1.(Z)Capuchin monkeys often rub their bodies with a certain type of millipede. Laboratory tests show that secretions from the bodies of these millipedes are rich in two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate capuchins. Some scientists hypothesize that the monkeys rub their bodies with the millipedes because doing so helps protect them from mosquitoes.
Which of the following, if true, provides the most support for the scientists’ hypothesis?
A. A single millipede often gets passed around among several capuchins, all of whom rub their bodies with it.
B. The two chemicals that repel mosquitoes also repel several other varieties of insects.
C. The capuchins rarely rub their bodies with the millipedes except during the rainy season, when mosquito populations are at their peak.
D. Although the capuchins eat several species of insects, they do not eat the type of millipede they use to rub their bodies.
E. The two insect-repelling chemicals in the secretions of the millipedes are carcinogenic for humans but do not appear to be carcinogenic for capuchins.
2.(Z)Crowding on Mooreville’s subway frequently leads to delays, because it is difficult for passengers to exit from the trains. Subway ridership is projected to increase by 20 percent over the next 10 years. The Metroville Transit Authority plans to increase the number of daily train trips by only 5 percent over the same period. Officials predict that this increase is sufficient to ensure that the incidence of delays due to crowding does not increase.
Which of the following, if true, provides the strongest grounds for the officials’ prediction?
A. By changing maintenance schedules, the Transit Authority can achieve the 5 percent increase in train trips without purchasing any new subway cars.
B. The Transit Authority also plans a 5 percent increase in the number of bus trips on routes that connect to subways.
C. For most commuters who use the subway system, there is no practical alternative public transportation available.
D. Most of the projected increase in ridership is expected to occur in off-peak hours when trains are now sparsely used.
E. The 5 percent increase in the number of train trips can be achieved without an equal increase in Transit Authority operational costs.
3.(Z)Certain politicians in the country of Birangi argue that a 50 percent tax on new automobiles would halt the rapid increase of automobiles on Birangi’s roads and thereby slow the deterioration of Birangi’s air quality. Although most experts agree that such a tax would result in fewer Birangians buying new vehicles and gradually reduce the number of automobiles on Birangi’s roads, they contend that it would have little impact on Birangi’s air-quality problem.
Which of the following, if true in Birangi, would most strongly support the experts’ contention about the effect of the proposed automobile tax on Birangi’s air-quality problem?
A. Automobile emissions are the largest single source of air pollution.
B. Some of the proceeds from the new tax would go toward expanding the nonpolluting commuter rail system.
C. Currently, the sales tax on new automobiles is considerably lower than 50 percent.
D. Automobiles become less fuel efficient and therefore contribute more to air pollution as they age.
E. The scrapping of automobiles causes insignificant amounts of air pollution.
4.(Z)A mosquito bite can transmit to a person the parasite that causes malaria, and the use of mosquito nets over children’s beds can significantly reduce the incidence of malarial infection for children in areas where malaria is common. Yet public health officials are reluctant to recommend the use of mosquito nets over children’s beds in such areas.
Which of the following, if true, would provide the strongest grounds for the public health officials’ reluctance?
A. Early exposure to malaria increases the body’s resistance to it and results in a lesser likelihood of severe life-threatening episodes of malaria.
B. Mosquito bites can transmit to people diseases other than malaria.
C. Mosquito nets provide protection from some insect pests other than mosquitoes.
D. Although there are vaccines available for many childhood diseases, no vaccine has been developed that is effective against malaria.
E. The pesticides that are most effective against mosquitoes in regions where malaria is common have significant detrimental effects on human health.
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