1.A new and more aggressive form of the fungus that caused the Irish potato famine of the nineteenthcentury has recently arisen. However, since this new form of the fungus can be killed by increased application of currently used fungicides, it is unlikely that the fungus will cause widespread food shortages in countries that currently rely on potatoes for sustenance.Which of the following, if true, most calls into question the conclusion in the argument above?
(A) Though potatoes are an important staple crop in many parts of the world, people in most countries rely primarily on wheat or rice for sustenance.
(B) Potato farmers in many countries to which the new form of the fungus has spread cannot afford to increase their spending on fungicides.
(C) The new form of the fungus first began to spread when contaminated potato seeds were inadvertently exported from a major potato-exporting country.
(D) Potato farmers in most countries use several insecticides on their crops in addition to fungicides of the sort that kill the new form of the fungus.
(E) Most governments have funds set aside that can be used to alleviate the effects of large-scale disasters such as severe food shortages and floods.
2.As government agencies, faced with budget difficul- ties, reduce their funding for scientific research, a greater amount of such research is being funded by private foundations. This shift means that research projects likely to produce controversial results will almost certainly comprise a smaller proportion of all funded research projects, since private foundations, concerned about their public image, tend to avoid controversy. Which of the following is an assumption on which the argument depends?
(A) Only research that is conducted without concern for the possibility of generating controversy is likely to produce scientifically valid results.
(B) Private foundations that fund scientific research projects usually recognize that controversial results from those projects cannot always be avoided.
(C) Scientists who conduct research projects funded by private foundations are unlikely to allow the concerns of the funding organizations to influ- ence the manner in which they conduct the research.
(D) Many government agencies are more concerned about their public image than are most private foundations.
(E) Government agencies are more willing than are private foundations to fund research projects that are likely to produce controversial results.
3.Juries in criminal trials do not base verdicts on uncor- roborated testimony given by any one witness. Rightly so, because it is usually prudent to be highly skeptical of unsubstantiated claims made by any one person. But then, to be consistent, juries should end an all- too-common practice: convicting defendants on the basis of an uncorroborated full confession. Which of the following, if true, most strengthens the argument above?
(A) Juries often acquit in cases in which a defendant retracts a full confession made before trial.
(B) The process of jury selection is designed to screen out people who have a firm opinion about the defendant's guilt in advance of the trial.
(C) Defendants sometimes make full confessions when they did in fact do what they are accused of doing and have come to believe that the prose- cutor has compelling proof of this.
(D) Highly suggestible people who are accused of wrongdoing sometimes become so unsure of their own recollection of the past that they can come to accept the accusations made against them.
(E) Many people believe that juries should not con- vict defendants who have not made a full con- fession.
4.Although spinach is rich in calcium, it also contains large amounts of oxalic acid, a substance that greatly impedes calcium absorption by the body. Therefore, other calcium-containing foods must be eaten either instead of or in addition to spinach if a person is to be sure of getting enough calcium.
Which of the following, if true, most seriously weakens the argu-ment above?
(A)Rice, which does not contain calcium, counteracts the effects of oxalic acid on calcium absorption.
(B) Dairy products, which contain even more calcium than spinach does, are often eaten by people who eat spinach on a regularbasis.
(C) Neither the calcium nor the oxalic acid in spinach is destroyed when spinach is cooked.
(D) Many leafy green vegetables other than spinach that are rich in calcium also contain high concentrations of oxalic acid.
(E) Oxalic acid has little effect on the body's ability to absorb nutrients other than calcium.
5.Joyce: Three years ago the traffic commission modified our town's busiest intersection for better visibility, a commendable effort to cut down on traffic accidents there. Gary: Over the past three years there have been more, not fewer, traffic accidents per week at that intersection, so the modification has increased the likelihood of accidents there The answer to which of the following questions would be most useful in evaluating Gary's argument?
(A) What proportion of the town's drivers involved in accidents that occurred prior to the modification suffered personal injury in their accidents?
(B) How long, on average, had the members of the traffic commission held their offices when the modification was implemented?
(C) Do a majority of the town's residents approve of the traffic commission's overall performance?
(D) What measures have nearby towns taken within the last three years in order to improve visibil- ity at dangerous intersections?
(E) How has the volume of traffic at the town's busiest intersection changed over the last three years?
6. Women make up the majority of the population in the country, and many of the prescriptions written by doctors for tranquilizers are for women patients. The testing of these drugs for efficacy and the calibration of recommended doses, however, was done only on men. Not even the animals used to test toxicity were female. The statements above, if true, best support which of the following as a conclusion?
(A) Some tranquilizers are more appropriately pre- scribed for women than for men.
(B) There have been no reports of negative side effects from prescribed tranquilizers in women
(C) Tranquilizers are prescribed for patients in some instances when doctors do not feel confident of
(D) The toxicity of drugs to women is less than the toxicity of the same drugs to men.
(E) Whether the recommended dosages of tranquil- izers are optimal for women is not known.
7. Gray wolves have been absent from a large national
park for decades. Park officials wish to reestablish the wolves without jeopardizing any existing species of wildlife there. Since the park contains adequate prey for the wolves and since the wolves avoid close contact with people, reintroducing them would serve the officials' purpose without seriously jeopardizing visitors' safety. Each of the following, if true, strengthens the argument above EXCEPT:
(A) The park is so large that wolves will not need to venture into areas frequented by people.
(B) Rabies is very rare in wolves, and there have been no verified cases of serious human injuries from nonrabid wild wolves since records have been kept.
(C) Ranchers in the region near the park have expressed concern that gray wolves, if reintro- duced, would sometimes prey on their livestock.
(D) Predation by gray wolves on elk in the park is likely to improve the health and viability of the park's elk population as a whole by reducing malnutrition among the elk.
(E) Wolves do not prey on animals of any endangered species that currently inhabit the park.
8. Osteoporosis is a disease that reduces bone mass, lead- ing to fragile bones that break easily. Current treat- ments for osteoporosis such as estrogen or calcitonin help prevent further loss of bone but do not increase bone mass. Since fluoride is known to increase bone mass, administering fluoride to osteoporosis patients would therefore help make their bones less susceptible to breaking. Which of the following, if true, most seriously weakens the argument above?
(A) Most people who suffer from osteoporosis are not aware that administration of fluoride can increase bone mass.
(B) Fluoride is added to drinking water in many locations in order to strengthen the teeth of people who drink the water.
(C) The risk of contracting osteoporosis and other degenerative bone diseases is lessened by exer-
cise and an adequate intake of calcium.
(D) Unlike administration of fluoride, administration of estrogen or calcitonin is known to cause undesirable side effects for many people.
(E) The new bone mass that is added by the admin- istration of fluoride is more brittle and less elastic than normal bone tissue.
9. The closest distance from which an asteroid has been photographed using ground-based radar is 2.2 million miles, the distance from which the asteroid Toutatis was recently photographed. The closest photograph of an asteroid is of Gaspra, which was photographed from a distance of only 10,000 miles. Which of the following can be properly concluded from the statements above?
(A) Toutatis is more likely to collide with the Earththan Gaspra is.
(B) Toutatis, unlike Gaspra, has only recently been discovered.
(C) Asteroids can be photographed only by using ground-based radar.
(D) Ground-based radar photography cannot take photographs of objects much beyond 2.2 million miles from Earth.
(E) The photograph of Gaspra was not taken using ground-based radar.
10. Which of the following most logically completes the argument below? Alone among living species, human beings experience adolescence, a period of accelerated physical growth prior to full maturity.Whether other hominid species, which are now all extinct and are known only through thefossil record, went through adolescence cannot be known, since
(A) the minimum acceleration in physical growth that would indicate adolescence might differ
according to species
(B) the fossil record, though steadily expanding, will always remain incomplete
(C) detecting the adolescent growth spurt requires measurements on the same individual at differ- ent ages
(D) complete skeletons of extinct hominids are extremely rare
(E) human beings might be the first species to bene- fit from the survival advantages, if any, conferred by adolescence
11. Fossils of the coral Acrocora palmata that date from the last period when glaciers grew and consequently spread from the polar regions are found at ocean depths far greater than those at which A. palmata can now survive. Therefore, although the fossilized A. palmata appears indistinguishable from A. palmata now living, it must have differed in important respects to have been able to live in deep water. The argument depends on the assumption that
(A) no fossils of the coral A. palmata have been found that date from periods when glaciers were not spreading from the polar regions
(B) geological disturbances since the last period during which glaciers spread have caused no major downward shift in the location of A. palmata fossils
(C) A. palmata now live in shallow waters in most of the same geographical regions as those in which deep-lying A. palmata fossils have been found
(D) A. palmata fossils have been found that date from each of the periods during which glaciers are known to have spread from the polar region
(E) A. palmata can live at greater depths where the ocean temperature is colder than they can where the ocean temperature is warmer
12.Conservationists have believed that by concentrating their preservation efforts on habitats rich in an easily surveyed group of species, such as birds, they would thereby be preserving areas rich in overall species diversity. This belief rests on a view that a geographical area rich in one group of species will also be rich in the other groups characteristic of the entire regional climate zone.
Which of the following findings about widely scattered tracts 10 kilometers by 10 kilometers in a temperate climate zone would most seriously challenge the conservationists' assumptions?
(A) The tracts show little damage from human intrusion and from pollution by human activities.
(B) Where a certain group of species, such as birds, is abundant, there is also an abundance of the species, such as insects, on which that group of species feeds, or in the case of plants, of the land and water resources it requires.
(C) The area of one of the tracts is generally large enough to contain a representative sample of the organisms in the region.
(D) There is little overlap between the list of tracts that are rich in species of butterflies and the list of those that are rich in species of birds.
(E) The highest concentration of individuals of rare species is found where the general diversity of species is greatest.