TPO阅读44文本答案翻译.docx

1、TPO阅读44文本答案翻译TPO-44From Fish to Terrestrial VertebratesOne of the most significant evolutionary events that occurred on Earth was thetran siti on of water-dwelli ng fish to terrestrial tetrapods (four-limbed orga ni smswith backbones). Fish probably originated in the oceans, and our first records of

2、 them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, includingfreshwater sett in gs. One of the groups whose fossils are especially commoni n rocksdeposited in fresh water is the lobe-finned f

3、ish.The freshwater Devonian lobe-fi nned fish rhipidistia n crossopterygia n is of particular interest to biologists studying tetrapod evolution. These fish lived in river cha nn els and lakes on large deltas. The delta rocks in which these fossils are found are com mon ly red due to oxidized iron m

4、in erals, in dicati ng that the deltasformed in a climate that had alternate wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians , several such adaptations existed.It is known that

5、 they had lungs as well as gills for breath ing. Cross sect ions cut through some of the fossils reveal that the mud filling the interior of the carcassdiffered in con siste ncy and texture depe nding on its locati on in side the fish. Thesediffere nces suggest a sadlike cavity below the front end o

6、f the gut that can only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for thesefish, but the lungs served as an auxiliary breath ing device for gulp ing air whe n the water became oxyge n depleted, such as duri ng exte nded periods of drought. So, these fish had already

7、evolved one of the prime requisites for living on land: the ability to use air as a source of oxyge n.A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have bee n used as feeb

8、le locomotor devices on land, perhaps good eno ughto allow a fish to flop its way from one pool of water that was almost dry to an adjace nt pond that had eno ugh water and oxyge n for survival. These fins even tually changed into short, stubby legs. The bones of the fins of a Devonian rhipidistian

9、exactly match in number and position the limb bones of the earliest known tetrapods, the amphibia ns. It should be emphasized that the evoluti on of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they helped fish to survive in their existi

10、ng aquatic environment.What ecological pressures might have caused fishes to gradually aba ndon their watery habitat and become increasingly Iand-dwelling creatures? Changes in climateduring the Devonian may have had something to do with this if freshwater areas became progressively more restricted.

11、 Ano ther impetus may have bee n new sources of food.The edges of ponds and streams surely had scattered dead fish and other water-dwelli ng creatures. n additi on, pla nts had emerged in to terrestrialhabitats in areas near streams and ponds, and crabs and other arthropods were alsomembers of this

12、earliest terrestrial com muni ty. BThus, by the Devonian the landhabitat margi nal to freshwater was probably a rich source of protein that could beexploited by an animal that could easily climb out of water. Evidenee from teethsuggests that these earliest tetrapods did not utilize land pla nts as f

13、ood; they were presumably carni vorous and had not developed the ability to feed on pla nts.How did the first tetrapods make the transition to a terrestrial habitat? Like early land pla nts such as rhyni ophytes, they made only a partial tran siti on; they were still quite tied to water. However, ma

14、ny problems that faced early land plants were not applicable to the first tetrapods. The ancestors of these animals alreadyhad a circulatio n system, and they were mobile, so that they could move to water to drink. Furthermore, they already had lungs, which rhipidistians presumably used for auxiliar

15、y breath ing. The prin cipal cha nges for the earliest tetrapods were in the skeletal system changes in the bones of the fins, the vertebral column, pelvicgirdle, and pectoral girdle.P1: One of the most significant evolutionary events that occurred on Earth was thetran siti on of water-dwelli ng fis

16、h to terrestrial tetrapods (four-limbed orga ni smswith backbones). Fish probably originated in the oceans, and our first records of them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, includi

17、ng freshwater sett in gs. One of the groups whose fossils are especially commoni n rocksdeposited in fresh water is the lobe-finned fish.1.Paragraph 1 supports which of the following statements about fish evolution?A.Lobe-finned fish were among the earliest types of fish to appear.B.Fish began livin

18、g in freshwater habitats only after originating elsewhere.C.Lobe-finned fish radiated into almost all available aquatic habitats.D.During the Devonian, I obe-fi nned fish were more com mon in marine tha n in freshwater habitats.P2： The freshwater Devonian lobe-finned fish rhipidistian crossopterygia

19、n is of particular interest to biologists studying tetrapod evolution. These fish lived inriver cha nn els and lakes on large deltas. The delta rocks in which these fossils are found are com mon ly red due to oxidized iron min erals, in dicati ng that the deltasformed in a climate that had alternate

20、 wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians , several such adaptations existed.It is known that they had lungs as well as gills for breath ing. Cross sect ions cut through

21、 some of the fossils reveal that the mud filling the interior of the carcass differed in con siste ncy and texture depe nding on its locati on in side the fish. These differe nces suggest a sadlike cavity below the front end of the gut that can onlybe interpreted as a lung. Gills were undoubtedly th

22、e main source of oxygen for these fish, but the lungs served as an auxiliary breath ing device for gulp ing air whe n the water became oxyge n depleted, such as duri ng exte nded periods of drought. So, these fish had already evolved one of the prime requisites for living on land: the ability to use

23、 air as a source of oxyge n.2.Accord ing to paragraph 2, what do the mi nerals in the delta rocks containing rhipidistian crossopterygian fossils reveal?A.These deltas formed in dry periods but gradually became wetter.B.These deltas contain differe nt types of iron min erals tha n do the surro undin

24、g areas.C.Most rhipidistia n crossopterygia n fish died whe n the climate became dry.D.Rhipidistia n crossopterygia n fish lived in areas that experie need alternate dry and wet periods.3.The word adva ntageous in the passage is closest in meaning toA.ben eficialB.necessaryC.remarkableD.com mon4.In

25、paragraph 2, why does the author in clude the in formati on that mud in siderhipidistian crossopterygian fossils differed in consistency and texture dependingon where the mud was located?A.To provide evidence that rhipidistian crossopterygian lived in river channels and lakes on large deltas.B.To id

26、entify an effect of the oxidation of iron minerals on the evolution of rhipidistia n crossopterygia n.C.To help explain why scientists have concluded that rhipidistian crossopterygian probably had lun gs.D.To expla in why scie ntists decided to cut cross sect ions through some fossils ofrhipidistia

27、n crossopterygia n.5.Which of the sentences below best expresses the esse ntial in formatio n in the highlighted sentence in the passage? In correct choices cha nge the meaning in importa nt ways or leave out esse ntial in formati on.A.Because the lungs of these fish were able to provide only a smal

28、l amount of oxygen, these fish obtained most of their oxygen through their gills during periods ofdrought.B.During periods of exte nded drought, these fish used their lungs to in crease their in take of oxyge n bey ond the levels absorbed by the gills in no rmal times.C.Although these fish primarily

29、 used their gills to obtain oxygen, they used their lungs to obta in oxyge n from the air whe n there was not eno ugh in the water.D.During periods of extended drought, the gills became an auxiliary breathing deviceand the lungs became the main source of oxyge n for these fish.6.Which of the sentenc

30、es below best expresses the esse ntial in formatio n in the highlighted sentence in the passage? In correct choices cha nge the meaning in importa nt ways or leave out esse ntial in formati on.A.Because the lungs of these fish were able to provide only a small amount of oxygen, these fish obtained m

31、ost of their oxygen through their gills during periods ofdrought.B.During periods of exte nded drought, these fish used their lungs to in crease their in take of oxyge n bey ond the levels absorbed by the gills in no rmal times.C.Although these fish primarily used their gills to obtain oxygen, they

32、used their lungs to obta in oxyge n from the air whe n there was not eno ugh in the water.D.During periods of extended drought, the gills became an auxiliary breathing deviceand the lungs became the main source of oxyge n for these fish.P3： A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have bee n used as feeble locomotor devices on land, perhaps good eno ughto allow a fish to flop its way from one pool of wate