2016年东南大学考博英语真题

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Between 5, 000 million and 4, 000 million years ago the Earth was formed. By 3, 000 million years ago life had arisen and we have fossils of microscopic bacteria like creatures to prove it. 66 Nobody knows what happened, but theorists agree that the key was the spontaneous arising of self replicating entities, i. e. something equivalent to “genes” in the general sense. The atmosphere of the early Earth probably contained gases still abundant today on other planets in the solar system. Chemists have experimentally reconstructed these ancient conditions in the laboratory. If plausible gases are mixed in a flask with water, and energy is added by an electric discharge (simulated lightning), organic substances are spontaneously synthesized. These include the building blocks of RNA and DNA. It seems probable that something like this happened on the early Earth.

Consequently, the sea would have become a “soup” of prebiological organic compounds. 67 Today the most famous self replicating molecule is DNA (deoxyribonucleic acid) , but it is widely thought that DNA itself could not have been present at the origin of life because its replication is too dependent on support from specialized machinery, which could not have been available before evolution itself began. DNA has been described as a “high-tech” molecule which probably arose some time after the origin of life itself. Perhaps the related molecule RNA, which still plays various vital roles in living cells, was the original self replicating molecule. Or perhaps the primordial replicator was a different kind of molecule altogether. 68 Variants that were particularly good at replication would automatically have come to predominate in the primeval soup. Varieties that did not replicate, or that did so inaccurately, would have become relatively less numerous. This led to ever-increasing efficiency among replicating molecules.

As the competition between replicating molecules warmed up, success must have gone to the ones that happened to hit upon special tricks or devices for their own self preservation and their own rapid replication. The rest of evolution may be regarded as a continuation of the natural selection of replicator molecules, now called genes, by virtue of their capacity to build for themselves efficient devices (cells and multi-cellular bodies) for their own preservation and reproduction. 69 Fossils were not laid down on more than a small scale until the Cambrian era, nearly 600 million years ago. The first vertebrates may date back 530 million years, according to fossil evidence — primitive, lawless fishes with fins, gills, and fishlike muscle patterns — found in China in 1999. Vertebrates appear abundantly in fossil beds between 300 and 400 million years ago. 70 Mammals and, later, birds, arose from two different branches of reptiles. The rapid divergence of mammals into the rich variety of types that we see today, from opossums to elephants, from anteaters to monkeys, seems to have been unleashed into the vacuum left by the catastrophic extinction of the dinosaurs, million years ago.

A. Among vertebrates, the land was first colonized by lobe finned and lung bearing fish about 250 million years ago, then by amphibians and, in more thoroughgoing fashion, by various kinds of animals that we loosely lump together as reptiles.

B. Once self replicating molecules had been formed by chance, something like Darwinian natural selection could have begun: variation would have come into the population because of random errors in copying.

C. It is not enough, of course, that organic molecules appeared in the primeval soup. The crucial step, as noted above, was the origin of self replicating molecules, molecules capable of copying themselves.

D. Although we naturally emphasize the evolution of our own kind — the vertebrates, the mammals, and the primates — these constitute only a small branch of the great tree of life.

E. Three thousand million years is a long time, and it seems to have been long enough to have produced such astonishingly complex contrivances as the vertebrate body and the insect body.

F. Some time between these two dates — independent molecular evidence suggests about 4, 000 million years ago — that mysterious event, the origin of life, must have occurred.

Passage Two

Some rituals of modem domestic living vary little throughout the developed world. One such is the municipal refuse collection, usually once a week, your rubbish bags or the contents of your bin disappear into the bowels of a special lorry and are carted away to the local tip. To economists, this ceremony is peculiar, because in most places it is free. Yes, households pay for the service out of local taxes. 71 Yet the marginal cost of rubbish disposal is not zero at all. The more people throw away, the more rubbish collectors and trucks are needed, and the more the local council has to pay in landfill and tipping fees. 72 But as Don Fullerton and Thomas Kinnaman, two American economists, have found, this seemingly easy application of economic sense to an everyday problem has surprisingly intricate and sometimes disappointing results. In the past few years, several American towns and cities have started charging households for generating rubbish. The commonest system is to sell stickers or tags which householders attach to rubbish bags or cans. Only bags with these labels are picked up in the weekly collection.

In the paper published last year Fullerton and Kinnaman studied the effects of one such scheme, introduced in July 1992 in Charlottesville, Virginia, a town of about 40, 000 people. Residents were charged 80 cents for each sticker. This may sound like the sensible use of market forces. In fact, the authors conclude, the schemes benefits did not cover the cost of printing stickers, the sticker sellers， commissions, and the wages of the people running the scheme. 73 This is inefficient: compacting is done better by machines at landfill sites than by individuals, however enthusiastically. The weight of rubbish collected in Charlottesville fell by a modest 14% . 74 The one bright spot in all this seems to have been a 15% increase in the weight of materials recycled, suggesting that people chose to recycle free rather than pay to have their refuse carted away. But the fee may have little to do with the growth in recycling, as many citizens were already participating in Charlottesville’s voluntary recycling scheme.

75 To discourage dumping, for instance, local councils might have to spend more on catching litters, or raise fines for littering, or cut the price of legitimate rubbish collection.

A. True, the number of bags or cans collected did fall sharply, by 37% between May and September 1992. But rather than buy more tags, people simply crammed more garbage — about 40% more into each container.

B. This looks like the most basic of economic misunderstandings: if rubbish disposal is free, people will produce too much rubbish. The obvious economic solution is to make households pay the marginal cost of disposing of their waste. That will give them an incentive to throw out less and recycle more.

C. City authorities are now considering a project to teach Government waste collectors the skills, such as what rubbish to collect and how to classify it. If approved, the project will help ease the financial burden of the city’s waste treatment.

D. It would be foolish to generalize from this one case, but the moral is clear, economic incentives sometimes produce unforeseen responses.

E. Less pleasing still, some people resorted to illegal dumping rather than pay to have their rubbish removed. This is hard to measure directly. But the authors, observing that a few households in the sample stopped putting rubbish out, guess that illegal dumping may account for 30% 一 40% of the reduction in collected rubbish.

F. But at the margin the price is zero: the family that fills four bins with rubbish each week pays no more than the elderly couple that fills one.

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