托福閱讀TPO33(試題+答案+翻譯)第3篇:滅絕事件
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托福閱讀TPO33閱讀原文
Extinction Episodes of the Past
【1】It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. Since the Cambrian period, biodiversity has generally risen, but there have been some notable exceptions. Biodiversity collapsed dramatically during at least five periods because of mass extinctions around the globe. The five major mass extinctions receive most of the attention, but they are only one end of a spectrum of extinction events. Collectively, more species went extinct during smaller events that were less dramatic but more frequent. The best known of the five major extinction events, the one that saw the demise of the dinosaurs, is the Cretaceous-Tertiary extinction.
【2】Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this was the era “when dinosaurs ruled Earth,” when a wide variety of reptile species occupying many ecological niches. However, no group or species can maintain its dominance indefinitely, and when, after over 200 million years, the age of dinosaurs came to a dramatic end about 65 million years ago, mammals began to flourish, evolving from relatively few types of small terrestrial animals into the myriad of diverse species, including bats and whales, that we know today. Paleontologists label this point in Earth’s history as the end of the Cretaceous period and the beginning of the Tertiary period, often abbreviated as the K-T boundary. This time was also marked by changes in many other types of organisms. Overall, about 38 percent of the families of marine animals were lost, with percentages much higher in some groups Ammonoid mollusks went from being very diverse and abundant to being extinct. An extremely abundant set of planktonic marine animals called foraminifera largely disappeared, although they rebounded later. Among plants, the K-T boundary saw a sharp but brief rise in the abundance of primitive vascular plants such as ferns, club mosses, horsetails, and conifers and other gymnosperms. The number of flowering plants (angiosperms) was reduced at this time, but they then began to increase dramatically.
【3】What caused these changes? For many years scientists assumed that a cooling of the climate was responsible, with dinosaurs being particularly vulnerable because, like modern reptiles, they were ectothermic (dependent on environmental heat, or cold-blooded). It is now widely believed that at least some species of dinosaurs had a metabolic rate high enough for them to be endotherms (animals that maintain a relatively consistent body temperature by generating heat internally). Nevertheless, climatic explanations for the K-T extinction are not really challenged by the ideas that dinosaurs may have been endothermic, because even endotherms can be affected by a significant change in the climate.
【4】Explanations for the K-T extinction were revolutionized in 1980 when a group of physical scientists led by Luis Alvarez proposed that 65 million years ago Earth was stuck by a 10-kilometer-wide meteorite traveling at 90,000 kilometers per hour. They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions. Initially, the meteorite theory was based on a single line of evidence. At locations around the globe, geologists had found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. Iridium is an element that is usually uncommon near Earth’s surface, but it is abundant in some meteorites. Therefore, Alvarez and his colleagues concludedthat it was likely that the iridium in sedimentary rocks deposited at the K-T boundary had originated in a giant meteorite or asteroid. Most scientist came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.
托福閱讀TPO33閱讀試題
1.The word "proliferation" in the passage (paragraph 1) is closest in meaning to
A.decline.
B.extinction.
C.increase.
D.migration.
2.Paragraph 1 supports which of the following statements about life on Earth before the Cambrian period?
A.Biodiversity levels were steady, as indicated by the fossil record.
B.Levels of biodiversity could not be tracked.
C.The most dramatic extinction episode occurred.
D.Few microscopic species existed.
3.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A.The dominance of dinosaurs came to an end 65 million years ago, at which time mammals began to flourish and diversify.
B.Because no group of species can remain dominant forever, mammals became the dominant group when dinosaurs became extinct.
C.After being the dominant group for more than 200 million years, the age of dinosaurs came to a dramatic end 65 million years ago.
D.The diverse group of mammals that we know today, including bats and whales, evolved from small terrestrial forms that had been dominated by dinosaurs.
4.According to paragraph 2, why are dinosaurs popularly said to have "ruled Earth" during the Cretaceous period?
A.Dinosaurs were the only species of reptile that existed during the whole of the Cretaceous period.
B.Dinosaurs won the battle for food resources over mammals during the Cretaceous period.
C.Dinosaurs survived extinction during the Cretaceous period, whereas many other animal species did not.
D.Dinosaurs were the physically and ecologically dominant animals during the Cretaceous period.
5.According to paragraph 2, which of the following species initially increased in number at the K-T boundary?
A.Dinosaurs.
B.Foraminifera.
C.Ferns.
D.Ammonoid mollusks.
6.Why does the author note that "even endotherms can be affected by a significant change in the climate"(paragraph 3)?
A.To argue that there was a significant climate at the time that endothermic dinosaurs became extinct.
B.To argue that climate change caused some dinosaurs to evolve as endotherms.
C.To support the view that at least some of the dinosaurs that became extinct were endotherms.
D.To defend climate change as possible explanation for the extinction of dinosaurs.
7.The word "generated"(paragraph 4) in the passage is closest in meaning to
A.collected.
B.produced.
C.spread.
D.added.
8.The word "extensive"(paragraph 4) in the passage is closest in meaning to
A.widespread.
B.sudden.
C.numerous.
D.subsequent.
9.According to paragraph 4, all of the following contributed to the massive extinctions of the K-T period EXCEPT:
A.tidal waves.
B.fires.
C.insufficient solar radiation.
D.iridium.
10.According to paragraph 4, which of the following statements explains the importance of the discovery of high levels of iridium rocks?
A.It provided evidence that overexposure to solar radiation led to the K-T extinction.
B.It showed that more than one cataclysmic event was responsible for the K-T extinction.
C.It suggested that the cause of the K-T extinction may have been a meteorite striking Earth.
D.It provided evidence that the K-T extinction occurred 65 million years ago.
11.According to paragraph 4, which of the following is true about the Yucatan Peninsula?
A.The circular formation there was caused by a meteorite impact 65 million years ago.
B.Sedimentary rocks from that area have the lowest iridium concentration of any rocks on Earth.
C.There is evidence that a huge tidal wave occurred there 65 million years ago.
D.Evidence found there challenged the meteorite impact theory.
12.Which of the following can be inferred from paragraph 4 about the meteorite theory?
A.The data originally presented as evidence for the theory were eventually rejected.
B.Many scientists did not accept it when it was first proposed.
C.It has not been widely accepted as an explanation for the K-T extinction.
D.Alvarez subsequently revised it after a circular formation was found in the Yucatan Peninsula.
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? This focused on the chemical composition of ancient rocks.
Explanations for the K-T extinction were revolutionized in 1980 when a group of physical scientists led by Luis Alvarez proposed that 65 million years ago Earth was stuck by a 10-kilometer-wide meteorite traveling at 90,000 kilometers per hour. They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions. ■【A】Initially, the meteorite theory was based on a single line of evidence. ■【B】At locations around the globe, geologists had found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. ■【C】Iridium is an element that is usually uncommon near Earth's surface, but it is abundant in some meteorites. ■【D】Therefore, Alvarez and his colleagues concluded that it was likely that the iridium in sedimentary rocks deposited at the K-T boundary had originated in a giant meteorite or asteroid. Most scientist came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.
14. Prose Summary
The K-T extinction 65 million years ago is the best known of the five major extinction episodes since the Cambrian period.
A.Collectively, the five major extinction episodes resulted in the elimination of a larger number of species than did all the minor extinction events.
B.The K-T extinction eliminated the dinosaurs and ammonoid mollusks but was followed by the diversification of mammals and gymnospermous plants.
C.An extreme cooling of the climate could not have caused the K-T extinction of dinosaurs, because, while most dinosaurs depended on environmental heat, some did not.
D.The K-T extinction of the dinosaurs is the only mass extinction that has been explained by the impact of a meteorite.
E.In 1980 Luis Alvarez proposed that the K-T extinction was caused by ecological disasters brought about by the impact of a meteorite striking Earth.
F.A high concentration of iridium in sedimentary rocks at the K-T boundary and a large impact crater in the Yucatan Peninsula from 65 million years ago strongly support Alvarez' hypothesis.
托福閱讀TPO33閱讀答案
1.proliferation，繁殖，激增，對(duì)應(yīng)C。
2.推斷題：定位句It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity.主要意思是直到寒武紀(jì)才能夠監(jiān)測(cè)生物多樣性。言外之意就是在寒武紀(jì)之前就不能監(jiān)測(cè)生物多樣性，對(duì)應(yīng)B選項(xiàng)。
3.解析句子簡(jiǎn)化題：該長句其實(shí)是2個(gè)長句的并列;主要分成2個(gè)意思：第一是沒有任何一種生物能永遠(yuǎn)地統(tǒng)治，第二是恐龍滅亡之后，哺乳動(dòng)物開始發(fā)展統(tǒng)治，且兩層意思之間可以構(gòu)成因果關(guān)系。所以只有B選項(xiàng)滿足所有條件。
4.解析細(xì)節(jié)題：定位句Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this was the era "when dinosaurs ruled Earth," when a wide variety of reptile species occupying many ecological niches.對(duì)應(yīng)D選項(xiàng)。
5.解析細(xì)節(jié)題：定位句Paleontologists label this point in Earth's history as the end of the Cretaceous period and the beginning of the Tertiary period，often abbreviated as the K-T boundary. This time was also marked by changes in many other types of organisms. Overall, about 38 percent of the families of marine animals were lost, with percentages much higher in some groups
Ammonoid mollusks went from being very diverse and abundant to being extinct.題干中的范圍限定initially，因此只可能是Ammonoid mollusk.選D。
6.解析修辭目的題：題干中的even甚至，表示程度的遞進(jìn)。定位句Nevertheless, climatic explanations for the L-T extinction are not really challenged by the ideas that dinosaurs may have been endothermic。即后半句的原因解釋了氣候理論為什么不被反駁。
7.generate，產(chǎn)生，選B。
8.extensive，廣泛的，選A。
9.解析否定細(xì)節(jié)題：定位句 Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions.對(duì)應(yīng)A選項(xiàng)，B選項(xiàng)。定位句 They believed that its impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels.意思是這種沖擊產(chǎn)生了大量的厚塵云，遮蔽了天空和陽光。對(duì)應(yīng)C選項(xiàng)。而D選項(xiàng)，iridium是有關(guān)滅絕的證據(jù)，但并非構(gòu)成滅絕的原因。
10.解析細(xì)節(jié)題：定位句Initially, the meteorite theory was based on a single line of evidence. At locations around the globe, geologists have found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago.意思是說小行星撞擊理論一開始主要的證據(jù)就 是在地球的巖石中發(fā)現(xiàn)了大量的iridium (銥)。因此其重要性就是說明該撞擊理論是物種大滅絕的原因。
11.解析細(xì)節(jié)題：定位句Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.意思是說在Yucatan Peninsula背岸的大坑是隕石撞擊的結(jié)果。對(duì)應(yīng)A選項(xiàng)。
12.解析推斷題：定位句 Initially, the meteorite theory was based on a single line of evidence. 一開始僅依賴于單一證據(jù)的理論，暗示了證據(jù)還不夠充分。定位句 Most scientists came to accept the meteorite theory after evidence came to light that a circular formation，180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.在環(huán)形坑證據(jù)出現(xiàn)之后大多數(shù)的科學(xué)家才開始接受小 行星撞擊理論，就是說一開始大多數(shù)科學(xué)家對(duì)該理論是持有懷疑態(tài)度的。即答案就是B。
13.解析句子插入題：給出的句子中出現(xiàn)了this的指代提示，表示前面的內(nèi)容可能 與石頭的化學(xué)組成無關(guān)，而該句的下一句應(yīng)該與化學(xué)組成有關(guān)。因此只有 第二個(gè)方框滿足條件。在第二個(gè)方框之后才出現(xiàn)了對(duì)于iridium的討論。
14.The K-T extinction eliminated the dinosaurs and ammonoid mollusks but was followed by the diversification of mammals and gymnospermous plants.正確。對(duì)應(yīng)第二段段落大意，沒有永生的統(tǒng)治者，恐龍之后現(xiàn)在是哺乳動(dòng)物和植物的天下。
In 1980 Luis Alvarez proposed that the K-T extinction was caused by ecological disasters brought about by the impact of a meteorite striking Earth.正確。對(duì)應(yīng)第四段主旨：小行星撞擊地球假說。
A high concentration of iridium in sedimentary rocks at the K-T boundary and a large impact crater in the Yucatan Peninsula from 65 million years ago strongly support Alvarez, hypothesis.正確。對(duì)應(yīng)第四段解釋小行星撞擊地球假說的重要證據(jù)。一個(gè)證據(jù)是Iridium在 地球巖石中的大量出現(xiàn)，另一個(gè)證據(jù)是巨大環(huán)形坑的發(fā)現(xiàn)。
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