15.15

Most large corporations in the United States were
once run by individual capitalists who owned enough
stock to dominate the board of directors and dictate
company policy. Because putting such large amounts of
(5) stock on the market would only depress its value, they
could not sell out for a quick profit and instead had to
concentrate on improving the long-term productivity of
their companies. Today, with few exceptions, the stock
of large United States corporations is held by large
(10) institutions-pension funds, for example-and because
these institutions are prohibited by antitrust laws from
owning a majority of a company's stock and from
actively influencing a company's decision-making, they
can enhance their wealth only by buying and selling
(15) stock in anticipation of fluctuations in its value. A
minority shareholder is necessarily a short term trader.
As a result, United States productivity is unlikely to
improve unless shareholders and the managers of the
companies in which they invest are encouraged to
(20) enhance long-term productivity (and hence long-term
profitability), rather than simply to maximize shortterm
profits.
Since the return of the old-style capitalist is unlikely,
today's short-term traders must be remade into
(25) tomorrow's long-term capitalistic investors. The legal
limits that now prevent financial institutions from
acquiring a dominant shareholding position in a corporation
should be removed, and such institutions encouraged
to take a more active role in the operations of the
(30) companies in which they invest. In addition, any institution
that holds twenty percent or more of a company's
stock should be forced to give the public one day's
notice of the intent to sell those shares. Unless the
announced sale could be explained to the public on
(35) grounds other than anticipated future losses, the value of
the stock would plummet and, like the old-time capitalists,
major investors could cut their losses only by
helping to restore their companies' productivity. Such
measures would force financial institutions to become
(40) capitalists whose success depends not on trading shares
at the propitious moment, but on increasing the productivity
of the companies in which they invest.
88. In the passage, the author is primarily concerned with doing which of the following?
(A) Comparing two different approaches to a problem
(B) Describing a problem and proposing a solution
(C) Defending an established method
(D) Presenting data and drawing conclusions from the data
(E) Comparing two different analyses of a current situation
89. It can be inferred from the passage that which of the following is true of majority shareholders in a corporation?
(A) They make the corporation's operational management decisions.
(B) They are not allowed to own more than fifty percent of the corporation's stock.
(C) They cannot make quick profits by selling their stock in the corporation.
(D) They are more interested in profits than in productivity.
(E) They cannot sell any of their stock in the corporation without giving the public advance notic.

RC 15.14

A meteor stream is composed of dust particles that have been ejected from a parent comet at a variety of
velocities. These particles follow the same orbit as the parent comet, but due to their differeing velocities they
slowly gain on or fall behind the disintegrating comet until a shroud of dust surrounds the entire cometary orbit.
Astronomers have hypothesized that a meteor stream should broaden with time as the dust particles' individual
orbits are perturbed by planetary gravitational fields. A recent computer-modeling experimetn tested this
hypothesis by tracking the influence of planetary gravitation over a projected 5,000-year period on the positions
of a group of hypothetical dust particles. In the model, the particles were randomly distributed throughout a
computer simulation of the orbit of an actual meteor stream, the Geminid. The researcher found, as expected,
that the computer-model stream broadened with time. Coventional theories, however, predicted that the
distribution of particles would be increaingly dense toward the center of a meteor stream. Surpringly, the
computer-model meteor stream gradually came to resemble a thick-walled, hollow pipe.
Whenever the Earth passes through a meteor stream, a meteor shower occurs. Moving at a li little over 1,500,000
miles per day around its orbit, the Earth would take, on average, just over a day to cross the hollow,
computer-model Geminid stream if the stream were 5,000 years old. Two brief periods of peak meteor activity
during the shower would be observed, one as the Earth entered the thick-walled "pipe" and one as it exited.
There is no reason why the Earth should always pass through the stream's exact center, so the time interval
between the two bursts of activity would vary from one year to the next.
Has the predicted twin-peaked activity been observed for the actual yearly GEminid meteor shower? The
Geminid data between 1970 and 1979 show just such a bifurcation, a secondary burst of meteor activity being clearly visible at an average of 19 hourse (1,200,000 miles) after the first burst. The time intervals between the
bursts suggest the actual Geminid stream is about 3,000 years old.

80. The primary focus of the passage is on which of the following?
(A) Comparing two scientific theories and contrasting the predictions that each would make concerning a natural
phenomenon
(B) Describing a new theoretical model and noting that it explains the nature of observations made of a particular
natural phenomenon
(C) Evaluating the results of a particular scientific experiment and suggesting further areas for research
(D) Explaining how two different natural phenomena are related and demonstrating a way to measure them
(E) Analyzing recent data derived from observations of an actual phenomenon and constructing a model to
explain the data
81. According to the passage, which of the following is an accurate statement concerning meteor streams?
(A) Meteor streams and comets start out with smiliar orbits, but only those of meteor streams are perturbed by
planetary gravittion.
(B) Meteor streams grow as dust particles are attracted by the gravitational fields of comets.
(C) Meteor streams are composed of dust particles derived from comets.
(D) Comets may be composed of several kinds of materials, while meteor streams consitst only of large dust
particles.
(E) Once formed, meteor streams hasten the further disintegration of comets
.
82. The author states that the research described in the first paragraph was undertaken in order to
(A) determine the age of an actual meteor stream
(B) Identify the various structural features of meteor streams
(C) explore the nature of a particularly interesting meteor stream
(D) test the hypothesis that meteor streams become broader as they age
(E) show that a computer model could help in explaining actual astronomical data

83. It can be inferred from the passage that which of the following would most probably be observed during the
Earth's passage through a meteor stream if the conventional theories mentioned in line 18 were
(A) Meteor activity would gradually increase to a single, intense peak, and then gradually decline.
(B) Meteor activity would be steady throughout the period of the meteor shower.
(C) Meteor activity would rise to a peak at the beginning and at the end of the meteor shower.
(D) Random bursts of very high meteor activity would be interspersed with periods of very little activity.
(E) In years in which the Earth passed through only the outer areas of a meteor stream, meteor activity would be
absent.


84. According to the passage, why do the dust particles in a meteor stream eventually surround a comet's
orginla orbit?
(A) They are ejected by the comet at differing velocities.
(B) Their orbits are uncontrolled by planetary gravitational fields.
(C) They become part of the meteor stream at different times.
(D) Their velocity slows over time.
(E) Their ejection velocity is slower than that of the comet.

85. The passage suggests that which of the following is a prediction concerning meteor streams that can be
derived from both the conventional theories mentioned in line 18 and the new computer-derived theory(A) Dust particles in a meteor stream will usually be distributed evenly throughout any cross section of the
steam.
(B) The orbits of most meteor streams should cross the orbit of the Earth at some point and give rise to a meteor
shower.
(C) Over time the distribution of dust in a meteor stream will usually become denser at the outside edges of the
stream than at the center.
(D) Meteor showers caused by older by older meteor streams should be, on average, longer in duration than
those caused by very young meteor streams.
(E) The individual dust particles in older meteor streams should be, on average, smaller than those that
compose younger meteor streams.

86. It can be inferred from the last paragraph of the passage that which of the following must be true of the Earth
as it orbits the Sun?
(A) Most meteor streams it encounters are more than 2,000 years old.
(B) When passing through a meteor stream, it usually passes near to the stream's center.
(C) It crosses the Geminid meteor stream once every year.
(D) It usually takes over a day to cross the actual Geminid meteor stream.
(E) It accounts of msot of the gravitaitonal perturbation affecting the Geminid meteor stream.


87. Which of the following is an assumption underlying the last sentence of the passage?
(A) In each of the years between 1970 and 1979, the Earth took exactly 19 hours to cross the Geminid meteor
stream.
(B) The comet associated with the Geminid meteor stream has totally disintegrated.
(C) The Geminid meteor stream should continue to exist for at least 5,000 years.
(D) The Geminid meteor stream has not broadended as rapidly as the conventiona ltheories would have
predicted.
(E) The computer-model Geminid meteor stream provides an accurate representation of the development of the
actual Geminid stream.

RC 15.13

Two recent publications offer different assessment of the career of the famous British nurse Florence
Nightingale. A book by Anne Summers seeks to debunk the idealizations and present a reality at odds with
Nightingale's heroic reputation. According to Summers, Nightingale's importance during the Crimean War
has been exaggerated: not until near the war's end did she become supervisor of the female nurses.
Additionally, Summers writes that the contribution of the nurses to the relief of the wounded was at best
marginal. The prevailing problems of military medicine were caused by army organizaitonal pratices, and
the addition of a few nurses to the medical staff could be no more than symbolic. Nightingale's place in the
national pantheon, Summers asserts, is lrgely due to the propagandistic efforts of contemporary newspaper
reporters.
By contrast, the editors of a new volume of Nightingale's letters view Nightingale as a person who
significantly influenced not only her own age but also subsequenct generations. They highlight her ongoing
efforts to reform sanitary conditions after the war. For example, when she leanred that peacetime living
conditions in British barracks were so horrible that the death rate of enlisted men far exeeded that ofneighboring civilian populations, she succeeded in persuading the government to establish a Royal
Commission on the Health of the Army. She used sums raised through public contributions to found a
nurses' traning hospital in London. Even in administrative matters, the editors assert, her practical
intelligence was formidable: as recently as 1947 the British Army's medical services were still using the
cost-accounting system she had devised in the 1860's.
I believe that the evidence of her letters supports continued respect for Nightingale's brilliance and creativity.
When counseling a village schoolmaster to encourage children to use their faculties of observation, she
sounds like a modern educator. Her insistence on classifying the problems of the needy in order to devise
appropriate treatments is similar to the approach of modern social workers. In sum, although Nightingale
may not have achieved all of her goals during the Crimean War, her breadth of vision and ability to realize
ambitious projects have earned her an eminent place among the ranks of social pioneers.

73. The passage is primarily concerned with evaluating
(A) the importance of Florence Nightingale's innovations in the field of nursing
(B) contrasting approaches to the writing of historical biography
(C) contradictory accounts of Florence Nightingale's historical significance
(D) the quality of health care in nineteenth-century England
(E) the effect of the Crimean War on developments in the field of health care

74. According to the passage, the editors of Nightingale's letters credit her with contributing to which of the
following?
(A) Improving of the survival rate for soldiers in British Army hospitals during the Crimean War
(B) The development of a nurses' training curriculum that was far in advance of its day
(C) The increase in the number of women doctors practicing in British Army hospitals
(D) Establishment of the first facility for traiing nurses at a major British university
(E) The creation of an organization for monitoring the peacetime living conditions of British soldiers

75. The passage suggests which of the following about Nightingale's relationship with the British public of her
day?
(A) She was highly respected, her projects receiving popular and governmental support.
(B) She encountered resistance both from the army establishment and the general public.
(C) She was supported by the working classes and opposed by the wealthier classes.
(D) She was supported by the military establishment but had to fight the governmental bureaucracy.
(E) After intially being received with enthusiams, she was quickly forgotten.

76. The passage suggests which of the following about sanitary conditions in Britain after the Crimean War?
(A) While not ideal, they were superior to those in other parts of the world.
(B) Compared with conditions before the war, they had deteriorated.
(C) They were more advanced in rural areas than in the urban centers.
(D) They were worse in military camps than in the neighboring civilian populations.
(E) They were unifromaly crude and unsatisfactory throughout England.

77. Which which of the following statements regarding the differing interpretations of Nightingale's importance would the author most likely agree?
(A) Summers misunderstood both the importance of Nightingale's achievements during the Crimean War and
her subsequent influence on British policy.
(B) The editors of Nightingale's letters made some valid points about her practical achievements, but they still
exaggerated her influence on subsequent generations.
(C) Although Summers' account of Nightingale's role in the Crimean War may be accurate, she ignored
evidence of Nightingales' subsequent achievement that suggests that her reputation as an eminent social
reformer is welldeserved.
(D) The editors of Nightingale's letters mistakenly propagated the outdated idealization of Nightingale that only
impedes attempts to arrive at a balance assessment of her true role.
(E) The evidence of Nightingale's letters supports Summers' conclusions both about Nightingale's activities and
about her influence

78. Which of the following is an assumption underlying the author's assessment of Nightingale's creativity?
(A) Educational philosophy in Nightingale's day did not normally emphasize developing children's ability to
observe.
(B) Nightingale was the first to notice the poor living conditions in British military barracks in peacetime.
(C) No educator before Nightingale had thought to enlist the help of village shcoolmasters in introducing new
teaching techniques.
(D) Until Nightingale began her work, there was no concept of organized help for the needy in
nineteenth-century Britain.
(E) The British Army's medical services had no cost-accounting system until Nightingale devised one in the
1860's.

79. In the last paragraph, the author is primarily concerned with
(A) summarizing the arguments about Nightingale presented in the first two paragraphs
(B) refuting the view of Nightingale's career presented in the preceding pargraph
(C) analyzing the weaknesses of the evidence presented elsewhere in the passage
(D) citing evidence to support a view of Nightingale's career
(E) correcting a factual error occurring in one of the works under revie

RC 15.12

All of the cells in a particular plant start out with the
same complement of genes. How then can these cells
differentiate and form structures as different as roots,
stems, leaves, and fruits? The answer is that only a
(5) small subset of the genes in a particular kind of cell are
expressed, or turned on, at a given time. This is accomplished
by a complex system of chemical messengers
that in plants include hormones and other regulatory
molecules. Five major hormones have been identified:
(10) auxin, abscisic acid, cytokinin, ethylene, and gibberellin.
Studies of plants have now identified a new class ofregulatory molecules called oligosaccharins.
Unlike the oligosaccharins, the five well-known plant
hormones are pleiotropic rather than specific, that is,
(15) each has more than one effect on the growth and development
of plants. The five has so many simultaneous
effects that they are not very useful in artificially
controlling the growth of crops. Auxin, for instance,
stimulates the rate of cell elongation, causes shoots to
(20) grow up and roots to grow down, and inhibits the
growth of lateral shoots. Auxin also causes the plant to
develop a vascular system, to form lateral roots, and to
produce ethylene.
The pleiotropy of the five well-studied plant
(25) hormones is somewhat analogous to that of certain
hormones in animal. For example, hormones from the
hypothalamus in the brain stimulate the anterior lobe
of the pituitary gland to synthesize and release many
different hormones, one of which stimulates the release
(30) of hormones from the adrenal cortex. These hormones
have specific effects on target organs all over the body.
One hormone stimulates the thyroid gland, for
example, another the ovarian follicle cells, and so forth.
In other words, there is a hierarchy of hormones.
(35) Such a hierarchy may also exist in plants. Oligosaccharins
are fragments of the cell wall released by
enzymes: different enzymes release different oligosaccharins.
There are indications that pleiotropic plant
hormones may actually function by activating the
(40) enzymes that release these other, more specific chemical
messengers from the cell wall.


67. According to the passage, the five well-known plant hormones are not useful in controlling the growth of crops because
(A) it is not known exactly what functions the hormones perform
(B) each hormone has various effects on plants
(C) none of the hormones can function without the others
(D) each hormone has different effects on different kinds of plants
(E) each hormone works on only a small subset of a cell's genes at any particular time


68. The passage suggests that the place of hypothalamic hormones in the hormonal hierarchies of animals is similar to the
place of which of the following in plants?
(A) Plant cell walls
(B) The complement of genes in each plant cell
(C) A subset of a plant cell's gene complement
(D) The five major hormones
(E) The oligosaccharins


69. The passage suggests that which of the following is a function likely to be performed by an oligosaccharin?
(A) To stimulate a particular plant cell to become part of a plant's root system
(B) To stimulate the walls of a particular cell to produce other oligosaccharins
(C) To activate enzymes that release specific chemical messengers from plant cell walls
(D) To duplicate the gene complement in a particular plant cell
(E) To produce multiple effects on a particular subsystem of plant cells

70. The author mentions specific effects that auxin has on plant development in order to illustrate the
(A) point that some of the effects of plant hormones can be harmful
(B) way in which hormones are produced by plants
(C) hierarchical nature of the functioning of plant hormones
(D) differences among the best-known plant hormones
(E) concept of pleiotropy as it is exhibited by plant hormones

71. According to the passage, which of the following best describes a function performed by oligosaccharins?
(A) Regulating the daily functioning of a plant's cells
(B) Interacting with one another to produce different chemicals
(C) Releasing specific chemical messengers from a plant's cell walls
(D) Producing the hormones that cause plant cells to differentiate to perform different functions
(E) Influencing the development of a plant's cells by controlling the expression of the cells' genes

72. The passage suggests that, unlike the pleiotropic hormones, oligosaccharins could be used effectively to
(A) trace the passage of chemicals through the walls of cells
(B) pinpoint functions of other plant hormones
(C) artificially control specific aspects of the development of crops
(D) alter the complement of genes in the cells of plants
(E) alter the effects of the five major hormones on plant development

RC 15.11

At the end of the nineteenth century, a rising interest
in Native American customs and an increasing desire to
understand Native American culture prompted ethnologists
to begin recording the life stories of Native Amer-
(5) ican. Ethnologists had a distinct reason for wanting to
hear the stories: they were after linguistic or anthropological
data that would supplement their own field
observations, and they believed that the personal
stories, even of a single individual, could increase their
(10) understanding of the cultures that they had been
observing from without. In addition many ethnologists
at the turn of the century believed that Native American
manners and customs were rapidly disappearing,
and that it was important to preserve for posterity as
(15) much information as could be adequately recorded
before the cultures disappeared forever.
There were, however, arguments against this method
as a way of acquiring accurate and complete information.
Franz Boas, for example, described autobiogra-
(20) phies as being "of limited value, and useful chiefly for
the study of the perversion of truth by memory," while
232
Paul Radin contended that investigators rarely spent
enough time with the tribes they were observing, and
inevitably derived results too tinged by the investi-
(25) gator's own emotional tone to be reliable.
Even more importantly, as these life stories moved
from the traditional oral mode to recorded written
form, much was inevitably lost. Editors often decided
what elements were significant to the field research on a
(30) given tribe. Native Americans recognized that the
essence of their lives could not be communicated in
English and that events that they thought significant
were often deemed unimportant by their interviewers.
Indeed, the very act of telling their stories could force
(35) Native American narrators to distort their cultures, as
taboos had to be broken to speak the names of dead
relatives crucial to their family stories.
Despite all of this, autobiography remains a useful
tool for ethnological research: such personal reminis-
(40) cences and impressions, incomplete as they may be, are
likely to throw more light on the working of the mind
and emotions than any amount of speculation from an
ethnologist or ethnological theorist from another
culture.


61. Which of the following best describes the organization of the passage?
(A) The historical backgrounds of two currently used research methods are chronicled.
(B) The validity of the data collected by using two different research methods is compared.
(C) The usefulness of a research method is questioned and then a new method is proposed.
(D) The use of a research method is described and the limitations of the results obtained are discussed.
(E) A research method is evaluated and the changes necessary for its adaptation to other subject areas are
discussed.


62. Which of the following is most similar to the actions of nineteenth-century ethnologists in their editing of the life stories of
Native Americans?
(A) A witness in a jury trial invokes the Fifth Amendment in order to avoid relating personally incriminating evidence.
(B) A stockbroker refuses to divulge the source of her information on the possible future increase in a stock's value.
(C) A sports announcer describes the action in a team sport with which he is unfamiliar.
(D) A chef purposely excludes the special ingredient from the recipe of his prizewinning dessert.
(E) A politician fails to mention in a campaign speech the similarities in the positions held by her opponent for political
office and by herself.


63. According to the passage, collecting life stories can be a useful methodology because
(A) life stories provide deeper insights into a culture than the hypothesizing of academics who are not members of
that culture
(B) life stories can be collected easily and they are not subject to invalid interpretations
(C) ethnologists have a limited number of research methods from which to choose
(D) life stories make it easy to distinguish between the important and unimportant features of a culture
(E) the collection of life stories does not require a culturally knowledgeable investigator

64. Information in the passage suggests that which of the following may be a possible way to eliminate bias in the editing of
life stories?
(A) Basing all inferences made about the culture on an ethnological theory
(B) Eliminating all of the emotion-laden information reported by the informant
(C) Translating the informant's words into the researcher's language
(D) Reducing the number of questions and carefully specifying the content of the questions that the investigator can
ask the informant
(E) Reporting all of the information that the informant provides regardless of the investigator's personal opinion about
its intrinsic value


65. The primary purpose of the passage as a whole is to
(A) question an explanation
(B) correct a misconception
(C) critique a methodology
(D) discredit an idea
(E) clarify an ambiguity


66. It can be inferred from the passage that a characteristic of the ethnological research on Native Americans conducted
during the nineteenth century was the use of which of the following?
(A) Investigators familiar with the culture under study
(B) A language other than the informant's for recording life stories
(C) Life stories as the ethnologist's primary source of information
(D) Complete transcriptions of informants' descriptions of tribal beliefs
(E) Stringent guidelines for the preservation of cultural data

RC 15.10

Many United States companies have, unfortunately,
made the search for legal protection from import
competition into a major line of work. Since 1980 the
United States International Trade Commission (ITC)
(5) has received about 280 complaints alleging damage
from imports that benefit from subsidies by foreign
governments. Another 340 charge that foreign companies
"dumped" their products in the United States at
"less than fair value." Even when no unfair practices
(10) are alleged, the simple claim that an industry has been
injured by imports is sufficient grounds to seek relief.
Contrary to the general impression, this quest for
import relief has hurt more companies than it has
helped. As corporations begin to function globally, they
(15) develop an intricate web of marketing, production, and
research relationships, The complexity of these relationships
makes it unlikely that a system of import relief
laws will meet the strategic needs of all the units under
the same parent company.
(20) Internationalization increases the danger that foreign
companies will use import relief laws against the very
companies the laws were designed to protect. Suppose a
United States-owned company establishes an overseas
plant to manufacture a product while its competitor
(25) makes the same product in the United States. If the
competitor can prove injury from the imports---and
that the United States company received a subsidy from
a foreign government to build its plant abroad—the
United States company's products will be uncompeti230
(30) tive in the United States, since they would be subject to
duties.
Perhaps the most brazen case occurred when the ITC
investigated allegations that Canadian companies were
injuring the United States salt industry by dumping
(35) rock salt, used to de-ice roads. The bizarre aspect of the
complaint was that a foreign conglomerate with United
States operations was crying for help against a United
States company with foreign operations. The "United
States" company claiming injury was a subsidiary of a
(40) Dutch conglomerate, while the "Canadian" companies
included a subsidiary of a Chicago firm that was the
second-largest domestic producer of rock salt.


55. The passage is chiefly concerned with
(A) arguing against the increased internationalization of United States corporations
(B) warning that the application of laws affecting trade frequently has unintended consequences
(C) demonstrating that foreign-based firms receive more subsidies from their governments than United States firms
receive from the United States government
(D) advocating the use of trade restrictions for "dumped" products but not for other imports
(E) recommending a uniform method for handling claims of unfair trade practices

56. It can be inferred from the passage that the minimal basis for a complaint to the International Trade Commission is which
of the following?
(A) A foreign competitor has received a subsidy from a foreign government.
(B) A foreign competitor has substantially increased the volume of products shipped to the United States.
(C) A foreign competitor is selling products in the United States at less than fair market value.
(D) The company requesting import relief has been injured by the sale of imports in the United States.
(E) The company requesting import relief has been barred from exporting products to the country of its foreign
competitor.

57. The last paragraph performs which of the following functions in the passage?
(A) It summarizes the discussion thus far and suggests additional areas of research.
(B) It presents a recommendation based on the evidence presented earlier.
(C) It discusses an exceptional case in which the results expected by the author of the passage were not obtained.
(D) It introduces an additional area of concern not mentioned earlier.
(E) It cites a specific case that illustrates a problem presented more generally in the previous paragraph.

58. The passage warns of which of the following dangers?
(A) Companies in the United States may receive no protection from imports unless they actively seek protection from
import competition.
(B) Companies that seek legal protection from import competition may incur legal costs that far exceed any possible
gain.

(C) Companies that are United States-owned but operate internationally may not be eligible for protection from import
competition under the laws of the countries in which their plants operate.
(D) Companies that are not United States-owned may seek legal protection fro m import competition under United
States import relief laws.
(E) Companies in the United States that import raw materials may have to pay duties on those materials.

59. The passage suggests that which of the following is most likely to be true of United States trade laws?
(A) They will eliminate the practice of "dumping" products in the United States.
(B) They will enable manufacturers in the United States to compete more profitably outside the United States.
(C) They will affect United States trade with Canada more negatively than trade with other nations.
(D) Those that help one unit within a parent company will not necessarily help other units in the company.
(E) Those that are applied to international companies will accomplish their intended result.

60. It can be inferred from the passage that the author believes which of the following about the complaint mentioned in the
last paragraph?
(A) The ITC acted unfairly toward the complainant in its investigation.
(B) The complaint violated the intent of import relief laws.
(C) The response of the ITC to the complaint provided suitable relief from unfair trade practices to the complainant.
(D) The ITC did not have access to appropriate information concerning the case.
(E) Each of the companies involved in the complaint acted in its own best interest.

RC 15.9

Milankovitch proposed in the early twentieth century
that the ice ages were caused by variations in the Earth's
orbit around the Sun. For sometime this theory was
considered untestable, largely because there was no suffi-
(5) ciently precise chronology of the ice ages with which
the orbital variations could be matched.
To establish such a chronology it is necessary to
determine the relative amounts of land ice that existed
at various times in the Earth's past. A recent discovery
(10) makes such a determination possible: relative land-ice
volume for a given period can be deduced from the ratio
of two oxygen isotopes, 16 and 18, found in ocean sediments.
Almost all the oxygen in water is oxygen 16, but
a few molecules out of every thousand incorporate the
(15) heavier isotope 18. When an ice age begins, the continental
ice sheets grow, steadily reducing the amount of
water evaporated from the ocean that will eventually
return to it. Because heavier isotopes tend to be left
behid when water evaporates from the ocean surfaces,
(20) the remaining ocean water becomes progressively
enriched in oxygen 18. The degree of enrichment can
be determined by analyzing ocean sediments of the
period, because these sediments are composed of calcium
carbonate shells of marine organisms, shells that were
(25) constructed with oxygen atoms drawn from the surrounding
ocean. The higher the ratio of oxygen 18 to
oxygen 16 in a sedimentary specimen, the more land ice
there was when the sediment was laid down.
As an indicator of shifts in the Earth's climate, the
(30) isotope record has two advantages. First, it is a global
record: there is remarkably little variation in isotope
ratios in sedimentary specimens taken from different
continental locations. Second, it is a more continuous
record than that taken from rocks on land. Because of
(35) these advantages, sedimentary evidence can be dated
with sufficient accuracy by radiometric methods to
establish a precise chronology of the ice ages. The dated
isotope record shows that the fluctuations in global
ice volume over the past several hundred thousand years
(40) have a pattern: an ice age occurs roughly once every
100,000 years. These data have established a strong
connection between variations in the Earth's orbit and
the periodicity of the ice ages.
However, it is important to note that other factors,
(45) such as volcanic particulates or variations in the amount
of sunlight received by the Earth, could potentially have
affected the climate. The advantage of the Milankovitch
theory is that it is testable: changes in the Earth's orbit
can be calculated and dated by applying Newton's laws
(50) of gravity to progressively earlier configurations of the
bodies in the solar system. Yet the lack of information
about other possible factors affecting global climate does
not make them unimportant.

49. In the passage, the author is primarily interested in
(A) suggesting an alternative to an outdated research method
(B) introducing a new research method that calls an accepted theory into question
(C) emphasizing the instability of data gathered from the application of a new scientific method
(D) presenting a theory and describing a new method to test that theory
(E) initiating a debate about a widely accepted theory

50. The author of the passage would be most likely to agree with which of the following statements about the
Milankovitch theory?
(A) It is the only possible explanation for the ice ages.
(B) It is too limited to provide a plausible explanation for the ice ages, despite recent research findings.
(C) It cannot be tested and confirmed until further research on volcanic activity is done.
(D) It is one plausible explanation, though not the only one, for the ice ages.
(E) It is not a plausible explanation for the ice ages, although it has opened up promising possibilities for future
research.

51. It can be inferred from the passage that the isotope record taken from ocean sediments would be less useful to
researchers if which of the following were true?
(A) It indicated that lighter isotopes of oxygen predominated at certain times.
(B) It had far more gaps in its sequence than the record taken from rocks on land.
(C) It indicated that climate shifts did not occur every 100,000 years.
(D) It indicated that the ratios of oxygen 16 and oxygen 18 in ocean water were not consistent with those found in
fresh water.
(E) It stretched back for only a million years.

52. According to the passage, which of the following is true of the ratios of oxygen isotopes in ocean sediments?
(A) They indicate that sediments found during an ice age contain more calcium carbonate than sediments formed at
other times.
(B) They are less reliable than the evidence from rocks on land in determining the volume of land ice.
(C) They can be used to deduce the relative volume of land ice that was present when the sediment was laid down.
(D) They are more unpredictable during an ice age than in other climatic conditions.
(E) They can be used to determine atmospheric conditions at various times in the past.

53. It can be inferred from the passage that precipitation formed from evaporated ocean water has
(A) the same isotopic ratio as ocean water
(B) less oxygen 18 than does ocean water
(C) less oxygen 18 than has the ice contained in continental ice sheets
(D) a different isotopic composition than has precipitation formed from water on land
(E) more oxygen 16 than has precipitation formed from fresh water

54. It can be inferred from the passage that calcium carbonate shells
(A) are not as susceptible to deterioration as rocks
(B) are less common in sediments formed during an ice age
(C) are found only in areas that were once covered by land ice
(D) contain radioactive material that can be used to determine a sediment's isotopic composition
(E) reflect the isotopic composition of the water at the time the shells were formed