GRE Exam Dumps : GRE General Test

In 1995 the United States National Park Service reintroduced wolves into Yellowstone National Park, from which they had been eliminated decades before by overhunting. Biologists hoped the reintroduction would return the park's mix of animals to a more natural state. After the wolves disappearance, the population of their onetime prey, the elk. had burgeoned. Subsequently, new tree growth declined as multiplying elk browsed young trees, denuding certain areas of the park. Following the wolves" return, the elk population declined and young trees rebounded. Most scientists attribute the vegetation changes to the wolves1 return. However. Ration observes that Yellowstone has not had a harsh winter since wolf numbers reached high levels and suggests that elk may not have needed to resort to trees for food.

It can be inferred from the passage that the scientists would he most likely to cite which of the following in support of their view?

The sales tax on clothing items in Country A is 25 percent of the purchase price of the item, and the sales tax on clothing items in Country B is 20 percent of the purchase price of the item. If the two countries have the same currency and if the price of a certain clothing item is the same in both countries, what percent greater is the amount of sales tax on the clothing item purchased in Country A than the amount of sales tax on the clothing item purchased in Country B ?

Instances of "galactic cannibalism"—mergers in which large galaxies completely consume smaller ones—may be fairly common. Tidal forces produced by the Milky Way's powerful gravity, for example, appear to be dismantling and engulfing a dwarf galaxy in the constellation Sagittarius, producing large clumps and streamers of stars connecting the two galaxies. Astronomers have also observed two dense clusters of stars and gas at the heart of the Andromeda galaxy, an apparent "double nucleus" that may contain the remnant of a cannibalized dwarf galaxy. But this twin-lobed appearance could also be created by two parts of a single nucleus bisected by a lane of dust. Scientists believe that only about 25 percent of such apparent double nuclei actually represent galactic cannibalism. Many of the rest result from the illusion of proximity that occurs when objects at different distances appear along the same line of sight: others consist of debris from galactic "collisions." in which one galaxy has passed through another without merging, causing waves of new star formation.

The primary purpose of the passage is to