Question

The evolution of the first animals may have oxygenated（供氧）Earth's oceans. New research

led by the University of Exeter challenges the long held belief that oxygenation of the atmosphere and oceans was a precondition for the evolution of complex life forms.

The study, published in the journal Nature Geoscience, builds on the recent work of scientists in Denmark who found that sponges（海綿動物）一the first animals to evolve一require only small amounts of oxygen.

Professor Tim Lenton of the University of Exeter, who led the new study, said: "We argue that the evolution of the first animals could have played a key role in the widespread oxygenation of the deep oceans. This in turn may have facilitated the evolution of more complex, mobile animals."

Critical to determining oxygen levels in the deep ocean is the balance of oxygen supply and demand. Demand for oxygen is created by the sinking of dead organic material into the deep ocean. The new study argues that the first animals reduced this supply of organic matter一both directly and indirectly.

Sponges feed by pumping water through their bodies, "digesting" the tiny particles of organic matter, and thus helping oxygenate the shelf seas that they live in. By oxygenating more of the bottom waters, the first animals actually increased the removal of the essential nutrient phosphorus（磷）in the ocean. This in turn reduced the productivity of the whole ocean ecosystem, lowering oxygen demand and thus oxygenating the deep ocean.

A more oxygen-rich ocean created ideal conditions for more complex mobile animals to evolve, because they have a higher requirement for oxygen. These included the first predatory（肉食的）animals with guts（內(nèi)臟）that started to eat one another, marking the beginning of the type of food webs we are familiar with today.

Professor Simon Poulton of the University of Leeds, who is a co-author of the study, added: "This study provides a possible mechanism for ocean oxygenation without the requirement for a rise in atmospheric oxygen. It therefore questions whether the long-standing belief that there was a major rise in atmospheric oxygen at this time is correct. We simply don't know the answer to this at present, which is ultimately key to understanding how our planet evolved to its current habitable state. Geochemists need to come up with new ways to explain oxygen levels on the early Earth."

1.The underlined word "facilitated" in Para. 3 is closest in meaning to＿＿．

A. prevented B. promoted C. interrupted D. witnessed

2.From paragraphs 4 to 6, we can infer that＿＿．

A. phosphorus can keep the productivity of the ocean ecosystem

B. complex animals consume the same amount of oxygen as sponges

C. the sinking of dead organic material into the deep ocean produces oxygen

D. the existence of the first animals marks the beginning of modern food webs

3. From the last paragraph, we can learn Pro. Simon Poulton believes that＿＿．

A. their study gives a new explanation for the high oxygen content in the air

B．oxygen increased greatly in the air as the first animals oxygenated the oceans

C. their study answers the question of how the earth evolved to the present state

D. ocean oxygenation does not necessarily require a rise in atmospheric oxygen

4.The main purpose of the passage is to＿＿．

A. present the view that the first animals played an active role in oxygenating oceans

B. introduce two opposite opinions on how the first animals oxygenated oceans

C．a(chǎn)nalyze how atmospheric oxygen stepped up the evolution of oceanic animals

D. explain how oceanic oxygen determines the amount of atmospheric oxygen

 

Answer 1

1.B

2.A

3.D

4.A

【解析】

試題分析: 本文講述傳統(tǒng)觀點認(rèn)為，地球上氧氣含量的提高引發(fā)了原始動物的進(jìn)化。然而，最新研究表明，早期海洋原始動物的進(jìn)化可能為地球上的海洋提供了最初的氧氣。

1.B 猜測詞意。根據(jù)文中我們認(rèn)為，原始動物的演化在大范圍深層海水氧氣的產(chǎn)生和積累過程中起了至關(guān)重要的作用。原始動物的進(jìn)化或許反過來促進(jìn)了更復(fù)雜、更活躍動物的出現(xiàn)可知選B項。

2.A 推斷題。根據(jù)第五段提到This in turn reduced the productivity of the whole ocean ecosystem, lowering oxygen demand and thus oxygenating the deep ocean. 這種流失反過來降低了整個海洋生態(tài)系統(tǒng)的生物化學(xué)反應(yīng)速率，從而減少了氧氣的需求量，因此同樣有助于深海氧氣含量的增加，故選A項。

3.D 細(xì)節(jié)理解題。根據(jù)最后一段提到This study provides a possible mechanism for ocean oxygenation without the requirement for a rise in atmospheric oxygen. It therefore questions whether the long-standing belief that there was a major rise in atmospheric oxygen at this time is correct. 這項研究為不依賴于大氣氧氣含量上升的海水氧氣化提供了合理解釋。因此，長期以來人們所相信的在那個時候大氣氧氣含量大幅度上升的理論是否正確受到了懷疑，故選D項。

4.A 主旨大意。本文主要在講述傳統(tǒng)觀點認(rèn)為，地球上氧氣含量的提高引發(fā)了原始動物的進(jìn)化。然而，最新研究表明，早期海洋原始動物的進(jìn)化可能為地球上的海洋提供了最初的氧氣，故選A項。

考點:科普類閱讀。