00382366759Determining the Ages of the Planets and the Universe

The planets of our solar system all revolve around the Sun in the same direction and in orbits that lie in nearly the same plane. This is strong evidence that the planets formed simultaneously from a single disk of material that rotated in the same direction as the modern planets.Precisely when the planets came into being has been a difficult issue to resolve. While Earth's water is necessary for life, its abundance near the planet's surface makes rapid erosion inevitable. Continuous alteration of the crust by erosion and also by igneous (volcanic) and metamorphic (pressure and heat within Earth) processes makes unlikely any discovery of rocks nearly as old as Earth. Thus geologists have had to look beyond this planet in their efforts to date Earth's origin. Fortunately, we do have samples of rock that appear to represent the primitive material of the solar system. These samples are meteorites, which originate as extraterrestrial objects, called meteors, that have been captured in Earth's gravitational field and have then crashed into our planet.Some meteorites consist of rocky material and, accordingly, are called stony meteorites. Others are metallic and have been designated iron meteorites even though they contain lesser amounts of elements other than iron. Still others consist of mixtures of rocky and metallic material and thus are called stony-iron meteorites. Meteors come in all sizes, from small particles to the small planets known as asteroids; no asteroid, however, has struck Earth during recorded human history. Many meteorites appear to be fragments of larger bodies that have undergone collisions and broken into pieces. Iron meteorites are fragments of the interiors of these bodies, comparable to Earth's core, and stony meteorites are from outer portions of these bodies, comparable to Earth's mantle (the layer between the core and outer crust).Meteorites have been radiometrically dated by means of several decay systems, including rubidium-strontium, potassium-argon, and uranium-thorium. The dates thus derived tend to cluster around 4.6 billion years, which suggests that this is the approximate age of the solar system. After many meteorites had been dated, it was gratifying to find that the oldest ages obtained for rocks gathered on the surface of the Moon also were approximately 4.6 billion years. This must, indeed, be the age of the solar system. Ancient rocks can be found on the Moon because the lunar surface, unlike that of Earth, has no water to weather and erode rocks and is characterized by only weak movements of its crust.Determining the age of the universe has been more complicated. Most stars in the universe are clustered into enormous disk-like galaxies. The distance between our galaxy, known as the Milky Way, and all others is increasing. In fact, all galaxies are moving away from one another, evidence that the universe is expanding. It is not the galaxies themselves that are expanding but the space between them. What is happening is analogous to inflating a balloon with small coins attached to its surface. The coins behave like galaxies: although they do not expand, the space between them does. Before the galaxies formed, matter that they contain was concentrated with infinite density at a single point from which it exploded in an event called the big bang. Even after it assembled into galaxies, matter continued to spread in all directions from the site of the big bang.The evidence that the universe is expanding makes it possible to estimate its age. This evidence, called the redshift, is an increase in the wavelengths of light waves traveling through spacea shift toward the red end of the visible spectrum of wavelengths. Expansion of the space between galaxies causes this shift by stretching light waves as they pass through it. The farther these light waves have traveled through space, the greater the redshift they have undergone. For this reason, light waves that reach Earth from distant galaxies have larger redshifts than those from nearby galaxies. Calculations based on these redshifts indicate that about 13.7 billion years ago all of the galaxies would have been at one spot, the site of the big bang. This, then, is the approximate date of the big bang and the age of the universe.

1..According to paragraphs 1 and 2, what evidence leads astronomers to believe that all the planets formed at approximately the same time

Samples of rocks from all the planets are the same age.All the planets orbit the Sun in the same direction and in about the same plane.All planets have the same igneous and metamorphic processes.

00382366759The gravitational field of each planet is about the same strength.

2..The word inevitable in the passage is closest in meaning to

continuousobviouscertaineasy

3..Which of the following is NOT mentioned in paragraph 2 as a cause of constant change to Earth's crust

WaterIgneous processesMetamorphic processesMeteorites

4..The word accordingly in the passage is closest in meaning to

correspondinglyfrequentlyinterestinglyinformally

5..Which of the following can be inferred from paragraph 3 about meteorites

Their composition can help determine the part of the larger body from which they broke off.They are difficult to distinguish from rocks in Earth's mantle.Their collisions with Earth have become more frequent than in the past.They are older than the rest of the solar system.

6..According to paragraph 3, which of the following is a characteristic of asteroids

They are the largest meteors.They are made mostly of iron and other metals.They often collide with Earth.They are the oldest meteors.

7..Which of the following can be inferred from paragraph 4 about the radiometric dating of meteorites

Scientists tried several different radiometric systems before finding one that worked. The radiometric dating of different meteorites produced similar results.Many meteorites were damaged by the radiometric dating.Radiometric dating was not as accurate as scientists expected.

8..The word cluster in the passage is closest in meaning to

approachspreadgroupvary

9..According to paragraph 4, why are scientists confident that the age of the oldest meteorites they studied is also the age of the solar system

00382366759Radiometric dating has been proven to be reliable.The oldest rocks found on the surface of the Moon are the same age as the meteorites.No meteorites have been found that are younger than 4.6 billion years old.Meteorites on the Moon are the same age as those on other planets.

10..The word enormous in the passage is closest in meaning to

expandingvery brightdistanthuge

11..Why does the author refer to inflating a balloon with small coins attached to its surface

To help explain how the universe can expand while the galaxies remain the same sizeTo imply that the universe must eventually stop expandingTo support the statement that most stars are found in disk-shaped galaxiesTo help explain how the universe began as a single point of dense matter

12..According to paragraph 6, how did astronomers learn that the universe is expanding

By measuring the distance between galaxiesBy observing the movement of stars within galaxiesBy studying the wavelengths of light from distant galaxiesBy comparing the sizes of different galaxies

13..Look at the four squares that indicate where the following sentence could be added to the passage.Several varieties of meteorites have been observed. 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.Answer Choices

Determining the age of the planets by examining rocks on Earth is difficult because Earth's crust is constantly changing.All three kinds of meteorites are similar in composition to Earth in that they have an inner core, a rocky mantle, and an outer crust.

Meteorites found on Earth and rocks from the Moon's surface are the best evidence for estimating the age of the planets.Radiometric dating of meteorites recovered from the Moon shows that they are older than those that are found on Earth.

The expansion of the universe makes it possible to estimate its age by measuring the amount of the redshift of light coming from distant galaxies. The redshift phenomenon measures the rate at which the stars in a galaxy are moving away from each other.

The Identification of the Genetic Material

The history of biology is filled with incidents in which research on one specific topic has contributed richly to another, apparently unrelated area. Such a case is the work of Frederick Griffith, an English physician whose attempts to prevent the disease pneumonia led to the identification of the material in cells that contains genetic information the information that determines an organism's

00382366759characteristic structure. In the 1920s, Griffith was studying the bacterium Streptococcus pneumoniae, or pneumococcus, one of the organisms that cause pneumonia in humans. He was trying to develop a vaccine against this devastating illness. He was working with two strains of the bacteria pneumococcus. A bacterial strain is a population of cells descended from a single parent cell; strains differ in one or more inherited characteristics. Griffith's strains were designated S and R because, when grown in the laboratory, one produced shiny, smooth (S) colonies or groups of bacteria, and the other produced colonies that look rough (R).When the S strain was injected into mice, the mice became diseased. When the R strain was injected, the mice did not become diseased. Bacteria of the S strain are virulent (able to cause disease) because they are surrounded by a protective jelly-like coating that prevents the mouse's immune defense mechanisms from destroying the bacteria before they can multiply. The R strain lacks this coating.With the hope of developing a vaccine against pneumonia, Griffith injected some mice with heat-killed S pneumococci. These heat-killed bacteria did not produce infection. Griffith assumed the mice would produce antibodies to the bacteria that would allow them to fight the virulent form if they were exposed to it. However, when Griffith inoculated other mice with a mixture of living R bacteria and heat-killed S bacteria, to his astonishment, the mice became ill with pneumonia. When he examined blood from these mice, he found it full of living bacteriamany with characteristics of the virulent S strain. Griffith concluded that, in the presence of the dead S pneumococci, some of the living R pneumococci had been transformed into virulent S-strain organisms. Did this transformation of the bacteria depend on something the mouse did to the bacteria No. It was shown that simply putting living R and heat-killed S bacteria together in a test tube yielded the same transformation. Next it was discovered that a cell-free extract of heat-killed S cells also transformed R cells. (A cell-free extract contains all the contents of cells, but no intact cells.) This result demonstrated that some substancecalled at the time a chemical transforming principlefrom the extract of S pneumococci could cause a heritable change (a change that could be passed on to future generations) in the affected R cells. From these observations, some scientists concluded that this transforming material carried heritable information, and thus was the genetic material that scientists had been searching for.The identification of the transforming material was a crucial step in the history of biology, accomplished over a period of several years by Oswald Avery and his colleagues at what is now Rockefeller University. They treated samples of the transforming extract in a variety of ways to destroy different types of substancesproteins, nucleic acids, carbohydrates, and lipidsand tested the treated samples to see if they had retained transforming activity. The answer was always the same: If the DNA (deoxyribonucleic acid) in the extract was destroyed, transforming activity was lost; everything else could be eliminated without removing the transforming ability of the extract. As a final step, Avery, with Colin MacLeod and Maclyn McCarty, isolated virtually pure DNA from a sample of pneumococcal transforming extract and showed that it caused bacterial transformation.In retrospect, the work of Avery, MacLeod, and McCarty, published in 1944, was a milestone in establishing that DNA is the genetic material. However, at the time, it had little impact on scientists' view about the physical basis of inheritance. The genetic material had to encode all the information needed to specify an organism, and the chemical complexity and diversity of proteins were known to be impressive. So during the first half of the twentieth century, the hereditary material was generally assumed to be a protein. Nucleic acids, by contrast, were known to have only a few components and seemed too simple to carry such complex information.

1..The word apparently in the passage is closest in meaning to

seeminglysurprisinglyrelativelypreviously

2..According to paragraph 1, Griffith experimented with strains of the pneumococcus bacteria because he wanted to discover which of the following

00382366759

A strain of bacteria that could be used to develop a vaccineHow bacterial strains developed under laboratory conditionsWhy the strains of bacteria differed in appearanceWhich bacterial strains were most infectious in humans

3..Why does the author provide the information that The R strain lacks this coating

To provide an example of variations within strains of pneumococcus bacteriaTo explain why the R strain is not able to cause disease To suggest that the R strain has other ways to defend itself from immune defense mechanismsTo explain why mice became diseased when injected with the R strain

4..The word astonishment in the passage is closest in meaning to

alarmsurprisedisappointmentinterest

5..According to paragraph 3, why did Griffith conclude from his experiment injecting both R and S strains pneumococci into mice that some of the R strain bacteria transformed into disease-causing S strain pneumococci

All the living bacteria he found in the blood of the injected mice were S strain bacteria. He already knew from earlier experiments that R strain pneumococci sometimes transform into S strain pneumococci. He could tell from examining the bacteria under a microscope that some individual pneumococci cells had characteristics of both the S and R strains.He observed living cells in the mice's blood with S strain characteristics, but the only living cells injected were R strain pneumococci.

6..According to paragraph 4, why was Griffith's experiment repeated in a test tube

To provide additional support for the transformation of R-strain into S-strain pneumococci To establish whether or not the transformation of R cells was caused by something the mouse's body didTo determine why the S-strain pneumococci somehow survived if they were in the presence of the R-strain To test the results of adding a cell-free extract to the mixture

7..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.

This result showed that the chemical transforming principle in S pneumococci was passed on to future generations of S pneumococci.After exposure to the cell-free extract from the S pneumococci, R pneumococci strain cells acquired the ability to transform themselves into S pneumococci.The transformation of R cells by a cell-free extract of S pneumococci demonstrated the existence of a chemical transforming principle that brought about heritable change.This transformation showed that the characteristics that the S pneumococci possess are superior to the characteristics of R pneumococci.

8..According to paragraph 5, why did Oswald Avery and his colleagues treat the transforming extract in a variety of destructive ways

00382366759

They hoped to destroy the virulent part of the transforming extract.They wanted to identify the substance responsible for the transforming activity.They wanted to identify which methods would destroy particular substances in the transforming extract.They needed to determine which treatments were most successful in destroying DNA.

9..The word virtually in the passage is closest in meaning to

perfectlynearlypartiallyrelatively

10..The phrase In retrospect in the passage is closest in meaning to

By general agreementIn realityLooking backPractically speaking

11..According to paragraph 6, why did scientists continue to believe that the hereditary material was a protein

Scientists thought that the research of Avery and his colleagues provided insufficient information about the nature of DNA.Scientists believed that only proteins were complex enough to carry genetic information.Scientists thought Avery and his colleagues had little understanding of the physical basis of inheritance.Scientists ignored important milestones that indicated the chemical complexity of DNA.

12..Which of the following can be inferred from the passage about the transformed R-strain pneumococci

They had acquired the genetic information for producing a protective coating.They were unable to cause transformation in other strains of pneumococci. In the presence of heat-killed R-strain bacteria, they lost their virulence.They did not multiply as quickly as nontransformed cells did.

13..Look at the four squares that indicate where the following sentence could be added to the passage.Why 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.Answer Choices

From the 1920s through 1944, researchers used pneumococcus bacteria to discover the properties of DNA because the bacteria was relatively simple, having only two strains.Frederick Griffith discovered that a nonvirulent strain of bacteria could be transformed into a virulent strain by being exposed to dead cells from the virulent strain.

By selectively destroying various substances in the cells of pneumococci bacteria, Oswald Avery and his colleagues identified DNA as the substance that caused bacterial transformation. Oswald Avery injected the combination of heat-killed, virulent cells and nonvirulent cells into mice because he hoped this would lead to a vaccine for pneumonia.

00382366759

Avery and his colleagues were able to isolate Griffith's transforming principle by injecting mice with the extract that contained the transforming principle.Scientists did not initially recognize the importance of the discovery that DNA could cause genetic transformation because the hereditary material was assumed to be a protein.

Tree Species Identification in Tropical Rain Forests

Identifying tree species in tropical rain forests may be harder than you think.Plant species identification can be difficult for all kinds of reasonseven identification of trees, which are big and conspicuous. For example, for some willow trees, both leaves and flowers may be needed for identification, but the two may not be present at the same time. Yet whatever problems may confront us in temperate climates, we can be sure that the tropics will pose far worse difficulties.In tropical rain forests, the flowers of a given tree species are typically not in bloom and so cannot be observed. In seasonal rain forests (with a distinct wet season and a distinct dry season), many trees adjust their flowering to the rains, so flowering is to some extent predictable. But much rain forest (as in much of the Amazon region) is nonseasonal, and trees may flower at any time. To be sure, different trees of the same species generally flower simultaneously, for if they did not, they could not pollinate each other. So they must be responding to signals from the environment at large, or else (or in addition) they must be communicating with one another. But what those signals are is unknown, at least to us. To the human observer, the flowering seems random. In any case, in a tropical forest (at least in a secondary forest, which is forest that is regrowing after previous harvesting or clearance), the trees grow very close together, and most are remarkably thin, like poles, and grow straight up and disappear into the gloom, twenty meters overhead. Even if there are flowers, you would not necessarily see them.The leaves may not be accommodating either, at least when viewed from the ground. Rain-forest trees all face the same kinds of conditions and have adapted in the same general kinds of way. Rain forests are wet by definition. But in some there is a dry season, and even when there is not, it doesn't rain all the time. Thus the forest floor may be moist, but the topmost leaves of the canopy are far above it and are exposed to the fiercest sun. So the uppermost leaves must resist desiccation (drying out). Yet from time to time, and in due season every day, they must also endure tremendous downpours. Leaves that can cope with such contrasts tend to be thick and leathery (to resist drought), oval in shape, and have a projection at the end known as a drip tip to let surplus rain run off the leaf. Many hundreds of trees from dozens of only distantly related families have leaves of this general type. But even if you can distinguish individual leaves, it is hard to be certain if they belong to the tree you are interested in or to the one next to itor to some epiphyte (a plant that grows on other plants) or liana (vine) slung over its branches. Often, in short, researchers must base their identification of a tree on the bark of its trunk. The trunks of tropical trees are sometimes highly characteristic, being deeply furrowed or twisted, but in most species the bark is simply smooth and gray, dappled with lichen and moss.In a temperate forest you can be fairly sure that any one tree is the same species as the one next to itor, at least, it will be one of a list that is unlikely to exceed more than half a dozen (oak with ash in much of Britain; lodgepole pine with aspen in the northernmost reaches of North America; alder, Scotch pine, and spruce in the Baltic; and so on). But in the Amazon in particular, you can be fairly sure that any one tree is not the same species as the one next to it. Often there is a third of a mile between any two trees of the same species, and there can be up to 120 different species of trees in any one acre. So the task, often, is to identify an individual tree that may be not much thicker than your arm from the appearance of its bark, out of a total list of several hundred (or thousand) possibilitieswhich may well include some that have not been described before, so that there is nothing to refer back to.

00382366759

1..The word conspicuous in the passage is closest in meaning to

close to each othercommoneasily noticedsolitary

2..In paragraph 1, why does the author discuss willow trees

To provide an example of a tree that is unusually largeTo explain the process of tree species identificationTo support the idea that tropical trees can be more difficult to identify than temperate treesTo demonstrate one reason why it can be problematic to determine what species a tree belongs to

3..Paragraph 2 implies which of the following about tree flowering in seasonal rainforests

It is less predictable than tree flowering in tropical rain forests.It results from an unknown means of communication between the individual trees of each species.It is more useful to researchers trying to identify tree species than is the tree flowering in tropical rain forests. It follows the same pattern that tree flowering follows in a tropical secondary forest.

4..In paragraph 2, why does the author discuss pollination

To provide evidence that in many tropical tree species flowering is at least somewhat predictableTo help explain why flowers on trees in tropical rainforests can be absent most of the timeTo help explain why different trees of the same species bloom at the same timeTo suggest one reason why trees might benefit from adjusting their flowering to the rains

5..According to paragraph 2, what is true about much of the Amazon region

It has tree species that adjust their pollination to rainfall.It has not yet been harvested or cleared.It has trees that typically flower during periods of rain.It does not have separate wet and dry seasons.

6..The word endure in the passage is closest in meaning to

withstandbenefit fromavoidrespond to

7..The word surplus in the passage is closest in meaning to

heavysteadysuddenextra

8..Paragraph 3 offers an explanation for each of the following characteristics of rain-forest tree leaves EXCEPT

their having a drip-tip at the endtheir thickness

00382366759their leathery texturetheir oval shape

9..According to paragraph 3, what is one reason that looking at leaves may not be very useful when trying to determine the species of a rain-forest tree

Leaves of rainforest trees often look very different when they are wet than when they are dry.Leaves that are exposed to the hot tropical sun dry out and lose their distinguishing characteristics.It can be hard to determine whether a leaf has a drip tip or not.It can be hard to determine whether a leaf belongs to a tree or to another plant growing on the tree.

10..According to paragraph 3, one reason that researchers in tropical forests must often rely on a tree's bark for species identification is that

distinct species of tree often have similar kinds of lichens and moss growing on their trunksthe leaves of many different tropical tree species are very similar to each other in appearancemany rainforest trees have neither epiphytes nor lianasthe bark of the trees is less affected by changes in light and moisture than leaves are

11..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.

Different temperate forests contain different combinations of tree speciesbut in all such forests, all the trees of any one species are likely to be found close together.Temperate forests rarely contain more than about six species of tree, and trees growing next to each other tend to be of the same species.You can easily make a list of all the tree species that are likely to be found in temperate forests, and if one tree is not on that list, you can be confident that the tree next to it will be.Forests in Britain, in North America, and in the Baltic generally contain no more than half a dozen tree species, and all these species can be found on lists.

12..The word task in the passage is closest in meaning to

difficultyjobstrategyrequirement

13.. Look at the four squares that indicate where the following sentence could be added to the passage. As a result, the topmost level of a rainforest can be desert-like. 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 . Answer Choices

In tropical forests different trees of the same species flower at different times so they are not able to pollinate one another.Flowering in tropical trees is often unpredictable and when it occurs, the flowers themselves tend to be too high up to be clearly visible.

Many tropical tree species have leaves that look very similar from the ground, and because the trees often grow close together, correctly matching a leaf with a particular tree can be difficult.

00382366759The leaves and bark of a single rainforest tree are often very different at different heights due to the need to adapt to different conditions, which adds to the difficulty of species identification.

Because trees in rain forests are spaced closely together, it is easy to tell whether neighboring plants are the same species, but that is not much help in determining which species they are. Often, a rain-forest tree has to be identified by its bark, but trees of like species are widely scattered, the list of possible species is very long, and many have similar-looking bark.

The Extinction of the Dinosaurs

Geologists define the boundary between sediment layers of the Cretaceous period (144C65 million years ago) and the Paleocene period (65C55 million years ago) in part by the types and amounts of rocks and fossils they contain or lack. Before the limit of 65 million years ago, marine strata are rich in calcium carbonate due to accumulations of fossils of microscopic algae deposited on the sea floor. Above the 65-million-year limit, sea-floor sediments contain much less calcium carbonate, and fossils of several families of mollusks are no longer found. In continental sediments, dinosaur fossils, though frequent before 65 million years ago, are totally absent. By contrast, new families of mammals appear, including large mammals for the first time.Scientists wondered for many years about what could have caused the dinosaurs' rapid disappearance at the end of the Cretaceous period, coming up with a great variety of theories and scenarios. For some, it could have been due to unfavorable genetic changes triggered by a dramatic increaseby a factor of 10, 100, 1,000 in cosmic-ray particles reaching the Earth after a supernova explosion somewhere in the neighborhood of the solar system. For these high-energy particles to affect life, they would have to get through the protective barrier of the Earth's magnetosphere, the region of the upper atmosphere controlled by Earth's magnetic field. That could have happened if the cloud of particles from the supernova explosion reached the Earth during a period when the magnetosphere was weakened, something that may happen when the Earth's magnetic field changes direction. And we know that the magnetic north and south poles of the Earth switch on the average twice every million years. However, this is not the only possible explanation for dinosaur destruction.Other theories have raised the possibility of strong climate changes in the tropics (but they then must be explained). Certainly, if climate changes, the changed distributions of temperature and rainfall modify the conditions that favor one ecosystem over another. The extinction of a particular family, genus, or species may result from a complicated chain of indirect causes and effects. Over thirty years ago, scientist Carl Sagan quoted one suggestion that the demise of the dinosaurs resulted from the disappearance of a species of fern plant that was important for dinosaur digestion. Other theories involved a worldwide cold wave following the spread of a layer of cold but not very salty water in the world's oceans, which floated on the surface because, with its low salinity, the water was less dense.Proponents of another theory that remains under consideration today postulate that the extinction of the dinosaurs corresponds to a period of intense volcanic activity. It's not a question of just one or even of a thousand eruptions comparable to the explosion of Krakatoa in 1883, one of the largest volcanic events in modern times, but rather of a prolonged period of activity. On the Deccan plateau in India, basalt (volcanic) rocks cover more than 500,000 square kilometers (nearly 200,000 square miles), and correspond to massive lava outflows occurring precisely at the end of the Cretaceous. This sort of outflow could correspond to volcanic activity similar to the activity that drives sea-floor spreading, with lava emerging from elongated fractures in the crust rather than from craters.The volcanic convulsion that buried the Deccan plateau in lava must also have changed the composition of the atmosphere and severely affected climate. Initially, there must have been strong

00382366759sudden cooling resulting from the blocking of sunlight by sulfate aerosol veils in the stratosphere (part of the Earth's atmosphere). If strong cooling lasted a year after the formation of the aerosols, it would have been the death of tropical species unable to adapt to such a volcanic winter. However, a long period of strong volcanic activity (again, remember thousands of Krakatoas) would at the same time have added a substantial amount of carbon dioxide to the atmosphere, reinforcing the greenhouse effect. This would gradually warm things up, ending the extended cold snap and producing global warming together with geographic shifts of humid and arid (dry) zones. Certainly things would change to upset living conditions, leading to the extinction of some species while others would profit, if only from the disappearance of predators.

1..According to paragraph 1, which of the following is true of Paleocene sediments

They lack fossils from some families of mammals found in Cretaceous sediments.They contain fossils of dinosaurs.They contain fossils of some animals that did not exist during the Cretaceous.They contain fossils of more kinds of mollusks than are found in Cretaceous sediments.

2..The word unfavorable in the passage is closest in meaning to

unusualdisadvantageoussuddenmajor

3..The word triggered in the passage is closest in meaning to

initiatedintensifiedfollowedaided

4..Why does the author include the information that the magnetic north and south poles of the Earth switch on the average twice every million years

To provide evidence showing that Earth's protective barrier is difficult to get throughTo show that it is reasonable to think that particles from a supernova explosion could have reached EarthTo explain why some scientists believe a supernova explosion may have occurred near our solar systemTo help explain why some scientists have rejected the theory presented in paragraph 2

5..According to the theory discussed in paragraph 2, a weakening of Earth's magnetosphere may have

caused a supernova to explode near our solar systemallowed gene-altering particles to reach Earth's surfaceforced Earth's magnetic field to change directionallowed clouds of protective particles to escape from Earth's upper atmosphere

6..All of the following are mentioned in paragraph 3 as possible causes for the extinction of the dinosaurs EXCEPT

a change in the diet of dinosaursa change in the climate of the tropics

00382366759a decrease in global temperaturesa decrease in deep ocean salinity

7..In paragraph 3, why does the author include the quotation by Carl Sagan

To explain the connection between dinosaur extinction and the extinction of other animal speciesTo support the claim about species extinction being due to indirect causes and effectsTo show that scientists have revised their ideas greatly in the last thirty yearsTo identify the differences between the various theories for the extinction of dinosaurs

8..According to paragraph 4, what was one unusual aspect of the volcanic activity at the end of the Cretaceous

Some explosions were much larger than Krakatoa.Eruptions occurred over a long period of time.Active volcanoes were sometimes separated by many kilometers.There were active volcanoes in the sea as well as on land.

9..Which of the following is presented in paragraph 4 as evidence that intense volcanic activity occurred at about the time that the dinosaurs became extinct

The size of the volcanic craters on the Deccan plateauAn increase in sea-floor spreadingThe formation in India of large amounts of a type of rock associated with volcanoesThe occurrence of a thousand or more volcanic explosions the size of Krakatoa

10..The word severely in the passage is closest in meaning to

certainlyconsequentlygreatlypermanently

11..The word reinforcing in the passage is closest in meaning to

making possiblespreadingintroducingstrengthening

12..According to paragraph 5, all of the following are theorized to have occurred as a result of volcanic activity EXCEPT

a decrease in the amount of sunlight reaching Earth's surfacea reduction in the number of sulfate aerosol veils in the stratosphereincreased dryness in some areas that were once more humidchanges in the atmosphere's composition resulting in an increase in temperature

13.. Look at the four squares that indicate where the following sentence could be added to the passage. Thus, ecosystems following periods of extensive volcanic activity necessarily had different combinations of species than earlier ecosystems did. 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 .

00382366759Answer Choices

Cosmic rays from a nearby supernova explosion may have penetrated Earth's atmosphere, causing genetic changes that dinosaur populations could not survive.Climate changes in the tropics may have set off a chain of indirect effects that negatively affected the ecosystems in which dinosaurs lived.

The spread of lava over large parts of previously favored habitats such as the Deccan Plateau may have made these favored areas uninhabitable for many years.Although the volcanic winter resulting from the formation of sulfate aerosols eventually ended, temperatures may have remained below levels required by dinosaurs to survive.

Temperature changes and geographic shifts in climate zones due to the atmospheric effects of volcanic activity may have been significant enough to cause extinction.To be convincing, theories about what caused dinosaurs to become extinct must be able to explain the disappearance of other predators in the food chain at the same time

1..Why does the man go to see the professor

To discuss the results of a survey he has distributed To ask for advice on how to collect dataTo ask for an explanation of a research project the class studiedTo ask for more time to complete his research project

2..What is the topic of the man's survey

A proposal to build a new highway on the edge of townPlans to change the house numbers along Route 62Plans to build more houses next to Route 62A proposal to make Route 62 wider

3..Why does the professor mention cake

To illustrate the importance of finding a representative sampleTo illustrate why the man will need only a small sampleTo explain why some areas of town are more crowded than othersTo explain the disadvantage of relying only on questionnaires

4..What does the professor suggest the man do

Speak to as many people who live near Route 62 as possibleFind some samples of surveys at the libraryGet information from the telephone company to decide whom to callPass out questionnaires that people will return by mail

5..What does the professor mean when she says this:

The man should not change his plan.The man has little time to finish the project.The man should have spoken with her earlier.

00382366759The man needs more experience at writing traditional papers.

6..What is the lecture mainly about

Unusual features of melting glaciersEffects of ocean currents on glacier meltingAn unconventional research methodAn environmental problem caused by large ships

7..Why does the professor mention an incident involving a cargo ship in the Pacific Ocean

To point out the main weakness of flotsam scienceTo explain the origins of flotsam scienceTo emphasize the ongoing need for flotsam scienceTo provide an example of how flotsam science benefits industry

8..According to the professor, what were scientists able to identify in Pacific Ocean currents as a result of flotsam science

Long-term changes in temperature and salt contentFluctuations in the growth of algaeThe relationship between ocean depth and water movementHow winds affect water speed and direction

9..Why does the professor mention organisms that thrive in the upper portions of the ocean

To contrast glacial meltwater with ocean waterTo discuss a limitation of a certain type of scientific deviceTo indicate a new research area to which flotsam science can contributeTo provide an example of how ocean currents affect water temperatures

10..According to the professor, why has one scientist used toy ducks to study moulins

Click on 2 answers.

They can withstand cold temperatures and high pressure.They do not harm the environment.They can be easily equipped with electronic measuring devices.They are very inexpensive.

11..Why does the professor say this:

To indicate the researcher's thought processTo express surprise at the outcome of an experimentTo admit to not knowing how to answer the researcher's questionTo question a flawed assumption made by the researcher

12..What is the main focus of the lecture

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How the economic worth of trees in urban settings is determinedHow urban planners determine which trees are the most beneficial to citiesWhy some cities do not plant many treesWhere trees can make the greatest economic impact in urban areas

13..What does the professor imply about the practice of assigning a monetary value to trees

It has motivated residents in some cities to plant a large number of trees.It has not yet been shown to have a positive economic impact on cities.It is motivated by the need to make decisions about spending money on planting or maintaining trees.It is a practice that involves too many factors for the result to be meaningful.

14..What does the professor say about the sales comparison approach

Its results depend on the appraisers involved.Appraisers do not like it.Few cities use this approach.It is an outdated approach.

15..A student mentions that trees can save energy by providing shade. What other benefits does the professor mention that can be accounted for in the benefit-based approach

Click on 2 answers.

Reducing the amount of pollution in the airHelping to decrease floodingMaking streets more attractive for retailersReducing the costs of repairing pavement

16..Why does the man talk about the length of time it takes for a tree to grow

To explain why he thinks that tree maintenance is important to the benefit-based approachTo suggest why the sales comparison approach is preferable to the benefit-based approach To raise a question about the accuracy of the benefit-based approach in determining the monetary value of trees To explain why foresight is needed to create an urban forest

17..What does the professor say about the social benefits of trees

They are less important than other benefits.They can be difficult to quantify.They have only recently been acknowledged by city planners.They are more obvious to most people than are other benefits of trees.

1..What is the conversation mainly about

00382366759Effective techniques for photographing architectureA project to document ongoing construction projects on campusImages needed to update a university publicationWhy the man prefers to use student photographers rather than a professional

2..What is the man's attitude toward the woman's photographs

Click on 2 answers.

He is surprised that they were not taken more recently.He is disappointed because they show only the exterior of buildings.He is curious about the type of lens she used to take them.He is impressed by their professional quality.

3..Why is the woman interested in photographing buildings on campus

To fulfill a graduation requirementTo increase her chances of finding employmentTo earn extra credit in her architectural photography courseTo practice using her new camera lens

4..What does the man imply about the guidebook

It is sold at a discount to prospective students.It took two years to design.It is used to help recruit students to the university.It includes photographs of student activities only.

5..What does the man say about the deadline

It is not realistic.It applies to professional photographers only.It was set by a university committee.It can be extended for the woman.

6..What is the lecture mainly about

Click on 2 answers.

Hassam's influence on artists who immigrated to the United StatesAn aspect of Hassam's body of work that distinguished him from other Impressionist painters in the United StatesA critical period in Hassam's rise to prominence as an Impressionist painterRelationships between the elements in some of Hassam's paintings

7..What does the professor imply when he discusses the Industrial Age

Many European Impressionists immigrated to the United States during this era.Growing populations in cities led to an increased consumer demand for artworks.U.S. Impressionists wanted their paintings to offer relief from certain aspects of city life.

00382366759Many U.S. Impressionists permanently moved to the countryside when the cities got overcrowded.

8..What is the professor's attitude regarding the paintings that Hassam made on Appledore Island

He thinks they are more interesting than Hassam's New York City paintings.He is surprised that they do not include more people.He is impressed by how many of them there are.He doubts that they were actually painted outside.

9..According to the professor, how does Hassam unite the images in his painting The Breakfast Room,Winter Morning

Click on 2 answers.

By placing them to suggest the presence of a geometric shapeBy reflecting sunlight off of interior spacesBy including natural objects from the outdoors in an indoor settingBy strategically repeating the use of certain colors

10..According to the professor, what idea does Hassam suggest by obscuring the Flatiron Building behind a curtain in The Breakfast Room,Winter Morning

The need to control the extent to which modernity invades people's livesThe mysterious forces driving New York City's growth The challenge of earning a living in a big cityThe difficulty of maintaining a sense of permanence in a changing world

11..What does the professor mean when he says this:

The midwestern United States was not visually interesting to most Impressionist painters.The effect of sunlight on painters' subjects varies significantly from place to place. Hassam was strongly influenced by his environment when he painted The Breakfast Room.Hassam relied on feedback from other New York City artists to improve his work.

12..What are the speakers mainly discussing

Animal behavior that cannot be explained by natural selectionThe evolution of various forms of deceptive animal communicationPossible reasons that animals communicate truthful messagesResearch that shows similarities between human and animal signals

13..What point does the professor make about human communication

It is often influenced by social rules.It almost always consists of truthful messages.It does not always rely on spoken language.It breaks down when someone exaggerates.

14..Why does the professor talk about lions

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To compare two ways that lions communicate with each otherTo introduce the concept of signal reliability in the animal kingdomTo point out why lions often win fights against animals of other speciesTo explain some of the benefits of exaggerating one's own strength

15..The speakers discuss a hypothetical scenario involving bears. In this scenario, what would happen to the first bears that used deceptive signals

They would reproduce more than other animals in their species.They would not have energy for tasks other than communication.They would become unable to understand signals from other animals.They would eventually return to using only honest signals.

16..What does the professor imply when she talks about the handicap principle

Weak animals defend themselves by increasing the volume of their vocalizations.Most animals' vocalization behavior is not explained by the handicap principle. Some animal species cannot afford the costs of honest communication.Individual animals' behavior is consistent with long-term benefit to the species.

17..Why does the professor say this:

To encourage the students to contribute some of their ideasTo express surprise that some animal communication has broken downTo emphasize that the situation she describes would be unfavorableTo suggest that honest communication can sometimes lead to chaos

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1..Your university plans to offer students cash awards for high performance in one of the following activities: Volunteer service Athletic achievement Academic performanceChoose ONE and explain why you think it deserves to be rewarded. Use examples and details in your response.

2..Some universities require all students to study a foreign language in order to graduate. Other universities require all students to take computer classes before graduating. Which do you think is most important Why

3..Reading Time: 50 secondsEnergy-Saving Challenge

Next month a contest will be held among all of the campus residence halls to determine which dormitory can use the least amount of electricity. The university will monitor power usage in all dormitories, and the students of the dormitory that uses the least electricity in the month will be announced as the winners. One goal of the contest is to increase students' awareness of energy use, and it is hoped that this will lead to a decrease in electricity consumption. In the following month, students in the winning dormitory will be awarded a pizza party catered by a popular local restaurant.

The woman expresses her opinion about the plan described in the article. Briefly summarize the plan. Then state her opinion about the plan and explain the reasons she gives for holding that opinion.

4..Reading Time: 50 secondsRestraint Bias

00382366759People are often challenged by temptations or desires, and at times, these temptations may prevent a person from reaching certain goals. Resisting temptation can be difficult. In fact, psychologists have found that people often overestimate their own ability to resist temptation. This tendency is known as restraint bias. Restraint bias makes people feel as if they have more power to control, or restrain, their behavior than they actually do. So instead of being cautious about tempting situations and avoiding them, people put themselves in such situations. They believe they will be able to control their actions, but in reality they often do not.

Explain how the example from the lecture illustrates the concept of restraint bias.

5..

Briefly summarize the problem the speakers are discussing. Then state which of the two solutions from the conversation you would recommend. Explain the reasons for your recommendation.

6..

Using points and examples from the lecture, explain two ways animals use ultraviolet light.

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1..Bats play a crucial role in the ecosystem of North America: a bat can eat hundreds of insects in a night, reducing the need for harmful pesticides. Unfortunately, a mysterious sickness called white nose syndrome has killed over five million North American bats in the past few years, and it could wipe out several species of bats in the next few decades. The name comes from a white fungus found on infected bats; scientists think that this fungus causes bats to interrupt their normal winter sleep. Bats that wake up cannot find food and die of starvation. Several suggestions have been made to fight white nose syndrome.First, people should stay away from the caves where bats sleep in the winter. The fungus is harmless to humans but can easily be carried on clothes or shoes from one cave to another. Many of the caves where bats have been infected are popular tourist spots for humans, and many scientists believe that the fungus likely spreads from cave to cave by riding on people's clothes.Second, we need to focus on researching a species of bat that lives in Europe that appears to be able to fight the fungus. Bats of that species have been able to stay healthy even after coming in contact with the fungus, suggesting that they have evolved resistance to the fungal infection. By studying how the European bats resist the fungus, we can learn how to help American bats.Finally, some researchers have suggested heating the caves with the largest bat populations. The fungus that causes white nose syndrome is known to grow only at temperatures around 4C. This is the temperature of most bat caves, but if we could raise that temperature just a little bit during the winter, the fungus would not be able to spread and infect the bats.

Directions: You have 20 minutes to plan and write your response. Your response will be judged on the basis of the quality of your writing and on how well your response presents the points in the lecture and their relationship to the reading passage. Typically, an effective response will be 150 to 225 words.

Question: Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific suggestions made in the reading passage.

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2..Directions: Read the question below. You have 30 minutes to plan, write, and revise your essay. Typically, an effective response will contain a minimum of 300 words.

Question:Do you agree or disagree with the following statement The more money a person has, the more he should give to charities (for example, organisations that help people in need).Use specific reasons and examples to support your answer.