沒有陽光就不能進行光合作用，地面生物就無法生存了。但是在2000—3000米深的海底，沒有陽光的地方，各種生物又是以什么為食物來維持生命呢？
對應(yīng)考題：2009年1月15日北美托福考試聽力第7篇
Once it seemed that the ocean floor was a desert of darkness. As everyone knew, sunlight was what made life possible by fueling photosynthesis, and sunlight can penetrate only the first few hundred yards of the ocean’s great depths. Lower, a few creatures might still eke out a living by scrounging the organic detritus that drifts down from the surface of the sea. But thousands of feet down, in the utter blackness at the ocean’s bottom, there could be practically nothing.
Then, in 1977, underwater explorers discovered that there was in fact something, and quite a lot of it. At mid-ocean ridges, where new ocean floor rises up as molten rock from Earth’s interior, where cold seawater mixes with the rising magma and, heated to 650 degrees, spews back up through chimney-shaped hydrothermal vents, researchers stumbled across bustling ecosystems. Clinging to the sides of the chimneys were thick white mats of bacteria; around them were eight-foot-long stalk-shaped worms, rocking in the water, while eyeless shrimp seethed around the chimneys like maggots. All were thriving on the energy bound up in the vents’ sulfur compounds. The seafloor might still be dark, but now it was known to be dotted with gardens.
In just the past eight years, however, underwater explorers have discovered that this picture is still incomplete: there is light at the bottom of the sea. Hydrothermal vents glow, and while the light is too faint to be perceived by the human eye, that hardly means it is without significance. Physicists maintain that although some of the light may be created by the intense heat, much of it must be attributed to some as-yet- unknown process. Biologists, meanwhile, say there is sufficient light at these vents for photosynthesis to take place. Researchers can’t say yet whether any creatures are actually living off this light, but if they are, they will represent the first known instance of natural photosynthesis without sunlight. The evolutionary implications may run deeper: it’s possible not only that this deep light is fueling photosynthesis now, but that, 3.8 billion years ago, it got the whole process started.
本篇關(guān)鍵詞：
Photosynthesis
thousands of feet down
ocean’s bottom
mid-ocean ridges
650 degrees
bustling ecosystems
bound up in
sulfur compounds
light at the bottom of the sea
photosynthesis without sunlight
中文相關(guān)知識：
無處不在的細菌：沒有陽光就不能進行光合作用，地面生物就無法生存了。但是在2000—3000米深的海底，沒有陽光的地方，各種生物又是以什么為食物來維持生命呢？科學(xué)家從海底采取的水樣中發(fā)現(xiàn)了奧妙。原來在水下2500到3000米的海底常有溫泉出現(xiàn)，這些溫泉噴涌出高達350攝氏度的水流。海底熱泉水從地下帶上來許多硫酸鹽，硫酸鹽在高溫高壓下變成了有臭雞蛋味的硫化氫，一些以硫化氫為營養(yǎng)的細菌以極快的速度繁衍。細菌通過攝取溫泉里豐富的化合物獲得能量，它們幫助溫泉水把周圍變成一片生機勃勃的海底綠洲。小動物就以細菌為食，大動物又以小動物為食，這樣就形成了新的食物鏈。
對應(yīng)考題：2009年1月15日北美托福考試聽力第7篇
Once it seemed that the ocean floor was a desert of darkness. As everyone knew, sunlight was what made life possible by fueling photosynthesis, and sunlight can penetrate only the first few hundred yards of the ocean’s great depths. Lower, a few creatures might still eke out a living by scrounging the organic detritus that drifts down from the surface of the sea. But thousands of feet down, in the utter blackness at the ocean’s bottom, there could be practically nothing.
Then, in 1977, underwater explorers discovered that there was in fact something, and quite a lot of it. At mid-ocean ridges, where new ocean floor rises up as molten rock from Earth’s interior, where cold seawater mixes with the rising magma and, heated to 650 degrees, spews back up through chimney-shaped hydrothermal vents, researchers stumbled across bustling ecosystems. Clinging to the sides of the chimneys were thick white mats of bacteria; around them were eight-foot-long stalk-shaped worms, rocking in the water, while eyeless shrimp seethed around the chimneys like maggots. All were thriving on the energy bound up in the vents’ sulfur compounds. The seafloor might still be dark, but now it was known to be dotted with gardens.
In just the past eight years, however, underwater explorers have discovered that this picture is still incomplete: there is light at the bottom of the sea. Hydrothermal vents glow, and while the light is too faint to be perceived by the human eye, that hardly means it is without significance. Physicists maintain that although some of the light may be created by the intense heat, much of it must be attributed to some as-yet- unknown process. Biologists, meanwhile, say there is sufficient light at these vents for photosynthesis to take place. Researchers can’t say yet whether any creatures are actually living off this light, but if they are, they will represent the first known instance of natural photosynthesis without sunlight. The evolutionary implications may run deeper: it’s possible not only that this deep light is fueling photosynthesis now, but that, 3.8 billion years ago, it got the whole process started.
本篇關(guān)鍵詞：
Photosynthesis
thousands of feet down
ocean’s bottom
mid-ocean ridges
650 degrees
bustling ecosystems
bound up in
sulfur compounds
light at the bottom of the sea
photosynthesis without sunlight
中文相關(guān)知識：
無處不在的細菌：沒有陽光就不能進行光合作用，地面生物就無法生存了。但是在2000—3000米深的海底，沒有陽光的地方，各種生物又是以什么為食物來維持生命呢？科學(xué)家從海底采取的水樣中發(fā)現(xiàn)了奧妙。原來在水下2500到3000米的海底常有溫泉出現(xiàn)，這些溫泉噴涌出高達350攝氏度的水流。海底熱泉水從地下帶上來許多硫酸鹽，硫酸鹽在高溫高壓下變成了有臭雞蛋味的硫化氫，一些以硫化氫為營養(yǎng)的細菌以極快的速度繁衍。細菌通過攝取溫泉里豐富的化合物獲得能量，它們幫助溫泉水把周圍變成一片生機勃勃的海底綠洲。小動物就以細菌為食，大動物又以小動物為食，這樣就形成了新的食物鏈。