Test Prep MCAT Test Exam (page: 7)
Test Prep Medical College Admission Test: Verbal Reasoning, Biological Sciences, Physical Sciences, Writing Sample
Updated on: 15-Dec-2025

The Russian wheat aphid, Diuraphis noxia, is a small green insect discovered in southern Russia around the turn of the century. Agricultural researchers are not quite sure, but they believe the Russian aphid adapted itself to wheat about ten thousand years ago, when the crop was first domesticated by man. What is not in doubt is the insect's destructiveness. Spread by both wind and human transport, the Russian aphid has destroyed wheat fields throughout Asia, Africa, and Latin America. Until a few years ago, the United States had been free of this pest. But in the spring of 1986, a swarm of Russian aphids crossed the Mexican border and settled a few hundred miles north, in central Texas. From there, it quickly spread to other Western states, destroying wheat fields all along its path. In fact, the level of destruction has been so great over the past five years that entomologists are calling the Russian aphid the greatest threat to American agriculture since the Hessian fly, Phytophaga destructor, was inadvertently brought to the colonies on ships by German mercenary troops during the Revolutionary War. A combination of several factors has made it particularly difficult to deal with the threat posed by this aphid. First, Russian aphids reproduce asexually at a phenomenal rate. This process, known as parthenogenesis, often results in as many as twenty generations of insects in a single year. Although most generations remain in a limited geographic area because they have no wings, a few generations are born with wings, allowing the insect to spread to new areas. Second, because wheat is a crop with a very low profit margin, most American farmers do not spray it with pesticides; it simply is not economical to do so. And since the Russian aphid has only recently entered the United States, it has no natural enemies among North American insects or animals. As a result, there have been no man-made or natural obstacles to the spread of the Russian aphid in the United States.
Agricultural researchers seeking to control the Russian aphid have looked to its place of origin for answers. In the Soviet Union, the Russian aphid has been kept in check by predators which have evolved alongside it over many thousands of years. One species of wasp seems to be particularly efficient at destroying the aphid. The pregnant females of the species search the Russian aphid's home, the interior of a wheat stalk, sting the aphid into paralysis, and then inject an egg into its body. When the egg hatches the wasp larva feeds off of the aphid, killing it in the process.
The introduction of predators like the wasp, coupled with the breeding of new strains of insect-resistant wheat, may substantially curb the destructiveness of the Russian aphid in the future. For the time being, however, American farmers are left to their own devices when it comes to protecting their wheat crops.
The author suggests the best way to control the Russian aphid population in the United States is to:

The Russian wheat aphid, Diuraphis noxia, is a small green insect discovered in southern Russia around the turn of the century. Agricultural researchers are not quite sure, but they believe the Russian aphid adapted itself to wheat about ten thousand years ago, when the crop was first domesticated by man. What is not in doubt is the insect's destructiveness. Spread by both wind and human transport, the Russian aphid has destroyed wheat fields throughout Asia, Africa, and Latin America. Until a few years ago, the United States had been free of this pest. But in the spring of 1986, a swarm of Russian aphids crossed the Mexican border and settled a few hundred miles north, in central Texas. From there, it quickly spread to other Western states, destroying wheat fields all along its path. In fact, the level of destruction has been so great over the past five years that entomologists are calling the Russian aphid the greatest threat to American agriculture since the Hessian fly, Phytophaga destructor, was inadvertently brought to the colonies on ships by German mercenary troops during the Revolutionary War. A combination of several factors has made it particularly difficult to deal with the threat posed by this aphid. First, Russian aphids reproduce asexually at a phenomenal rate. This process, known as parthenogenesis, often results in as many as twenty generations of insects in a single year. Although most generations remain in a limited geographic area because they have no wings, a few generations are born with wings, allowing the insect to spread to new areas. Second, because wheat is a crop with a very low profit margin, most American farmers do not spray it with pesticides; it simply is not economical to do so. And since the Russian aphid has only recently entered the United States, it has no natural enemies among North American insects or animals. As a result, there have been no man-made or natural obstacles to the spread of the Russian aphid in the United States.
Agricultural researchers seeking to control the Russian aphid have looked to its place of origin for answers. In the Soviet Union, the Russian aphid has been kept in check by predators which have evolved alongside it over many thousands of years. One species of wasp seems to be particularly efficient at destroying the aphid. The pregnant females of the species search the Russian aphid's home, the interior of a wheat stalk, sting the aphid into paralysis, and then inject an egg into its body. When the egg hatches the wasp larva feeds off of the aphid, killing it in the process.
The introduction of predators like the wasp, coupled with the breeding of new strains of insect-resistant wheat, may substantially curb the destructiveness of the Russian aphid in the future. For the time being, however, American farmers are left to their own devices when it comes to protecting their wheat crops.
According to the passage, the Russian wheat aphid and the Hessian fly are comparable with respect to:
I) the amount of destruction they have caused.
II). the means by which they reproduce.
III). the ways in which they entered the United States.

The Russian wheat aphid, Diuraphis noxia, is a small green insect discovered in southern Russia around the turn of the century. Agricultural researchers are not quite sure, but they believe the Russian aphid adapted itself to wheat about ten thousand years ago, when the crop was first domesticated by man. What is not in doubt is the insect's destructiveness. Spread by both wind and human transport, the Russian aphid has destroyed wheat fields throughout Asia, Africa, and Latin America. Until a few years ago, the United States had been free of this pest. But in the spring of 1986, a swarm of Russian aphids crossed the Mexican border and settled a few hundred miles north, in central Texas. From there, it quickly spread to other Western states, destroying wheat fields all along its path. In fact, the level of destruction has been so great over the past five years that entomologists are calling the Russian aphid the greatest threat to American agriculture since the Hessian fly, Phytophaga destructor, was inadvertently brought to the colonies on ships by German mercenary troops during the Revolutionary War. A combination of several factors has made it particularly difficult to deal with the threat posed by this aphid. First, Russian aphids reproduce asexually at a phenomenal rate. This process, known as parthenogenesis, often results in as many as twenty generations of insects in a single year. Although most generations remain in a limited geographic area because they have no wings, a few generations are born with wings, allowing the insect to spread to new areas. Second, because wheat is a crop with a very low profit margin, most American farmers do not spray it with pesticides; it simply is not economical to do so. And since the Russian aphid has only recently entered the United States, it has no natural enemies among North American insects or animals. As a result, there have been no man-made or natural obstacles to the spread of the Russian aphid in the United States.
Agricultural researchers seeking to control the Russian aphid have looked to its place of origin for answers. In the Soviet Union, the Russian aphid has been kept in check by predators which have evolved alongside it over many thousands of years. One species of wasp seems to be particularly efficient at destroying the aphid. The pregnant females of the species search the Russian aphid's home, the interior of a wheat stalk, sting the aphid into paralysis, and then inject an egg into its body. When the egg hatches the wasp larva feeds off of the aphid, killing it in the process.
The introduction of predators like the wasp, coupled with the breeding of new strains of insect-resistant wheat, may substantially curb the destructiveness of the Russian aphid in the future. For the time being, however, American farmers are left to their own devices when it comes to protecting their wheat crops.
The author most likely believes American farmers will:

Millenialism is, generally speaking, the religious belief that salvation and material benefits will be conferred upon a society in the near future as the result of some apocalyptic event. The term derives from the Latin word for 1,000; in early Christian theology, believers held that Christ would return and establish his kingdom on earth for a period of a thousand years.
Millenialist movements, Christian and non-Christian, have arisen at various points throughout history, usually in times of great crisis or social upheaval. In "nativistic" millenialist movements, a people threatened with cultural disintegration attempts to earn its salvation by rejecting foreign customs and values and returning to the "old ways." One such movement involving the Ghost Dance cults, named after the ceremonial dance which cult members performed in hope of salvation, flourished in the late 19th century among Indians of the western United States.
By the middle of the 19th century, western expansion and settlement by whites was seriously threatening Native American cultures. Mining, agriculture and ranching encroached on and destroyed many Indian land and food sources. Indian resistance led to a series of wars and massacres, culminating in the U.S. Government's policy of resettlement of Indians onto reservations which constituted a fraction of their former territorial base. Under these dire circumstances, a series of millenialist movements began among western tribes.
The first Ghost Dance cult arose in western Nevada around 1870. A Native American prophet named Wodziwob, a member of a Northern Paiute tribe, received the revelation of an imminent apocalypse which would destroy the white man, restore all dead Indians to life, and return to the Indians their lands, food supplies (such as the vanishing buffalo), and old way of life. The apocalypse was to be brought about with the help of a ceremonial dance and songs, and by strict adherence to a moral code which, oddly enough, strongly resembled Christian teaching. In the early 1870s, Wodziwob's Ghost Dance cult spread to several tribes in California and Oregon, but soon died out or was absorbed into other cults.
A second Ghost Dance cult, founded in January 1889, evolved as the result of a similar revelation. This time Wovoka ­ another Northern Paiute Indian, whose father had been a disciple of Wodziwob ­ received a vision during a solar eclipse in which he died, spoke to God, and was assigned the task of teaching the dance and the millennial message. With white civilization having pushed western tribes ever closer to the brink of cultural disintegration during the previous twenty years, the Ghost Dance movement spread rapidly this time, catching on among tribes from the Canadian border to Texas, and from the Missouri River to the Sierra Nevadas ­ an area approximately one-third the size of the continental United States.
Wovoka's Ghost Dance doctrine forbade Indian violence against whites or other Indians; it also involved the wearing of "ghost shirts," which supposedly rendered the wearers invulnerable to the white man's bullets. In 1890, when the Ghost Dance spread to the Sioux Indians, both the ghost shirts and the movement itself were put to the test. Violent resistance to white domination had all but ended among the Sioux by the late 1880s, when government- ordered reductions in the size of their reservations infuriated the Sioux, and made them particularly responsive to the millenialist message of the Ghost Dance. As the Sioux organized themselves in the cult of the dance, an alarmed federal government resorted to armed intervention which ultimately led to the massacre of some 200 Sioux men, women and children at Wounded Knee, South Dakota in December of 1890. The ghost shirts had been worn to no avail, and Wounded Knee marked the end of the second Ghost Dance cult.
The passage implies that the second Ghost Dance cult gained widespread popularity quickly because:

Millenialism is, generally speaking, the religious belief that salvation and material benefits will be conferred upon a society in the near future as the result of some apocalyptic event. The term derives from the Latin word for 1,000; in early Christian theology, believers held that Christ would return and establish his kingdom on earth for a period of a thousand years.
Millenialist movements, Christian and non-Christian, have arisen at various points throughout history, usually in times of great crisis or social upheaval. In "nativistic" millenialist movements, a people threatened with cultural disintegration attempts to earn its salvation by rejecting foreign customs and values and returning to the "old ways". One such movement involving the Ghost Dance cults, named after the ceremonial dance which cult members performed in hope of salvation, flourished in the late 19th century among Indians of the western United States.
By the middle of the 19th century, western expansion and settlement by whites was seriously threatening Native American cultures. Mining, agriculture and ranching encroached on and destroyed many Indian land and food sources. Indian resistance led to a series of wars and massacres, culminating in the U.S. Government's policy of resettlement of Indians onto reservations which constituted a fraction of their former territorial base. Under these dire circumstances, a series of millenialist movements began among western tribes.
The first Ghost Dance cult arose in western Nevada around 1870. A Native American prophet named Wodziwob, a member of a Northern Paiute tribe, received the revelation of an imminent apocalypse which would destroy the white man, restore all dead Indians to life, and return to the Indians their lands, food supplies (such as the vanishing buffalo), and old way of life. The apocalypse was to be brought about with the help of a ceremonial dance and songs, and by strict adherence to a moral code which, oddly enough, strongly resembled Christian teaching. In the early 1870s, Wodziwob's Ghost Dance cult spread to several tribes in California and Oregon, but soon died out or was absorbed into other cults.
A second Ghost Dance cult, founded in January 1889, evolved as the result of a similar revelation. This time Wovoka ­ another Northern Paiute Indian, whose father had been a disciple of Wodziwob ­ received a vision during a solar eclipse in which he died, spoke to God, and was assigned the task of teaching the dance and the millennial message. With white civilization having pushed western tribes ever closer to the brink of cultural disintegration during the previous twenty years, the Ghost Dance movement spread rapidly this time, catching on among tribes from the Canadian border to Texas, and from the Missouri River to the Sierra Nevadas ­ an area approximately one-third the size of the continental United States.
Wovoka's Ghost Dance doctrine forbade Indian violence against whites or other Indians; it also involved the wearing of "ghost shirts," which supposedly rendered the wearers invulnerable to the white man's bullets. In 1890, when the Ghost Dance spread to the Sioux Indians, both the ghost shirts and the movement itself were put to the test. Violent resistance to white domination had all but ended among the Sioux by the late 1880s, when government- ordered reductions in the size of their reservations infuriated the Sioux, and made them particularly responsive to the millenialist message of the Ghost Dance. As the Sioux organized themselves in the cult of the dance, an alarmed federal government resorted to armed intervention which ultimately led to the massacre of some 200 Sioux men, women and children at Wounded Knee, South Dakota in December of 1890. The ghost shirts had been worn to no avail, and Wounded Knee marked the end of the second Ghost Dance cult.
The passage implies that a paradoxical element of the Ghost Dance cults was their: