烤架

parch　v.烘烤，· 干热

scorch　v.烤焦，· 烧焦

skewer　n.(烤肉用的)串肉杆　v.用杆串好

broil　n/v　烤，· 烧，· 争吵，· 怒骂

torrefy　v　焙，· 烤

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

singe　v.(轻微地)烧焦，· 烫焦

smolder　v.无火焰地闷烧，· 压抑

cauterize　vt　烧灼,使麻木不· 仁

scald　v.烫，· 用沸水消毒　n.烫伤

scalding　adj.滚烫的

combustible　adj.易燃的，· 易激动的

combustion　n.燃烧

flammable　adj.易燃的

ignite　v.发光，· 燃烧

inflame　v使燃烧，· 激怒(某人)

inflammable　adj.可燃的，· 易激怒的

kindle　v.着火、点燃

rekindle　v.重新点燃

enkindle　v.煽动,点燃(感情,怒气等)

nonflammable　adj.不· 易燃的

stoke　v.添加燃料，· 司炉，· 吞食

furnace　n.火炉,熔炉,磨练　v.　在炉中烧

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

prismy　adj　色彩缤纷的

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

ruddy　adj.(脸色)红润的，· 红色

sable　n.黑貂，· 　　adj.黑色的

sallow　n.柳树，· adj.病黄色的

sapphire　n.青玉，· 蓝宝石，· adj.天蓝色的.

azure　adj.　天蓝色的　　n.碧空

buff　n　浅黄色(软皮革)，· 水牛

lavender　n.　薰衣草　adj.　淡紫色的

mulberry　n.　桑树，· 深紫红色

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

pigment　n.天然色素，· 干粉颜料

tint　n.色彩,浅色　v.　染色于

palette　n.调色板

alabaster　a.雪白的

GRE阅读词汇精选之一群

bevy　n.一群(少女或鸟)

drove　n.畜群，人群

flock　n.羊群，鸟群

gaggle　n.鹅群

herd　n.兽群v.聚集，放牧

horde　n.群众，一大群

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

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

archipelago　n.群岛

gregarious　adj.群居的，· 爱社交的

legion　n.兵团，· 一大群

ruck　n.皱褶，· 普通群众，· 大量

throng　n.一大群，· v.拥挤

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

heresy　n.异端邪说

heretic　n.异教徒

heretical　adj.异端邪说的

heterodox　adj.异端的，非正统的

heterodoxy　n.异端邪说

infidel　n.不信教者，异教徒

pagan　n.没有宗教信仰的人，异教徒

paganism　n.异教(信仰)

heathen　n　异教徒，不信教的人

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