TOEFL iBT Reading Practice

[5] Ir has not been common at Earth’s surface since the very beginning of the planet’s history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth’s core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system’s original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. These calculations suggest that a period of about one million years would have been required. However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. So the unusually high concentration of Ir seems to require a special explanation.

Question: Paragraph 5 implies that a special explanation of the Ir in the boundary clay is needed because

• A-The Ir in microscopic meteorites reaching Earth during the Cretaceous period would have been incorporated into Earth’s core

• B-The Ir in the boundary clay was deposited much more than a million years ago

• C-The concentration of Ir in the boundary clay is higher than in microscopic meteorites

• D- The amount of Ir in the boundary clay is too great to have come from microscopic meteorites during the time the boundary clay was deposited

The Native American Trade is the trade between Europeans, their North American descendants, and the indigenous people of North America who are now known as Native Americans in the United States, First Nations in Canada, whom were formerly known as Indians. Indian Trade is the term used to describe the people involved in the trade, which began in the 1500s, and had various products in different regions and eras. In most of Canada the term is synonymous with the fur trade such as beaver fur which, from the European point of view, was the most valuable product of the trade.

Question: The word "indigenous" in paragraph 1 is closest in meaning to

• A-Intelligent

• B-Foreign

• C-Native

• D-Friendly

[1] Charles Darwin's Theory of Evolution is known as one of the most important and controversial scientific theories ever published. Natural selection contributes to the basis of Darwin's Theory of Evolution. One of the core tenets of Darwin's theory is that more offspring are always produced for a species than can possibly survive. Yet, no two offspring are perfectly alike. As a result, through random mutation and genetic drift, over time offspring develop new traits and characteristics. Over time beneficial traits and characteristics that promote survival will be kept in the gene pool while those that harm survival will be selected against. Therefore, this natural selection ensures that a species gradually improves itself over an extended duration of time. On the other hand, as a species continues to 'improve' itself, it branches out to create entirely new species that are no longer capable of reproducing together.

Question: The word 'those' in paragraph 1 refers to:

• A-Gene pool

• B-Survival

• C-Natural selection

• D-Traits characteristics

[4] Darwin's theory is that 'selective breeding' occurs in nature as 'natural selection' is the engine behind evolution. Thus, the theory provides an excellent basis for understanding how organisms change over time. Nevertheless, it is just a theory and elusively difficult to prove. One of the major holes in Darwin's theory revolves around “irreducibly complex systems.” An irreducibly complex system is known as a system where many different parts must all operate together. As a result, in the absence of one, the system as a whole collapses. Consequently, as modern technology improves, science can identify these “irreducibly complex systems” even at microscopic levels. These complex systems, if so inter-reliant, would be resistant to Darwin's supposition of how evolution occurs. As Darwin himself admitted, “To suppose that the eye with all its inimitable contrivances for adjusting the focus for different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I free confess, absurd in the highest degree.

what was the author's purpose of including a quote that the belief that the complexity of the human eye could have been formed by natural selection seems highly unlikely?

• A-To provide evidence that irreducibly complex systems exist

• B-The proof that the natural selection contradicts the basis of Darwin

• C-The support that the natural selection contributes to the basis of Darwin

• D-The support the claim that natural selection is just a theory and difficult to prove

[3] The first eye fossils date back to 540 million years ago. Prior to this time, organisms may have had use for light sensitivity, but not for fast locomotion and navigation by vision. However, it remains difficult to evaluate the rate of eye evolution because the fossil record of this period is weak. The development of the circular patch of photoreceptor cells into a fully functional vertebrate eye has been estimated on the rates of mutation, relative benefit to the organism and natural selection. Based on these estimations, it is suggested that it would take less than 364,000 years for the complete evolution of the eye.

Question: According to paragraph 3, how has the development of a fully functional vertebrate eye been estimated?

• A-It has been estimated on mutation rates, relative advantages to the organism and natural selection.

• B-It has been estimated on studies of the fossil record of this period.

• C-It has been estimated on natural selection only.

• D-It has been estimated based on the first eye fossils, dating back to 540 million years ago.

[4] Darwin's theory is that 'selective breeding' occurs in nature as 'natural selection' is the engine behind evolution. Thus, the theory provides an excellent basis for understanding how organisms change over time. Nevertheless, it is just a theory and elusively difficult to prove. One of the major holes in Darwin's theory revolves around “irreducibly complex systems.” An irreducibly complex system is known as a system where many different parts must all operate together. As a result, in the absence of one, the system as a whole collapses. Consequently, as modern technology improves, science can identify these “irreducibly complex systems” even at microscopic levels. These complex systems, if so inter-reliant, would be resistant to Darwin's supposition of how evolution occurs. As Darwin himself admitted, “To suppose that the eye with all its inimitable contrivances for adjusting the focus for different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I free confess, absurd in the highest degree.

Question: All of the following are mentioned in paragraph 4 as a viewpoint to state the natural selection is difficult to prove EXCEPT

• A-The belief that the complexity of the human eye could have been formed by natural selection seems highly unlikely

• B-The presence of irreducibly complex system contradicts how evolution occurs

• C-Modern microbiology proves that irreducibly complex systems exist

• D-Selective breeding is the major hole in the theory of natural selection

[4] Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.

Question: Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 4? Incorrect choices change the meaning in important ways or leave out essential information.

• A-The fossil record suggests that there was an abrupt extinction of many plants and animals at the end of the Mesozoic era.

• B-Few fossils of the Mesozoic era have survived in the rocks that mark the end of the Cretaceous.

• C-Fossils from the Cretaceous period of the Mesozoic up to the beginning of the Cenozoic era have been removed from the layers of rock that surrounded them.

• D-Plants and animals from the Mesozoic era were unable to survive in the Cenozoic era.

█ [A] Economic contact between Native Americans and Europeans can be traced back to the English and French fishermen off the coast of Canada in the 1500s. They traded guns and other weapons for beaver fur. █ [B] The first explorers to trade with the Native Americans were Giovanni da Verrazano and Jacques Cartier in the 1520s and 1530s. █ [C]In Verrazano's book he notes, "If we wanted to trade with them for some of their things, they would come to the seashore on some rocks where the breakers were most violent while we remained on the little boat █ [D]and they sent us what they wanted to give on a rope, continually shouting to us not to approach the land.

Question: In paragraph 5 of the passage, there is a missing sentence. The paragraph shows four letters (A, B, C, and D) that indicate where the following sentence could be added.

"Trade was difficult for the early Europeans trading with Native Americans during the first trades."

• A

• B

• C

• D

1 The city of Teotihuacán, which lay about 50 kilometers northeast of modern-day Mexico City, began its growth by 200 –100 B.C. At its height, between about A.D. 150 and 700, it probably had a population of more than 125,000 people and covered at least 20 square kilometers. It had over 2,000 apartment complexes, a great market, a large number of industrial workshops, an administrative center, a number of massive religious edifices, and a regular grid pattern of streets and buildings. Clearly, much planning and central control were involved in the expansion and ordering of this great metropolis. Moreover, the city had economic and perhaps religious contacts with most parts of Mesoamerica (modern Central America and Mexico).

In paragraph 1, each of the following is mentioned as a feature of the city ofTeotihuacán between A.D. 150 and 700 EXCEPT

• A- Regularly arranged streets

• B- Several administrative centers spread across the city

• C-Many manufacturing workshops

• D- Apartment complexes

2 How did this tremendous development take place, and why did it happen in the Teotihuacán Valley? Among the main factors are Teotihuacán’s geographic location on a natural trade route to the south and east of the Valley of Mexico, the obsidian1resources in the Teotihuacán Valley itself, and the valley’s potential for extensive irrigation. The exact role of other factors is much more difficult to pinpoint —for instance, Teotihuacán’s religious significance as a shrine, the historical situation in and around the Valley of Mexico toward the end of the first millennium B.C., the ingenuity and foresightedness of Teotihuacán’s elite, and, finally, the impact of natural disasters, such as the volcanic eruptions of the late first millennium B.C.

The word “ingenuity” in paragraph 2 is closest in meaning to

• A- Ambition

• B- Sincerity

• C- Faith

• D- Cleverness