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TOEFL Reading 1

 

 

Directions

In this section, you will read three passages and answer reading comprehension questions about each passage. Most questions are worth one point, but the last question in each set is worth more than one point. The directions indicate how many points you may receive.
You have 60 minutes to read all of the passages and answer the questions. Some passages include a word or phrase followed by an asterisk (*). Go to the bottom of the page to see a definition or an explanation of these words or phrases.


Questions 1-12


Causes of Ice Ages

Geologists have shown that for about 80 percent of the past 2.5 million years, ice-age conditions have prevailed on the Earth's surface. During the past one million years, increased glacial conditions have run in cycles of approximately 100,000 years.
Many different factors may contribute to these increases in glaciation at regular intervals throughout Earth's more geologically recent history. The three most prominent factors probably relate to the amount of sunlight that reaches the Earth. This varies over time for three main reasons. First, the planet wobbles* as it spins, due to the pull of the sun and moon. Furthermore, the Earth tilts* on its axis and the degree of tilt changes over time. Finally, the orbit of the Earth around the sun is elliptical and the length of the major axis of the ellipse changes over a period of about 100,000 years. A mathematician named Milutin Milankovitch discovered in the 1930s that the pattern of insolation, or sunlight, predicted by these eccentricities in the Earth's movement matched the period of the last several eras of intense glaciation.
These Milankovitch insolation cycles were the dominant theory in ice-age research for much of the twentieth century despite the fact that the match between periods of peak insolation and most intense glaciation were not exact. For example, a cycle of 400,000 years predicted by the Milankovitch theory has never shown up in the climate records obtained through the study of microfossils deposited on the sea floor. Also, recent analysis has shown that the insolation theory predicts peaks of sunlight at intervals of 95,000 and 125,000 years. Climatological data does not support this predicted sunlight peaking. Other damaging evidence was the indication of a precisely measured sudden rise in temperature at a water-filled cave in Nevada, which preceded the increase in solar radiation that was supposed to cause it.
These and other problems with the Milankovitch cycles led some researchers to seek alternative explanations for the cyclic arrival of extended ice ages. In the 1990s, it was discovered that the orbital inclination of the Earth to the sun and planets could also be responsible for climate changes. If we imagine a flat plane with the sun in the center and the planets revolving around it, the Earth slowly moves in and out of the flat plane by a few degrees, repeating the cycle every 100,000 years. Two scientists, Muller and MacDonald, have proposed that it is this orbital inclination which is ultimately responsible for the periods of glaciation and warming. They argue that because of the oscillation, the Earth periodically travels through clouds of debris, in the form of dust and meteoroids. Such debris could reduce the amount of solar energy reaching the surface of our planet, thus plunging it into regular cold periods.
The advantage of this theory is that it is not confronted with several of the problems associated with the Milankovitch theory. In particular, the new theory fits well with the analysis of ocean sediments taken from eight locations around the world. This analysis yielded data clearly showing the peak of the last several ice ages with a period of 100,000 years and corresponding to the periods when the Earth's oscillating inclination takes it through clouds of extraterrestrial debris.
However, many researchers in this field are not yet persuaded by the inclination hypothesis. The main problem is that the amount of dust that falls to the ground when the Earth travels through space debris is relatively small - not enough to produce radical climate changes. Volcanic eruptions, for example, release much greater amounts of ash and dust and have relatively little effect on climate. Supporters have countered that the by-products created by the dust as it vaporizes on entering the atmosphere cause subtle changes to the energy levels. Nevertheless, the necessary physical proof has yet to be found to convince the skeptics.

*wobble: to shake or move from side to side
*tilt: to be in a sloping position 


  1. The word "prevaied" in the passage is closest in meaning to 

    ruled
    existed 
    survived 
    triumphed


    Geologists have shown that for about 80 percent of the past 2.5 million years, ice-age conditions have prevailed on the Earth's surface. During the past one million years, increased glacial conditions have run in cycles of approximately 100,000 years.


    2. What can be inferred from paragraph 2 about the factors that contribute to glaciation? 

    They affect the Earth's spin.
    They are geologically recent.
    Оnly three factors relate to levels of sunlight.
    Other factors than those relating to the sunlight affect ice buildup.

    Paragraph 2 is marked with an arrow [->].


    -> Many different factors may contribute to these increases in glaciation at regular intervals throughout Earth's more geologically recent history. The three most prominent factors probably relate to the amount of sunlight that reaches the Earth. This varies over time for three main reasons. First, the planet wobbles as it spins, due to the pull of the sun and moon. Furthermore, the Earth tilts on its axis and the degree of tilt changes over time. Finally, the orbit of the Earth around the sun is elliptical and the length of the major axis of the ellipse changes over a period of about 100,000 years. A mathematician named Milutin Milankovitch discovered in the 1930s that the pattern of insolation, or sunlight, predicted by these eccentricities in the Earth's movement matched the period of the last several eras of intense glaciation.


    3. The phrase "these eccentricities" in the passage refers to all of the following EXCEPT 

    the various movements of the Earth as it spins 
    the degree of change in the Earth's tilt over time 
    the pattern of insolation matching the Earth's movement 
    the changing distance to the sun during the Earth's elliptical orbit


    Many different factors may contribute to these increases in glaciation at regular intervals throughout Earth's more geologically recent history. The three most prominent factors probably relate to the amount of sunlight that reaches the Earth. This varies over time for three main reasons. First,
    the planet wobbles as it spins, due to the pull of the sun and moon. Furthermore, the Earth tilts on its axis and the degree of tilt changes over time. Finally, the orbit of the Earth around the sun is elliptical and the length of the major axis of the ellipse changes over a period of about 100,000 years. A mathematician named Milutin Milankovitch discovered in the 1930s that the pattern of insolation, or sunlight, predicted bythese eccentricities in the Earth's movement matched the period of the last several eras of intense glaciation.


    4. Scientists accepted the Milankovitch theory even though 

    the peaks of sunlight occurred at intervals of 95.000 and 125.000 years 
    the peaks of insolation and intense glaciation did not match 
    there were climate records of a 400,000-year cycle
    there were microfossil deposits on the sea floor


    [Refer to the full passage]


    5. In paragraph 4, why does the author suggest the image of a flat plane? 

    To help the reader visualize the positions and movements of the heavenly bodies
    To demonstrate to the reader how the Earth orbits the sun 
    To support the argument that the orbital inclination increases tilting 
    To show how the Milankovitch theory doesn't explain the cyclical changes in climate

    Paragraph 4 is marked with an arrow ->.


    -> These and other problems with the Milankovitch cycles led some researchers to seek alternative explanations for the cyclic arrival of extended ice ages. In the 1990s, it was discovered that the orbital inclination of the Earth to the sun and planets could also be responsible for climate changes. If we imagine a flat plane with the sun in the center and the planets revolving around it, the Earth slowly moves in and out of the flat plane by a few degrees, repeating the cycle every 100,000 years. Two scientists. Muller and MacDonald, have proposed that it is this orbital inclination which is ultimately responsible for the periods of glaciation and warming. They argue that because of the oscillation. the Earth periodically travels through clouds of debris, in the form of dust and meteoroids. Such debris could reduce the amount of solar energy reaching the surface of our planet, thus plunging it into regular cold periods.


    6. The word "it" in the passage refers to 

    such debris 
    solar energy 
    the surface 
    our planet


    These and other problems with the Milankovitch cycles led some researchers to seek alternative explanations for the cyclic arrival of extended ice ages. In the 1990s, it was discovered that the orbital inclination of the Earth to the sun and planets could also be responsible for climate changes. If we imagine a flat plane with the sun in the center and the planets revolving around it, the Earth slowly moves in and out of the flat plane by a few degrees, repeating the cycle every 100,000 years. Two scientists. Muller and MacDonald, have proposed that it is this orbital inclination which is ultimately responsible for the periods of glaciation and warming. They argue that because of the oscillation, the Earth periodically travels through clouds of debris, in the form of dust and meteoroids. Such debris could reduce the amount of solar energy reaching the surface of our planet. thus plunging it into regular cold periods.


    7. In paragraph 4, the author explains that 

    Milankovitch did not know about the orbital inclination of the Earth
    glaciation occurs when the orbital inclination has entered a new cycle
    the Earth always travels through clouds of debris after moving out of the plane by a few degrees
    the amount of solar energy reaching the Earth's surface causes the changes of temperature

    Paragraph 4 is marked with an arrow [->].


    -> These and other problems with the Milankovitch cycles led some researchers to seek alternative explanations for the cyclic arrival of extended ice ages. In the 1990s, it was discovered that the orbital inclination of the Earth to the sun and planets could also be responsible for climate changes. If we imagine a flat plane with the sun in the center and the planets revolving around it, the Earth slowly moves in and out of the flat plane by a few degrees, repeating the cycle every 100,000 years. Two scientists. Muller and MacDonald, have proposed that it is this orbital inclination which is ultimately responsible for the periods of glaciation and warming. They argue that because of the oscillation, the Earth periodically travels through clouds of debris, in the form of dust and meteoroids. Such debris could reduce the amount of solar energy reaching the surface of our planet. thus plunging it into regular cold periods.


    8. What problem in the Milankovitch theory was mentioned as being explained by the Muller and MacDonald theory? 

    The climate records obtained by studying microfossil deposits not matching his predicted cycle
    The irregularities of the Earth's movements through orbital inclinations not following any pattern
    The Earth's spin wobbling in relation to the Earth's oscillating inclination
    The peak in the ice ages occurring at intervals between 95,000 and 125,000 years instead of 400,000


    [Refer to the full passage.]


    9. The word "persuaded" in the passage is closest in meaning to 

    convinced
    discouraged
    affected
    challenged


    However, many researchers in this field are not yetpersuaded by the inclination hypothesis. The main problem is that the amount of dust that falls to the ground when the Earth travels through space debris is relatively small -not enough to produce radical climate changes. Volcanic eruptions, for example, release much greater amounts of ash and dust and have relatively little effect on climate. Supporters have countered that the by-products created by the dust as it vaporizes on entering the atmosphere cause subtle changes to the energy levels. Nevertheless, the necessary physical proof has yet to be found to convince the skeptics.


    10. What problem is associated with the Muller and MacDonald theory? 

    The amount of debris that is released from volcanoes is proportional to the amount of interstellar dust.
    The amount of ash from volcanoes and space dust that vaporizes in the atmosphere is itoo small. 
    The amount of dust entering the atmosphere is less than the amount of ash and dust released by volcanoes.
    The by-products created by vaporized space dust cause relevant changes to the energy levels.


    [Refer to the full passage.]


    11. Look at the four squares [?] that indicate where the following sentence could be added to the passage. 

    When the Earth is at its furthest from the sun, less sunlight reaches the surface.

    Where would the sentence best fit?

    Choose the letter of the square that shows where the sentence should be added.
     A
     B
     C
     D


    Many different factors may contribute to these increases in glaciation at regular intervals throughout Earth's more geologically recent history. [A] The three most prominent factors probably relate to the amount of sunlight that reaches the Earth. This varies over time for three main reasons. First. the planet wobbles as it spins, due to the pull of the sun and moon. [B] Furthermore, the Earth tilts on its axis and the degree of tilt changes over time. [C] Finally, the orbit of the Earth around the sun is elliptical and the length of the major axis of the ellipse changes over a period of about 100,000 years. [D] A mathematician named Milutin Milankovitch discovered in the 1930s that the pattern of insolation, or sunlight, predicted by these eccentricities in the Earth's movement matched the period of the last several eras of intense glaciation.


    12. Directions: Select the appropriate phrases from the answer choices and match them to the flaws in the ice-age theories to which they relate. TWO of the answer choices will NOT be used. This question is worth 4 points.
    Write the letters of the answer choices in the spaces where they belong. 
    Refer to the full passage.

    Answer Choices
    A) Data of climate records not coinciding with predicted intervals of sunlight
    B) Temperature rises occurring before the increase of sunlight
    C) The irregularities of the Earth's movement during its orbit around the sun
    D) The inconsistency between the periods of sunlight and glaciation
    E) The relatively mild effect of volcanic eruptions on the climate
    F} The orbital inclination of Earth through clouds of debris
    G) The relatively small amount of interstellar debris reaching Earth
    H) The lack of clear support from ocean sediment data
    I) The lack of physical evidence in support of the effects of the inclination hypothesis

    Flaws in the Milankovitch Cycles Theory

    Flaws in the Muller and MacDonald Theory


    Questions 13-26
Bird Migration
The phenomenon of seasonal bird migration has been known about for thousands of years, but it is still not fully understood by scientists. Not all birds migrate, but generally speaking the more northerly the breeding ground, the more likely is it that a species will migrate south for the winter. The main reason for this annual shifting of residence is that during the northern winters food becomes scarce and the cold temperatures make survival difficult. Some species are well adapted to these harsh conditions, but for those that aren't, moving south to warmer conditions is advantageous.
Changes in the weather can trigger the start of the journey south, although birds in the Northern Hemisphere seem to know when it is time to migrate south before the winter. In some species at least, the changes in the length of the day cause glands in the birds' bodies to secrete hormones that produce other changes, which ready the birds for the long flight south. At this time fat starts to accumulate under the skin, and this provides a store of energy for the long flight when they will be expending more calories flying than they can obtain during their brief rest stops.
In fact, bird-migration patterns are more complex than the simple pattern implied above. 3irds that breed in the Southern Hemisphere migrate north to wintering grounds. Other birds travel on an approximately east-west path since milder climates can often be found n coastal areas of continental regions. Some birds find conditions more suitable at lower altitudes in a mountainous region and so migrate to lower levels in winter.
Perhaps the most mysterious and as yet not totally understood aspect of bird migration is how birds can navigate such long distances and arrive so precisely at their destination. Various possibilities exist. The most obvious explanation is that they learn the topographic* features of their route. However, it is not feasible that this method could be used for crossing larger stretches of water or very long trips across whole continents. Another possible explanation is that some birds may use magnetic fields. Scientists have actually detected tiny crystals of magnetite in the olfactory* tract of some species, and homing pigeons have been shown to follow magnetic field lines of the Earth.
A further possibility is that birds can detect the polarization patterns in sunlight. Some light waves from the sun are absorbed in the atmosphere, and some pass through. The resulting pattern of light waves forms a large bowtie-shaped image in the sky. The image has fuzzy ends and is sometimes known as Haidinger's brush after the discoverer of the effect. The mage is oriented in a north and south direction and is visible at sunset. Although birds may not see this shape, they can discern gradations of polarization, which give them a kind of compass for determining directions.
Scientists believe that some birds navigate by use of star positions; this has been established with at least one species. In a series of studies, caged birds were subjected to the projection of the nighttime Northern Hemisphere inside a planetarium. All stars rotate around Polaris, the pole star, and this movement seemed to give the birds the information they needed to orientate themselves in the correct direction. However, some recent research contradicts this. Perhaps it is not the lack of movement of the pole star but rather the constellation patterns that guide them. It has also been found that when fewer stars were visible on the planetarium ceiling, the birds' sense of direction became poorer. And this, too. implies that the general star pattern does have some bearing on orientation.
The current state of research suggests that all of the above-mentioned methods probably nave an influence on bird migration. Different species use one, some, or even all methods at different times and in various situations.

*topographic: relating to the natural features of land 
*olfactory: connected with the sense of smell


  1. In paragraph 1, it is understood that some birds don't migrate south in the winter because they 

    already live in warmer conditions
    live in areas that have an abundant food supply 
    have difficulty surviving the frigid temperatures 
    are suited to the difficult conditions

    Paragraph 1 is marked with an arrow [->].


    -> The phenomenon of seasonal bird migration has been known about for thousands of years, but it is still not fully understood by scientists. Not all birds migrate, but generally speaking the more northerly the breeding ground, the more likely is it that a species will migrate south for the winter. The main reason for this annual shifting of residence is that during the northern winters food becomes scarce and the cold temperatures make survival difficult. Some species are well adapted to these harsh conditions, but for those that aren't, moving south to warmer conditions is advantageous.


    14. The word "those" in the passage refers to 

    northern winters
    cold temperatures
    harsh conditions
    some bird species


    The phenomenon of seasonal bird migration has been known about for thousands of years, but it is still not fully understood by scientists. Not all birds migrate, but generally speaking the more northerly the breeding ground, the more likely is it that a species will migrate south for the winter. The main reason for this annual shifting of residence is that during the northern winters food becomes scarce and the cold temperatures make survival difficult. Some species are well adapted to these harsh conditions, but for those that aren't, moving south to warmer conditions is advantageous.


    15. According to paragraph 2, what are the results of changes in the weather? 

    The change in the length of the day
    The secretion of hormones by the birds
    The expenditure of calories 
    The onset of migration

    Paragraph 2 is marked with an arrow [->].


    -> Changes in the weather can trigger the start of the journey south, although birds in the Northern Hemisphere seem to know when it is time to migrate south before the winter. In some species at least, the changes in the length of the day cause glands in the birds' bodies to secrete hormones that produce other changes, which ready the birds for the long flight south. At this time fat starts to accumulate under the skin, and this provides a store of energy for the long flight when they will be expending more calories flying than they can obtain during their brief rest stops.


    16. The word "accumulate'' in the passage is closest in meaning to 

    build up
    fill in 
    break up
    cut back


    Changes in the weather can trigger the start of the journey south, although birds in the Northern Hemisphere seem to know when it is time to migrate south before the winter. In some species at least, the changes in the length of the day cause glands in the birds' bodies to secrete hormones that produce other changes, which ready the birds for the long flight south. At this time fat starts to accumulate under the skin, and this provides a store of energy for the long flight when they will be expending more calories flying than they can obtain during their brief rest stops.


    17. All of the bird migration patterns are mentioned in the passage EXCEPT 

    the migration north from the Southern Hemisphere
    the migration east or west toward milder climates 
    the migration from mountainous regions to lower altitudes
    the migration from east to west towards hotter climates.


    [Refer to the full passage.]


    18. The word "precisely" in the passage is closest in meaning to 

    finally
    exactly
    entirely
    decisively


    Perhaps the most mysterious and as yet not totally understood aspect of bird migration is how birds can navigate such long distances and arrive so precisely at their destination. Various possibilities exist. The most obvious explanation is that they learn the topographic features of their route. However, it is not feasible that this method could be used for crossing larger stretches of water or very long trips across whole continents. Another possible explanation is that some birds may use magnetic fields. Scientists have actually detected tiny crystals of magnetite in the olfactory tract of some species, and homing pigeons have been shown to follow magnetic field lines of the Earth.


    19. It can be inferred that polarization patterns 

    absorb sunlight
    are tied in the center
    are invisible at night 
    cause a magnetic force


    [Refer to the full passage.]


    20. Why does the author mention Haidinger's brush? 

    To understand the phenomenon
    To describe the pattern
    To explain what birds see
    To define the fuzzy ends


    [Refer to the full passage.]


    21. The word "subjected" in the passage is closest in meaning to 

    exposed
    subjugated 
    constrained
    invited


    Scientists believe that some birds navigate by use of star positions; this has been established with at least one species. In a series of studies, caged birds were subjectedto the projection of the nighttime Northern Hemisphere inside a planetarium. All stars rotate around Polaris, the pole star, and this movement seemed to give the birds the information they needed to orientate themselves in the correct direction. However, some recent research contradicts this. Perhaps it is not the lack of movement of the pole star but rather the constellation patterns that guide them. It has also been found that when fewer stars were visible on the planetarium ceiling, the birds' sense of direction became poorer. And this, too, implies that the general star pattern does have some bearing on orientation.


    22. According to paragraph 6, how do some birds navigate during the night? 

    By using a projection of the star positions
    By circling around the pole star
    By orientating themselves using the constellations 
    By getting their bearings from a few visible stars

    Paragraph 6 is marked with an arrow [->].


    -> Scientists believe that some birds navigate by use of star positions; this has been established with at least one species. In a series of studies, caged birds were subjected to the projection of the nighttime Northern Hemisphere inside a planetarium. All stars rotate around Polaris, the pole star, and this movement seemed to give the birds the information they needed to orientate themselves in the correct direction. However, some recent research contradicts this. Perhaps it is not the lack of movement of the pole star but rather the constellation patterns that guide them. It has also been found that when fewer stars were visible on the planetarium ceiling, the birds' sense of direction became poorer. And this, too, implies that the general star pattern does have some bearing on orientation.


    23. 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. 

    Birds needing to orientate themselves in the right direction seemed to use the information they get from the stars that rotate around Polaris.
    The pole star seemed to be used by birds to get the information they needed because they were able to orientate themselves using the star's rotation in the correct direction.
    Birds needing to correct the Polaris direction in which to orientate themselves seemed to use the fact that all stars rotate.
    The stars rotating in the correct direction around the pole star is what seemed to give the birds the information they needed for orientating themselves to Polaris.


    Scientists believe that some birds navigate by use of star positions; this has been established with at least one species. In a series of studies, caged birds were subjected to the projection of the nighttime Northern Hemisphere inside a planetarium. All stars rotate around Polaris, the pole star. and this movement seemed to give the birds the information they needed to orientate themselves in the correct direction. However, some recent research contradicts this. Perhaps it is not the lack of movement of the pole star but rather the constellation patterns that guide them. It has also been found that when fewer stars were visible on the planetarium ceiling, the birds' sense of direction became poorer. And this, too, implies that the general star pattern does have some bearing on orientation.


    24. The word "this" in the passage refers to 

     The number of stars that were visible
    The relative loss of the birds' sense of direction
    The constellation patterns that guide birds
    The pole star's stationary position


    Scientists believe that some birds navigate by use of star positions; this has been established with at least one species. In a series of studies, caged birds were subjected to the projection of the nighttime Northern Hemisphere inside a planetarium. All stars rotate around Polaris, the pole star. and this movement seemed to give the birds the information they needed to orientate themselves in the correct direction. However, some recent research contradicts this. Perhaps it is not the lack of movement of the pole star but rather the constellation patterns that guide them. It has also been found that when fewer stars were visible on the planetarium ceiling, the birds' sense of direction became poorer. Andthis, too, implies that the general star pattern does have some bearing on orientation.


    25. Look at the four squares [?] that indicate where the following sentence could be added to the passage. 

    Over short distances the birds could recognize particular landscapes such as river valleys and shapes of hills.

    Where would the sentence best fit?

    Choose the letter of the square that shows where the sentence should be added.
     A
     B
     C
     D


    Perhaps the most mysterious and as yet not totally understood aspect of bird migration is how birds can navigate such long distances and arrive so precisely at their destination. Various possibilities exist. [A] The most obvious explanation is that they learn the topographic features of their route. [B] However, it is not feasible that this method could be used for crossing larger stretches of water or very long trips across whole continents. [C] Another possible explanation is that some birds may use magnetic fields. [D]Scientists have actually detected tiny crystals of magnetite in the olfactory tract of some species, and homing pigeons have been shown to follow magnetic field lines of the Earth.


    26. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
    Write the tetters of the answer choices in the spaces where they belong.
    Refer to the full passage.

    Scientists have proposed several methods that birds use for orientating themselves during their seasonal migrations.





    Answer Choices

    A) Birds not only migrate north or south depending on which hemisphere they live in, but they also migrate along coastal regions or in and out of mountainous areas.
    B) Birds' ability to detect gradations of polarization patterns in sunlight could give them a way for determining directions.
    C) Changes in both the weather and the length of day can cause the birds' bodies to make physical changes to prepare them for the long flights.
    D) The principal reason for birds to migrate is that most bird species are not adapted to the harsh winter conditions and the scarcity of food during that season.
    E) The star patterns and the way the stars rotate around the fixed position of the pole star could give birds the direction in which to navigate.
    F) Birds may use their knowledge of the features of the landscape, although this seems unlikely given the distances that birds migrate.

    Questions 27-39
Radon
Radon is a radioactive gas that is invisible and odorless. It forms during the decay of uranium-238, and in decaying, itself produces solid heavy metal radioactive particles of polonium, lead, and bismuth. The parent element, uranium, is distributed in rocks and soils in -any regions of the world, although usually in negligible* amounts. However, concentrations of this element occur in certain rocks, and under certain conditions it is dissolved by underground water and carried over great distances before seeping into other rocks and soils.
Since radon is a gas, it can move from the ground into the air, where it is dispersed by the winds. If it infiltrates buildings, however, it can build up over time and lead to serious health problems. In fact, the radon itself is chemically inert and so does not enter into chemical reactions with other substances. It is readily dissolved in blood and circulates through the body until it is expelled, usually before it has had time to decay. The health problems associated with radon activity arise from the radioactive products of its disintegration. mentioned above.
The products of the decay process, especially polonium-218 and polonium-214, emit radiation, which kills or damages living cells, causing genetic mutations and cancer. These radon progeny are not dispersed harmlessly like radon itself but accumulate as the radon decays. Outside the body, these solid materials can attach themselves to dust particles and surfaces throughout a building and then be inhaled. The decay products can also stick to tobacco leaves during growth and then enter the body when the tobacco is smoked. Inside the body these dangerous by-products of radon become lodged in lung tissue and the bronchial tubes. As these decay, they emit alpha and beta particles and gamma rays. Of these, the alpha particles can do the most damage since they are the bulkiest of the three and therefore cannot penetrate very far into living tissue. Because of this relative immobility, concentrations of the particle form and damage cells in the immediate area. Beta particles and gamma rays are less dangerous since they travel further and are less concentrated in the tissues.
The primary way that radon penetrates buildings is through foundations. It enters through cracks in basement floors, drains, loose-fitting pipes, and exposed soil areas. Radon also finds its way into water, although if the water is exposed to the atmosphere or agitated, the radon disperses into the air. Because of this, concentrations of this uranium daughter are not high in rivers, but water drawn from underground sources into homes can have elevated levels.
The chief health risk from inhaling radon or its daughter products is lung cancer. Scientists have concluded that exposure to this carcinogen is the second leading cause of this disease in the United States. Major scientific organizations believe it contributes to approximately 12 percent of the incidence in the United States alone. It is true that some research has cast doubt on the likelihood of residential radon accumulations contributing to cancer rates. Other larger scale studies contradict the neutral findings. For example, a recent study of 68,000 underground miners who were exposed to high levels of radon shows that they are five times more likely to die of lung cancer than the general population. Smokers, whose incidence of lung cancer is significantly higher than the nonsmoking population, are even more at risk if they are exposed to high levels of radon.
It is now possible to have buildings tested for radon accumulation. In an average home, this is about 1.3 picocuries* per liter, which is considered an acceptable although not a totally safe level. If these levels are above 4 picocuries per liter of air, then homeowners are advised to reduce the amount seeping into the living space. This can be achieved through various means including concrete sealing and the installation of active ventilation systems. It is not possible to completely eradicate traces of radon since the natural outdoors level averages 0.4 picocuries per liter, but minimizing the amount is a prudent preventative measure.

*negligible: too small to be important 
*picocurie: a level of radiation activity


  1. The phrase "this element" in the passage refers to 

    lead
    radon
    uranium
    polonium


    Radon is a radioactive gas that is invisible and odorless. It forms during the decay of uranium-238, and in decaying. itself produces solid heavy metal radioactive particles of polonium, lead, and bismuth. The parent element, uranium, is distributed in rocks and soils in many regions of the world, although usually in negligible amounts. However, concentrations of this element occur in certain rocks, and under certain conditions it is dissolved by underground water and carried over great distances before seeping into other rocks and soils.


    28. The word "seeping" in the passage is closest in meaning to 

    leaking
    spilling
    releasing
    erupting


    Radon is a radioactive gas that is invisible and odorless. It forms during the decay of uranium-238, and in decaying, itself produces solid heavy metal radioactive particles of polonium, lead, and bismuth. The parent element, uranium, is distributed in rocks and soils in many regions of the world, although usually in negligible amounts. However, concentrations of this element occur in certain rocks, and under certain conditions it is dissolved by underground water and carried over great distances before seeping into other rocks and soils.


    29. In paragraph 2, what can be inferred about the relationship of radon and health problems? 

    The gas has to have time to decay in order to cause health problems. 
    Since radon is chemically inert, it cannot lead to health problems.
    As a gas, radon disperses in the wind and consequently isn't a health problem.
    The gas has to disintegrate before it can seep into buildings.

    Paragraph 2 is marked with an arrow [->].


    -> Since radon is a gas, it can move from the ground into the air, where it is dispersed by the winds. If it infiltrates buildings, however, it can build up over time and lead to serious health problems. In fact, the radon itself is chemically inert and so does not enter into chemical reactions with other substances. It is readily dissolved in blood and circulates through the body until it is expelled, usually before it has had time to decay. The health problems associated with radon activity arise from the radioactive products of its disintegration, mentioned above.


    30. The word "disintegration" in the passage is closest in meaning to 

    breakdown
    collapse
    corrosion 
    failure


    Since radon is a gas, it can move from the ground into the air, where it is dispersed by the winds. If it infiltrates buildings, however, it can build up over time and lead to serious health problems. In fact, the radon itself is chemically inert and so does not enter into chemical reactions with other substances. It is readily dissolved in blood and circulates through the body until it is expelled, usually before it has had time to decay. The health problems associated with radon activity arise from the radioactive products of its disintegration, mentioned above.


    31. Health problems associated with radon are caused by 

    radioactive uranium
    certain heavy metals
    decaying gases
    some chemical reactions


    [Refer to the full passage.]


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

    Unlike the radon, which is scattered without danger, its products accumulate as the radon disintegrates.
    Like the radon itself, the decay products are scattered safely and accumulate as the radon decays.
    Like the decaying radon, the progeny are dispersed in accumulations, which can cause harm.
    Unlike the dispersed radon, which accumulates safely, the products of decay are dangerous.


    The products of the decay process, especially polonium-218 and polonium-214, emit radiation, which kills or damages living cells, causing genetic mutations and cancer. These radon progeny are not dispersed harmlessly like radon itself but accumulate as the radon decays. Outside the body, these solid materials can attach themselves to dust particles and surfaces throughout a building and then be inhaled. The decay products can also stick to tobacco leaves during growth and then enter the body when the tobacco is smoked. Inside the body these dangerous by-products of radon become lodged in lung tissue and the bronchial tubes. As these decay, they emit alpha and beta particles and gamma rays. Of these, the alpha particles can do the most damage since they are the bulkiest of the three and therefore cannot penetrate very far into living tissue. Because of this relative immobility. concentrations of the particle form and damage cells in the immediate area. Beta particles and gamma rays are less dangerous since they travel further and are less concentrated in the tissues.


    33. According to paragraph 3, some products of decay cause damage because they 

    emit gamma rays
    cannot penetrate living tissue very deeply
    are highly mobile 
    seep into houses and form concentrations of radiation

    Paragraph 3 is marked with an arrow [->].


    -> The products of the decay process, especially polonium-218 and polonium-214, emit radiation, which kills or damages living cells, causing genetic mutations and cancer. These radon progeny are not dispersed harmlessly like radon itself but accumulate as the radon decays. Outside the body, these solid materials can attach themselves to dust particles and surfaces throughout a building and then be inhaled. The decay products can also stick to tobacco leaves during growth and then enter the body when the tobacco is smoked. Inside the body these dangerous by-products of radon become lodged in lung tissue and the bronchial tubes. As these decay, they emit alpha and beta particles and gamma rays. Of these, the alpha particles can do the most damage since they are the bulkiest of the three and therefore cannot penetrate very far into living tissue. Because of this relative immobility, concentrations of the particle form and damage cells in the immediate area. Beta particles and gamma rays are less dangerous since they travel further and are less concentrated in the tissues.


    34. The phrase "uranium daughter" in the passage refers to 

    water
    radon
    particles
    air


    The primary way that radon penetrates buildings is through foundations. It enters through cracks in basement floors, drains, loose-fitting pipes, and exposed soil areas. Radon also finds its way into water, although if the water is exposed to the atmosphere or agitated, the radon disperses into the air. Because of this, concentrations of this uranium daughter are not high in rivers, but water drawn from underground sources into homes can have elevated levels.


    35. According to the passage, all of the following are true about radon EXCEPT 

    it is invisible
    it cannot be detected
    it cannot be smelled
    it is radioactive


    [Refer to the full passage.]


    36. It can be understood from paragraph 6 that 

    reducing the amount of radon in your home is pointless because of the amount of radon outside
    even though it is possible to test buildings for radon accumulation, it is not possible to minimize the level of radiation activity
    the use of concrete sealing and active ventilation systems can reduce the amount of radon to an acceptable level
    using concrete sealing and installing active ventilation systems reduces the amount of usable living space

    Paragraph 6 is marked with an arrow [->].


    ->It is now possible to have buildings tested for radon accumulation. In an average home, this is about 1.3 picocuries per liter, which is considered an acceptable although not a totally safe level. If these levels are above 4 picocuries per liter of air, then homeowners are advised to reduce the amount seeping into the living space. This can be achieved through various means including concrete sealing and the installation of active ventilation systems. It is not possible to completely eradicate traces of radon since the natural outdoors level averages 0.4 picocuries per liter, but minimizing the amount is a prudent preventative measure.


    37. The word "prudent" in the passage is closest in meaning to 

    sensible
    necessary
    practical
    realistic


    It is now possible to have buildings tested for radon accumulation. In an average home, this is about 1.3 picocuries per liter, which is considered an acceptable although not a totally safe level. If these levels are above 4 picocuries per liter of air, then homeowners are advised to reduce the amount seeping into the living space. This can be achieved through various means including concrete sealing and the installation of active ventilation systems. It is not possible to completely eradicate traces of radon since the natural outdoors level averages 0.4 picocuries per liter, but minimizing the amount is a prudent preventative measure.


    38. Look at the four squares [?] that indicate where the following sentence could be added to the passage. 

    But this research has been criticized for being based on too few subjects.

    Where would the sentence best fit?
    Choose the letter of the square that shows where the sentence should be added.
     A
     B
     C
     D


    The chief health risk from inhaling radon or its daughter products is lung cancer. [A] Scientists have concluded that exposure to this carcinogen is the second leading cause of this disease in the United States. [B] Major scientific organizations believe it contributes to approximately 12 percent of the incidence in the United States alone. It is true that some research has cast doubt on the likelihood of residential radon accumulations contributing to cancer rates.[C] Other larger scale studies contradict the neutral findings. For example, a recent study of 68.000 underground miners who were exposed to high levels of radon shows that they are five times more likely to die of lung cancer than the general population. [D] Smokers, whose incidence of lung cancer is significantly higher than the nonsmoking population, are even more at risk if they are exposed to high levels of radon.



    39. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
    Write the letters of the answer choices in the spaces where they belong. 
    Refer to the full passage.

    Radon can seep into a building, where its decay products can lead to health problems.





    Answer Choices

    A) Although radon can enter a building in many different ways, it also escapes through cracks in the foundations.
    B) Concentrations of the radon by-products attach themselves to particles in the air inside buildings and are breathed into the lungs.
    C) People who smoke or work in mines are at greater risks of getting lung cancer that is related to alpha particles than those who work in buildings.
    D) The by-product alpha particles are too heavy to disperse through the tissues, so they accumulate in the lungs where they kill or damage lung cells.
    E) Radon does not cause lung cancer because it is chemically inert and therefore readily dissolves in the blood, where it eventually is expelled from the body.
    F) Preventative measures can be taken to reduce the amount of exposure to radon in living spaces, but it is not possible to completely eliminate the gas from the atmosphere.

 

 

Answer Keys
DIAGNOSTIC TEST: Reading Section

 

Note: If you answered an item incorrectly, complete

the exercises listed for that item.

1. (B) To "prevail" means "to exist" or "to occur more prominently or notably." See Exercises R1-R3.

2. (D) The phrase "the three most prominent factors" indicates there arc other factors that may not be as prominent. See Exercises R15-R21.

3. (C) The phrase "these eccentricities" refers to the movements of the Earth. The pattern of insolation is not a movement of the Earth. See Exercises R9-R14.

4. (B) The phrase "the match between periods of peak insolation and most intense glaciation were not exact" means that the periods did not occur at the same time. See Exercises R9-R14.

5. (A) The author is using the flat plane image to show the reader how the Earth moves in and out of a plane. See Exercises R15-R21.

6. (D) The Earth, our planet, is plunged into cold periods periodically. See Exercises R4-R8.

7. (D) Space debris reduces the amount of solar energy reaching the Earth. This causes regular cold periods. See Exercises R9-R14.

8. (A) Muller and MacDonald’s theory is supported by the fossil record, whereas Milankovitch's theory is not. See Exercises R9-R14.

9. (A) When someone is "persuaded" or "convinced," they have been shown evidence that makes them believe something. See Exercises R1-R3.

10. (C) The problem with Muller and MacDonald's theory is that the amount of debris that reaches Earth in comparison to the debris from volcanoes appears too small to cool temperatures sufficiently. See Exercises R9-R14.

11. (D)The phrase "Earth is at its furthest from the sun” indicates that this is a detail related to the Earth's orbit around the sun. This would follow the sentence that discusses the elliptical nature of the Earth's orbit. See Exercises R4-R8.

 

12. Flaws in the Milankovitch Cycles Theory

 

(A) Milankovitch's predicted intervals of sunlight do not coincide with the climate records.
(B) The Nevada lake temperature increased before Milankovitch's predicted peaks of sunlight.

(D) Milankovitch's predicted cycles do not always match the periods of most glaciation.

(H) The data from the ocean sediments docs not coincide with Milankovitch's predicted years of glaciation.

 

Flaws in the Muller and McDonald Theory

 

(E) The mild effect of volcanic eruptions on the climate docs not support Muller and MacDonald's theory that interstellar debris affects the amount of sunlight that reaches the Earth.

(G) There is not enough interstellar debris reaching Earth to support Muller and MacDonald's theory that this dust blocks sunlight.

(I) Even though the glaciation corresponds to the periods of the Earth's moving through debris, Muller and MacDonald's theory is not supported by much physical evidence of changes in energy levels. See Exercises R22-R24.

13. (D) The passage mentions that some species are well-adapted to harsh living conditions. It can be understood that such birds don't migrate south. See Exercises R15-R22.

14. (D) The word "those" refers to the species of birds that find moving south in the winter advantageous. See Exercises R4-R8.

15. (D) According to the passage, "changes in the weather can trigger the start of the journey south." See Exercises R9-R14.

16. (A) When fat "accumulates" under the skin, it "builds up." See Exercises R1-R3.

17. (D) The passage does not mention birds migrating east-west toward a hotter climate. Sec Exercises R9-R14.

18. (B) "Precisely" refers to an action that is performed "exactly" without error. See Exercises R1-R3.

19. (C) Since the polarization patterns are visible at sunset and the passage mentions patterns in sunlight, we can infer that they are not visible at night. See Exercises R15-R21.

20. (B) The bowtie shape of the pattern has "fuzzy" ends which are reminiscent of a brush. See Exercises R15-R21.

21. (A) The term "subjected" here means that the birds were exposed to the projection on the inside of the planetarium. See Exercises R1-R3.

22. (C) According to paragraph 6, some research using projections on the planetarium ceiling indicates the birds are guided by the constellations. See Exercises R9-R14.

23. (A) The highlighted sentence means the same as "Birds needing to orientate seemed to use the information... from the stars that rotate around Polaris." See Exercises R9-R14.

24. (В) The word "this" refers to the fact that when fewer stars are visible on the planetarium ceiling, the birds) sense of direction worsened. See Exercises R4-R8.

25. S The particular landscapes such as river valleys and shapes of hills are examples of the topographic features mentioned in the previous sentence. See Exercises R4-R8.

26. (B) (E), and (F) The main ideas from the passage are all theories that scientists have studied in their attempt to understand the methods birds use to migrate. These theories are that birds may determine direction through detection of the gradations of polarization patterns in sunlight, through the rotation of stars around a fixed position, and through knowledge of landscape features. See Exercises R22-R24.

27. (C) The phrase "this element" refers to the parent element, uranium, mentioned in the previous sentence. See Exercises R4-R8.

28. (A) A liquid or gas "seeps" or "leaks" through holes or cracks. Sec Exercises R1-R3.

29. (A) According to paragraph 2, the health problems are caused by radon after it decays into its radioactive particles. If it has not had time to decay, radon is harmless. Sec Exercises R9-R14.

30. (A) When a substance "disintegrates" or "breaks down," it changes from one state into its simpler component parts. See Exercises R1-R3.

31. (B) According to the passage, heavy metals such as polonium, lead, and bismuth, which are products of the decay process of radon, are what cause health problems. See Exercises R9-R14.

32. (A) The гафп progeny are the products that gather together as the radon disperses. See Exercises R9-R14.

33. (B) According to paragraph 3, products of decay, especially alpha particles, arc dangerous because they accumulate into concentrations instead of
dispersing throughout the body. In these concentrations, they damage nearby cells. See Exercises R9-R14.

34. (B) Radon is described as a decay product of uranium and, therefore, is a uranium daughter Exercises R4-R8.

35. (B) It can be understood that radon is detectable because buildings are tested for the amount of radon that has accumulated. See Exercises R9-R34

36. (C) According to paragraph 6, a reduction of radon can be achieved by using concrete sealing and active ventilation systems. See Exercises R15-RI1

37. (A) A "prudent" or "sensible" action is one which wise under the circumstances. See Exercises RI-R-3

38. (c) The phrase "But this research" refers back to the research on radon accumulation and cancer rates See Exercises R4-R8.

39. (B) After radon enters a building, its decay produce form particles that can be breathed into the lungs

    (D) The alpha particles, in particular, accumulate in the lung tissue and damage cells.

    (F) It is possible to reduce radon exposure, but some of the gas stays in the atmosphere.

See Exercises R22-R24.