Tools and hand bones excavated from the Swartkrans cave
complex in South Africa suggest that a close relative of early humans known as
Australopithecus robustus may have made and used primitive tools long before
the species became extinct I million
Line years ago. It may even have made and used primitive tools long
before humanity’s direct ancestor, Homo habilis, or “handy man,” began doing
so. Homo habilis and its successor, Homo erectus, coexisted with
Australopithecus robustus on the plains of South Africa for more than a million
years.
The Swartkrans cave in South Africa has been under
excavation since the 1940’s. The earliest fossil-containing layers of
sedimentary rock in the cave date from about 1.9 million years ago and contain
extensive remains of animals, primitive tools, and two or more species of
apelike hominids. The key recent discovery involved bones from the hand of
Australopithecus robustus, the first time such bones have been found.
The most important feature of the Australopithecus robustus
hand was the pollical distal thumb tip, the last bone in the thumb. The bone
had an attachment point for a “uniquely human” muscle, the flexor pollicis
longus, that had previously been found only in more recent ancestors. That
muscle gave Australopithecus robustutJ an opposable thumb, a feature that would
allow them to grip objects, including tools. The researchers also found
primitive bone and stone implements, especially digging tools, in the same
layers of sediments.
Australopithecus robustus were more heavily built- more
“robust” in anthropological terms-than their successors. They had broad faces,
heavy jaws, and massive crushing and grinding teeth that were used for eating
hard fruits, seeds, and fibrous underground plant parts. They walked upright,
which would have allowed them to carry and use tools. Most experts had
previously believed that Homo habilis were able to supplant Australopithecus
robustus because the former’s ability to use tools gave them an innate
superiority. The discovery that Australopithecus robustus also used tools means
that researchers will have to seek other explanations for their extinction.
Perhaps their reliance on naturally occurring plants led to their downfall as
the climate became drier and cooler, or perhaps Homo habilis, with their bigger
brains, were simply able tomake more sophisticated tools.
26. Where in the passage does the author mention the
materials from which tools were made?
(A) Lines 7-9
(B) Lines 12-13
(C) Lines 15-17
(D) Lines 21-23
Questions 27-38
The first two decades of this century were dominated by the
microbe hunters. These hunters had tracked down one after another of the
microbes responsible for the most dreaded scourges of many centuries:
tuberculosis, cholera, diphtheria. But there, remained some terrible diseases
for which no microbe could be incriminated: scurvy, pellagra, rickets,
beriberi. Then it was discovered that these diseases were caused by the lack of
vitamins, a trace substance in the diet. The diseases could be prevented or
cured by consuming foods that contained the vitamins. And so in the decades of
the 1920’s and 1930’s, nutrition became a science and the vitamin hunters
replaced the microbe hunters.
In the 1940’s and 1950’s, biochemists strived to learn why
each of the vitamins was essential for health. They discovered that key enzymes
in metabolism depend on one or another of the vitamins as coenzymes to perform
the chemistry that provides cells with energy for growth and function. Now,
these enzyme hunters occupied center stage.
You are aware that the enzyme hunters have been replaced by
a new breed of hunters who are tracking genes-the blueprints for each of the
enzymes-and are discovering the defective genes that cause inherited
diseases-diabetes, cystic fibrosis. These gene hunters, or genetic engineers,
use recombinant DNA technology to identify and clone genes and introduce them
into bacterial cells and plants to create factories for the massive production
of hormones and vaccines for medicine and for better crops for agriculture.
Biotechnology has become a multibillion-dollar industry.
In view of the inexorable progress in science, we can expect
that the gene hunters will be replaced in the spotlight. When and by whom?
Which kind of hunter will dominate the scene in the last decade of our waning
century and in the early decades of the next? I wonder whether the hunters who
will occupy the spotlight will be neurobiologists who apply the techniques of
the enzyme and gene hunters to the functions of the brain: What to call them? The
head hunters. I will return to them later.
27. What is the main topic of the passage?
(A) The microbe
hunters
(B) The potential of genetic engineering
(C) The progress of
modem medical research
(D) The discovery of
enzymes
28. The word “which” in line 4 refers to
(A) diseases
(B) microbe
(C) cholera
(D) diphtheria
29. The word “incriminated” in line 4 is closest in meaning
to
(A) investigated
(B) blamed
(C) eliminated
(D) produced
30. Which of the following can be cured by a change in diet?
(A) Tuberculosis
(B) Cholera
(C) Cystic fibrosis
(D) Pellagra
31. The word “strived” in line 9 is closest in meaning to
(A) failed
(B) tried
(C) experimented
(D) studied
32. How do vitamins influence health?
(A) They are necessary for some enzymes to
function.
(B) They protect the
body from microbes.
(C) They keep food
from spoiling.
(D) They are broken
down by cells to produce energy.
33. In the third paragraph, the author compares cells that
have been genetically altered by biotechnicians to
(A) gardens
(B) factories
(C) hunters
(D) spotlights
34. The word “them” in line 16 refers to
(A) cells and plants
(B) hormones
(C) genes
(D) gene hunters or
genetic engineers
35. The phrase “occupy the spotlight” in line 22 is closest
in meaning to
(A) receive the most attention
(B) go the furthest
(C) conquer territory
(D) lighten the load
36. The author implies that the most important medical
research topic of the future will be
(A) the functions of the brain
(B) inherited diseases
(C) the operation of
vitamins
(D) the structure of
genes
37. Which of the following best describes the author’stone
in the last paragraph of the passage?
(A) Critical
(B) Speculative
(C) Appreciative
(D) Emotional
38. With which of the following statements would the author
be most likely to agree?
(A) The focus of medical research will change in
the next two decades.
(B) Medical
breakthroughs often depend on luck.
(C) Medical research
throughout the twentieth century has been dominated by microbe hunters.
(D) Most diseases are
caused by defective genes.
Questions 39-50
In the mid-nineteenth century, the United States had
tremendous natural resources that could be exploited in order to develop heavy
industry. Most of the raw materials that are valuable in the manufacture of
machinery, transportation facilities, and consumer goods lay ready to be worked
into wealth. Iron, coal, and oil-the basic ingredients of industrial
growth-were plentiful and needed only the application of technical expertise,
organizational skill, and labor.
One crucial development in this movement toward
industrialization was the growth of the railroads. The railway network expanded
rapidly until the railroad map of the United States looked like a spider’s web,
with the steel filaments connecting all important sources of raw materials,
their places of manufacture, and their centers of distribution. The railroads
contributed to the industrial growth not only by connecting these major
centers, but also by themselves consuming enormous amounts of fuel, iron, and
coal.
Many factors influenced emerging modes of production. For
example, machine tools, the tools used to make goods, were steadily improved in
the latter part of the nineteenth century-always with an eye to speedier
production and lower unit costs. The products of the factories were rapidly
absorbed by the growing cities that sheltered the workers and the distributors.
The increased urban population was nourished by the increased farm production
that, in turn, was made more productive by the use of the new farm machinery.
American agricultural production kept up with the urban demand and still had
surpluses for sale to the industrial centers of Europe.
The labor that ran the factories and built the railways was
recruited in part from American farm areas where people were being displaced by
farm machinery, in part from Asia, and in part from Europe. Europe now began to
send tides of immigrants from eastern and southern Europe-most of whom were
originally poor farmers but who settled in American industrial cities. The
money to finance this tremendous expansion of the American economy still came
from European financiers for the most part, but the Americans were approaching
the day when their expansion could be financed in their own “money market.”
39. What does the passage mainly discuss?
(A) The history of
railroads in the United States
(B) The major United
States industrial centers
(C) Factors that affected industrialization in
the United States
(D) The role of
agriculture in the nineteenth century
40. The word “ingredients” in line 4 is closest in meaning
to
(A) minerals
(B) products
(C) methods
(D) components
41.Why does the author mention “a spider’s web” in line 8?
(A) To emphasize the
railroad’s consumption of oil and coal
(B) To describe the complex structure of the
railway system
(C) To explain the
problems brought on by railway expansion
(D) To describe the
difficulties involved in the distribution of raw materials
42. The word “themselves” in line 10 refers to
(A) sources
(B) centers
(C) railroads
(D) places
43. According to the passage, all of the following were true
of railroads in the United States in the nineteenth century EXCEPT that
(A) they connected
important industrial cities
(B) they were
necessary to the industrialization process
(C) they were
expanded in a short time
(D) they used relatively small quantities of
natural resources
44. According to the passage, what was one effect of the
improvement of machine tools?
(A) Lower manufacturing costs
(B) Better
distribution of goods
(C) More efficient
transportation of natural resources
(D) A reduction in
industrial jobs
45. According to the passage, who were the biggest consumers
of manufactured products?
(A) Railway workers
(B) Farmers
(C) City dwellers
(D) Europeans
46. The word “nourished” in line 16 is closest in meaning to
(A) protected
(B) fed
(C) housed
(D) paid
47. Which of the following is NOT true of United States
farmers in the nineteenth century?
(A) They lost some
jobs because of mechanization.
(B) They were unable to produce sufficient food for
urban areas.
(C) They raised their
productivity by using new machinery.
(D) They sold food to
European countries.
48. According to the passage, what did the United States
supply to European cities?
(A) Machine tools
(B) Money
(C) Raw materials
(D) Agricultural produce
49. The word “ran” in line 19 is closest in meaning to
(A) operated
(B) hurried
(C) constructed
(D) owned
50. Where in the passage does the author mention the
financial aspect of industrial expansion?
(A) Lines 1-2
(B) Lines 9-11
(C) Lines 17-18
(D) Lines 22-25
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