1. Among the enduring legacies of the famous European voyages of discovery in the eighteenth and nineteenth centuries are a collection and scientific description of plants and animals from around the world. These form the nucleus of the great collections in modern museums and have been responsible for a radical revision in the way that we perceive the structure of Earth and the forces that have shaped its surface over time. As the fauna and flora from far-flung lands came to be described and incorporated into the body of knowledge about the world, it was noted that there were some striking similarities among living and extinct organisms of the Southern Hemisphere continents. In the 1840s, the English botanist Sir Joseph Dalton Hooker commented on the remarkable fact that the flora of South America and Oceania (mainly Australia, New Zealand, New Guinea, and the Malay Archipelago) shared seven families of flowering plants and 48 genera that were not to be found elsewhere. Later, similar patterns were observed in other groups of plants and animals, such as liverworts, lichens, mayflies, midges, and various types of vertebrates. How could these similarities be explained in view of the enormous stretches of ocean that separate the Southern Hemisphere continents today One idea developed during the late nineteenth century was that there existed in the remote geological past a vast Southern Hemisphere continentin other words, that the modern continents of the Southern Hemisphere were somehow connected long ago, thus explaining the similarities in fauna and flora.The name given to this hypothetical continent was Gondwana.
2. One of the most distinctive fossil plants of this hypothetical continent is called Glossopteris. When first described by the French paleobotanist Adolphe Brongniart in 1828, Glossopteris was thought to be a type of fern. Now, however, it is known to be a woody seed-bearing shrub or tree. The trunks of Glossopteris could reach 4 meters in height. Seeds and pollen-containing organs were borne in clusters at the tips of slender stalks attached to the leaves, but some species may have borne seeds in cones. It is thought that Glossopteris lived in a seasonal environment, and this is consistent with the occurrence of growth rings in the wood. Also, there is evidence that the plant was deciduous (that is, that it shed its leaves annually at the end of the growing season) and that it grew under very wet soil conditions, like the modern swamp cypress. The large leaves of Glossopteriswhich exceeded 30 centimeters in lengthare common fossils in rocks of the Permian period (299¨C251 million years ago) in India, Africa, South America, Australia, and Antarctica.
3. At the time the Gondwana hypothesis was conceived, the prevailing theory of Earth saw continents as fixed in their relative positions. The problem of linking up the various elements of Gondwana was solved by hypothesizing the existence of ancient land bridges. This changed in 1912 with the proposal of the theory of continental drift by the German meteorologist and geophysicist Alfred Wegener, an idea that was later developed and championed by the famous South African geologist Alex Logan du Toit. Wegener and du Toit argued that the continents are not fixed; rather, they have moved apart or drifted to their present-day positions. In the past, Gondwana was a single contiguous landmass comprising the present-day Southern Hemisphere continents.
4. These ideas seemed incredible at the time, but in support of their theory Wegener and du Toit pointed to similarities in fauna and flora, and the distributions of fossils such as Glossopteris provided an important piece of evidence in the assembly of the Gondwana jigsaw puzzle.Wegener and du Toit also drew together other different sources of evidence, such as the remarkable geometric fit of South America and Africa, and similarities between the ages and types of rock found in areas of Southern Hemisphere continents that are now thousands of miles apart. The notion of drifting continents only became widely accepted in the 1960s following the discovery of paleomagnetism (the study of changes in the polarity of Earth's magnetic field through time) and the development of the theory of plate tectonics, which explained the growth and movement of continents and other geological phenomena.
1..The word enduring in the passage is closest in meaning to
2..Why does the author mention the enormous stretches of ocean that separate the Southern Hemisphere continents today
A. To emphasize the importance of the famous European voyages of discovery in the eighteenth and nineteenth centuries
B. To suggest a reason why so many genera of flowering plants are found only in the Southern Hemisphere
C. To question the accuracy of Sir Joseph Dalton Hooker's observations about the similarities between the flora of Australia and that of South America
D. To explain why the similarities between flora pointed out by Sir Joseph Dalton Hooker seemed so remarkable
3..Which of the sentences below best expresses the essential information in the highlighted sentence in the passage Incorrect choices change the meaning in important ways or leave out essential information.
A. The similarities in fauna and flora across Southern Hemisphere continents were explained in the late nineteenth century.
B. In the nineteenth century it was discovered that the Southern Hemisphere continents contain fauna and flora that are highly similar.
C. In the nineteenth century, it was suggested that the modern continents of the Southern Hemisphere were once connected.
D. The fauna and flora of the modern continents of the Southern Hemisphere were found to be very similar in the late nineteenth century.
4..In paragraph 2, the author discusses Glossopteris in order to
A. provide an example of a fossil species that was attributed to Gondwana on the basis of its wide distribution
B. explain why the descriptions of ancient plants made by Adolphe Brongniart were not completely accurate
C. establish the importance of nineteenth-century paleobotanist Adolphe Brongniart
D. show that similarities among flora in the Southern Hemisphere continents were not limited to flowering plants
5..According to paragraph 2, current evidence indicates that Glossopteris had all of the following characteristics EXCEPT:
A. It was deciduous.
B. It was a type of fern.
C. It had large leaves.
D. It grew in wet soil conditions.
6..According to paragraph 2, what suggests that Glossopteris may have lived in a seasonal environment
A. It grew in what is now Antarctica.
B. It was a seed-bearing plant.
C. There is evidence that it lost its leaves annually.
D. There were stalks attached to its leaves.
7..The word prevailing in the passage is closest in meaning to
A. best understood
B. most controversial
C. generally accepted
D. recently proposed
8..According to paragraph 3, why did geologists initially hypothesize the existence of ancient land bridges across continents
A. To explain how the continents may have drifted to their present-day positions
B. To explain how organisms could spread across distant continents
C. To argue against Wegener's theory of continental drift
D. To help explain the present-day positions of the Southern Hemisphere continents
9..According to paragraph 3, what did Alfred Wegener and Alex Logan du Toit have in common
A. Both were originally trained as meteorologists.
B. Both had doubts about the hypothesis that Gondwana was once a single contiguous landmass.
C. Both believed that continents change their position over time.
D. Both believed that the present-day Southern Hemisphere continents were too far apart to have been linked by a land bridge.
10..The word incredible in the passage is closest in meaning to
C. hard to understand
D. impossible to believe
11..According to paragraph 4, Wegener and du Toit offered all of the following evidence in support of their hypothesis EXCEPT
A. distributions of fossils across the Southern Hemisphere continents
B. the geometric fit of South America and Africa
C. similarities in rocks across the Southern Hemisphere continents
D. differences in geological phenomena across the Southern Hemisphere continents
12..Paragraph 4 strongly suggests that the theory of continental drift was not widely accepted before the 1960s in part because
A. the distributions of fossils such as Glossopteris were not yet generally known
B. other explanations for the geometric fit of South America and Africa were available
C. there was no satisfactory explanation for the movement of continents
D. few scientists accepted the claims made by Wegener and du Toit about the similarities in the ages of groups of rocks
13..Look at the four squares that indicate where the following sentence could be added to the passage.
This led to its name, which means tongue fern in Greek and is a reference to its tongue-shaped leaves.
Where would the sentence best fit Click on a square to add the sentence to the passage.
14..Drag your choices to the spaces where they belong. To review the passage, click on View Text.
A. The plants and animals collected during the eighteenth- and nineteenth-century voyages of discovery made it possible to advance important scientific theories.
B. By 1828, fossils of Glossopteris had been discovered to have inhabited both the Northern and Southern Hemisphere continents in the remote geological past.
C. To explain the observed distribution patterns of flora and fauna, scientists hypothesized that land bridges had linked the widely separated Southern Hemisphere continents in the geological past.
D. The theory of continental drift, proposed in 1912, held that the Southern Hemisphere continents once formed an unbroken landmass and subsequently moved apart to their present locations.
E. To support their hypothesis that continents are not fixed in their relative positions, Alfred Wegener and Alex Logan du Toit used paleomagnetic evidence to develop the theory of plate tectonics.
F. Continental drift explained the distribution of organisms as well as the similarities in rocks and the geometric fit of Africa and South America, but the theory was not generally accepted until the 1960s.