PSAT Critical Reading : Content of Natural Science Passages

Study concepts, example questions & explanations for PSAT Critical Reading

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Example Questions

Example Question #5 : Drawing Conclusions In Science Passages

"Interpreting the Copernican Revolution" by Matthew Minerd (2014)

The expressions of one discipline can often alter the way that other subjects understand themselves. Among such cases are numbered the investigations of Nicolaus Copernicus. Copernicus is best known for his views concerning heliocentrism, a view which eventually obliterated many aspects of the ancient/medieval worldview, at least from the standpoint of physical science. It had always been the natural view of mankind that the earth stood at the center of the universe, a fixed point in reference to the rest of the visible bodies. The sun, stars, and planets all rotated around the earth.

With time, this viewpoint became one of the major reference points for modern life. It provided a provocative image that was used—and often abused—by many people for various purposes. For those who wished to weaken the control of religion on mankind, it was said that the heliocentric outlook proved man’s insignificance. In contrast with earlier geocentrism, heliocentrism was said to show that man is not the center of the universe. He is merely one small being in the midst of a large cosmos. However, others wished to use the “Copernican Revolution” in a very different manner. These thinkers wanted to show that there was another “recentering” that had to happen. Once upon a time, we talked about the world. Now, however, it was necessary to talk of man as the central reference point. Just as the solar system was “centered” on the sun, so too should the sciences be centered on the human person.

However, both of these approaches are fraught with problems. Those who wished to undermine the religious mindset rather misunderstood the former outlook on the solar system. The earlier geocentric mindset did not believe that the earth was the most important body in the heavens. Instead, many ancient and medieval thinkers believed that the highest “sphere” above the earth was the most important being in the physical universe. Likewise, the so-called “Copernican Revolution” in physics was different from the one applied to the human person. Copernicus’ revolution showed that the human point of view was not the center, whereas the later forms of “Copernican revolution” wished to show just the opposite.

Of course, there are many complexities in the history of such important changes in scientific outlook. Nevertheless, it is fascinating to see the wide-reaching effects of such discoveries, even when they have numerous, ambiguous effects.

Which of the following would likely be most interesting to those who believe the underlined sentence?

Possible Answers:

None of the other answers

Human culture

The chemical basis for human emotions

Evolution of primates into man

Human anatomy

Correct answer:

Human culture

Explanation:

The group noted in the underlined sentence has an interest in the human person precisely taken as a human person. That is, they are interested in the unique characteristics of human life. All of the incorrect answers consider something that is not necessarily unique to human life (though they do involve human beings). The other subjects are more like applications of chemistry and biology to the human person. However, human culture is unique to the human person. Therefore, it would most likely interest these people quite a bit.

Example Question #21 : Making Inferences About The Author Or Natural Science Passage Content

"The Place of Lesion Studies in Neuroscience" by Samantha Winter (2013)

It’s easy to forget that the study of neuroscience originated from non-normalized, non-statistically appraised methods like lesion studies. It’s equally easy, with the advent of sophisticated technology, to render such a method obsolete. A small group of neuroscientists today make a case for the reinstitution of lesion studies—the study of abnormal brains with damaged regions in order to better understand the brain—into the twenty-first-century cognitive neuroscience realm. Their suggestion is bold, but their argument is justified.

Cognitive neuroscientists advocate for the use of convergent methods. Many of them argue that with the limitations of our existing techniques, convergent evidence is imperative for sound research. If this is the case, why ignore a method that has potential for implying causality in a domain dominated by correlational research? Rather than advocating for a single method, neuroscientists should take their own advice and use convergent techniques. Sound research should combine a variety of techniques to examine both causal relationships and overcome the individual shortcomings of each method through the use of many.

Lesion studies are also significantly more beneficial now than they were in earlier times. Neuroimaging methods have enhanced our understanding of what contributes to the brain problems most often encountered, and more refined experiments have been developed to confirm the findings from the more unreliable lesion studies. This transformation allows lesion studies to be included alongside the other systems as a mechanism for understanding the human brain.

The author would most likely agree with which of the following statements?

Possible Answers:

It is important to eliminate old methods and techniques to avoid being archaic in all fields.

The study of abnormality should be the primary focus of all research.

Neuroscience is the most important branch of science.

The best research uses a number of techniques to understand a concept.

Scientific research should receive more financial support.

Correct answer:

The best research uses a number of techniques to understand a concept.

Explanation:

The main argument of this passage is that numerous techniques should serve to compliment each other and produce the best results. Presumably, the author’s opinion in neuroscience would likely apply to research overall. The author argues against "it is important to eliminate old methods and techniques to avoid being archaic in all fields hh. Scientific research should receive more financial support." There is no indication that financial support has any contribution to the author’s argument, therefore "scientific research should receive more financial support" is incorrect. Finally, "the study of abnormality should be the primary focus of all research" is incorrect because the support of lesion studies in this passage is not derived from a desire to study abnormality, but to understand regular functioning using a method that assesses abnormal functioning.

Example Question #242 : Sat Critical Reading

"The Cell Cycle" by Joseph Ritchie (2014)

The process by which cells divide and multiply is known as the cell cycle. This cycle consists of two main phases: interphase and mitosis. Each phase consists of a series of clearly defined and observable steps. At the conclusion of the cycle, each parent cell produces two genetically identical daughter cells that may also replicate by proceeding through the cell cycle.

Roughly ninety percent of the cell cycle is spent in interphase. Interphase is comprised of three main steps: the first gap phase, the synthesis phase (also called "S phase"), and the second gap phase. The initial gap phase is a period of cellular preparation in which the cell increases in size and readies itself for DNA synthesis. In the synthesis phase, or S phase, DNA replication occurs, so that when the cell divides, each daughter cell will have the DNA necessary to function properly. In the second gap phase, the cell grows in size and prepares for cellular division in the mitotic phase. At the end of each gap phase, the cell has to pass a regulatory checkpoint to ensure that nothing is going wrong. If anything has gone wrong, the checkpoints stop the cell from proceeding through the cell cycle any further.

The next part of the cell cycle is mitosis. Mitosis is a form of cell division and is broken down into five distinct phases. During prophase, the genetic material contained in the cell’s chromatin condenses into distinct chromosomes. Prometaphase is marked by the breakdown of the cell’s nuclear envelope and the formation of centrosomes at the poles of the cell. During metaphase, the cell’s chromosomes are moved to the center of the cell. A checkpoint ensures that the chromosomes are properly aligned on the center and halts the cell cycle if any errors have occurred. In anaphase, chromosomes break apart at their center, or centromere, and sister chromatids move to opposite ends of the cell. Lastly, telophase and cytokinesis occur as nuclear membranes form to physically divide the cell into two new daughter cells. Chromosomes also unwind into loose chromatin during this part of mitosis. Cytokinesis is defined as the division of the each cell’s cytoplasm and organelles. At the conclusion of the cell cycle, two genetically identical daughter cells have formed.

The cell cycle operates by a series of checkpoints and external cues. This system of checks enables the cell to enter a state of dormancy known as the gap zero phase when conditions or other factors inhibit the cell cycle. Conversely, unregulated and uncontrolled cellular division can occur under certain circumstances. A cell in a state of uncontrolled division is known to be cancerous. Lastly, cells have the ability to mediate their own death by way of apoptosis if certain genetic or physical abnormalities exist. The cell cycle is a complex process that enables cells to replicate and proliferate under a stringent set of checks and balances that produce healthy and viable daughter cells that are each able to perform the process in the future.

About how much time does a cell spend undergoing mitosis in the cell cycle?

Possible Answers:

Fifteen percent

Fifty percent

Ten percent

Twenty-five percent

Correct answer:

Ten percent

Explanation:

At the beginning of the second paragraph, the passage says, "Roughly ninety percent of the cell cycle is spent in interphase." Based on this information, and the fact that we are told that the cell cycle consists of "two main phases: interphase and mitosis," we can thus infer that about ten percent of a cell's time in the cell cycle is spent undergoing mitosis.

Example Question #31 : Drawing Inferences From Natural Science Passages

Adapted from Volume Four of The Natural History of Animals: The Animal Life of the World in Its Various Aspects and Relations by James Richard Ainsworth Davis (1903)

The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort of surrounding. There are, however, numerous animals which possess the power of adjusting their color more or less rapidly so as to harmonize with a changing environment.

Some of the best known of these cases are found among those mammals and birds that inhabit countries more or less covered with snow during a part of the year. A good instance is afforded by the Irish or variable hare, which is chiefly found in Ireland and Scotland. In summer, this looks very much like an ordinary hare, though rather grayer in tint and smaller in size, but in winter it becomes white with the exception of the black tips to the ears. Investigations that have been made on the closely allied American hare seem to show that the phenomenon is due to the growth of new hairs of white hue. 

The common stoat is subject to similar color change in the northern parts of its range. In summer it is of a bright reddish brown color with the exception of the under parts, which are yellowish white, and the end of the tail, which is black. But in winter, the entire coat, save only the tip of the tail, becomes white, and in that condition the animal is known as an ermine. A similar example is afforded by the weasel. The seasonal change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.

What can we infer preceded this paragraph?

Possible Answers:

Descriptions of changing environments

Descriptions of animals that have not adapted to their environments

Descriptions of animals that defend themselves by looking like things in a stable environment

Descriptions of animals that defend themselves by looking like things in a changing environment

Descriptions of animals that hunt other animals efficiently by camouflaging themselves

Correct answer:

Descriptions of animals that defend themselves by looking like things in a stable environment

Explanation:

In order to infer what likely “preceded,” or came before, this passage, we should take at what the passage is talking about right when it starts. The passage’s first sentence says, “The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort of surrounding.” The “so far quoted” means so far said or provided and tells us that the writer has been talking about “examples of protective resemblance.” This means that the writer most likely discussed “animals that defend themselves by looking like things in a stable environment” in the part of the book that comes right before the passage.

Example Question #223 : Isee Upper Level (Grades 9 12) Reading Comprehension

Adapted from Volume Four of The Natural History of Animals: The Animal Life of the World in Its Various Aspects and Relations by James Richard Ainsworth Davis (1903)

The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort of surrounding. There are, however, numerous animals which possess the power of adjusting their color more or less rapidly so as to harmonize with a changing environment.

Some of the best known of these cases are found among those mammals and birds that inhabit countries more or less covered with snow during a part of the year. A good instance is afforded by the Irish or variable hare, which is chiefly found in Ireland and Scotland. In summer, this looks very much like an ordinary hare, though rather grayer in tint and smaller in size, but in winter it becomes white with the exception of the black tips to the ears. Investigations that have been made on the closely allied American hare seem to show that the phenomenon is due to the growth of new hairs of white hue. 

The common stoat is subject to similar color change in the northern parts of its range. In summer it is of a bright reddish brown color with the exception of the under parts, which are yellowish white, and the end of the tail, which is black. But in winter, the entire coat, save only the tip of the tail, becomes white, and in that condition the animal is known as an ermine. A similar example is afforded by the weasel. The seasonal change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.

Based on the passage, what can we infer about the weasel?

Possible Answers:

Like the Irish hare, has been the subject of investigations.

Like the Irish hare, it has grey fur in the summer.

Like the stoat, it also lives in burrows.

Like the stoat, it also changes its coat color.

Like the stoat, it has claws.

Correct answer:

Like the stoat, it also changes its coat color.

Explanation:

The weasel is mentioned in two places in the passage, both in the passage’s last paragraph, both reproduced here:

“But in winter, the entire coat [of the stoat], save only the tip of the tail, becomes white, and in that condition the animal is known as an ermine. A similar example is afforded by the
weasel. The seasonal change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.”

What does the passage tell us about the weasel? Well, we can infer that it is in some way like the stoat, because the passage says “A similar example is afforded by the weasel” right after describing how the stoat’s fur changes color. We are also told that it is carnivorous, but this is not an inference we have to make, and it doesn’t relate to any of the answer choices. The best answer choice is “Like the stoat, it also changes its coat color.” This captures the specific similarity between the stoat and weasel being discussed when the author writes, “A similar example is afforded by the weasel.”

Example Question #13 : Making Inferences And Predictions In Science Passages

Adapted from “Feathers of Sea Birds and Wild Fowl for Bedding” from The Utility of Birds by Edward Forbush (ed. 1922)

In the colder countries of the world, the feathers and down of waterfowl have been in great demand for centuries as filling for beds and pillows. Such feathers are perfect non-conductors of heat, and beds, pillows, or coverlets filled with them represent the acme of comfort and durability. The early settlers of New England saved for such purposes the feathers and down from the thousands of wild-fowl which they killed, but as the population increased in numbers, the quantity thus furnished was insufficient, and the people sought a larger supply in the vast colonies of ducks and geese along the Labrador coast. 

The manner in which the feathers and down were obtained, unlike the method practiced in Iceland, did not tend to conserve and protect the source of supply. In Iceland, the people have continued to receive for many years a considerable income by collecting eider down, but there they do not “kill the goose that lays the golden eggs.” Ducks line their nests with down plucked from their own breasts and that of the eider is particularly valuable for bedding. In Iceland, these birds are so carefully protected that they have become as tame and unsuspicious as domestic fowls In North America. Where they are constantly hunted they often conceal their nests in the midst of weeds or bushes, but in Iceland, they make their nests and deposit their eggs in holes dug for them in the sod. A supply of the ducks is maintained so that the people derive from them an annual income.

In North America, quite a different policy was pursued. The demand for feathers became so great in the New England colonies about the middle of the eighteenth century that vessels were fitted out there for the coast of Labrador for the express purpose of securing the feathers and down of wild fowl. Eider down having become valuable and these ducks being in the habit of congregating by thousands on barren islands of the Labrador coast, the birds became the victims of the ships’ crews. As the ducks molt all their primary feathers at once in July or August and are then quite incapable of flight and the young birds are unable to fly until well grown, the hunters were able to surround the helpless birds, drive them together, and kill them with clubs. Otis says that millions of wildfowl were thus destroyed and that in a few years their haunts were so broken up by this wholesale slaughter and their numbers were so diminished that feather voyages became unprofitable and were given up. 

This practice, followed by the almost continual egging, clubbing, shooting, etc. by Labrador fishermen, may have been a chief factor in the extinction of the Labrador duck, that species of supposed restricted breeding range. No doubt had the eider duck been restricted in its breeding range to the islands of Labrador, it also would have been exterminated long ago.

Which of the following would you LEAST expect to be discussed elsewhere in the book from which this passage was taken?

Possible Answers:

The practice of sending messages by carrier pigeon

The raising of chickens for their eggs

The use of tropical birds’ feathers as hat decorations

The types of birds encountered by the first Antarctic explorers

Falconry

Correct answer:

The types of birds encountered by the first Antarctic explorers

Explanation:

The passage describes how humans use the eider down produced by eider ducks as a commodity for its insulating properties. Given this focus, along with the title of the book from which the passage is taken, The Utility of Birds, we can assume that other topics discussed in the books would deal with ways in which birds are useful to humans. “The use of tropical birds’ feathers as hat decorations,” “the raising of chickens for their eggs,” “falconry,” and “the practice of sending messages by carrier pigeon” all deal with ways in which birds are useful to humans, but “The types of birds encountered by the first Antarctic explorers” does not relate to how birds are useful to humans, so it would be least likely to be discussed elsewhere in a book called The Utility of Birds and is the correct answer.

Example Question #161 : Passage Based Questions

Adapted from “Feathers of Sea Birds and Wild Fowl for Bedding” from The Utility of Birds by Edward Forbush (ed. 1922)

In the colder countries of the world, the feathers and down of waterfowl have been in great demand for centuries as filling for beds and pillows. Such feathers are perfect non-conductors of heat, and beds, pillows, or coverlets filled with them represent the acme of comfort and durability. The early settlers of New England saved for such purposes the feathers and down from the thousands of wild-fowl which they killed, but as the population increased in numbers, the quantity thus furnished was insufficient, and the people sought a larger supply in the vast colonies of ducks and geese along the Labrador coast. 

The manner in which the feathers and down were obtained, unlike the method practiced in Iceland, did not tend to conserve and protect the source of supply. In Iceland, the people have continued to receive for many years a considerable income by collecting eider down, but there they do not “kill the goose that lays the golden eggs.” Ducks line their nests with down plucked from their own breasts and that of the eider is particularly valuable for bedding. In Iceland, these birds are so carefully protected that they have become as tame and unsuspicious as domestic fowls In North America. Where they are constantly hunted they often conceal their nests in the midst of weeds or bushes, but in Iceland, they make their nests and deposit their eggs in holes dug for them in the sod. A supply of the ducks is maintained so that the people derive from them an annual income.

In North America, quite a different policy was pursued. The demand for feathers became so great in the New England colonies about the middle of the eighteenth century that vessels were fitted out there for the coast of Labrador for the express purpose of securing the feathers and down of wild fowl. Eider down having become valuable and these ducks being in the habit of congregating by thousands on barren islands of the Labrador coast, the birds became the victims of the ships’ crews. As the ducks molt all their primary feathers at once in July or August and are then quite incapable of flight and the young birds are unable to fly until well grown, the hunters were able to surround the helpless birds, drive them together, and kill them with clubs. Otis says that millions of wildfowl were thus destroyed and that in a few years their haunts were so broken up by this wholesale slaughter and their numbers were so diminished that feather voyages became unprofitable and were given up. 

This practice, followed by the almost continual egging, clubbing, shooting, etc. by Labrador fishermen, may have been a chief factor in the extinction of the Labrador duck, that species of supposed restricted breeding range. No doubt had the eider duck been restricted in its breeding range to the islands of Labrador, it also would have been exterminated long ago.

Which of the following most likely happened after the Labrador feather voyages were no longer organized?

Possible Answers:

The quality of bedding in North America became preferable to that found in Iceland.

A population of the Labrador duck was reestablished.

North Americans imported eider down from Iceland.

The price of eider down in North America plummeted.

Eider down began to be used for other purposes in North America.

Correct answer:

North Americans imported eider down from Iceland.

Explanation:

The first paragraph tells us that the Labrador feather voyages were organized to keep up with an increased demand for eider down caused by an increased North American population. The passage doesn’t mention any alternative sources of eider down being used after the Labrador feather voyages were no longer organized. Therefore, we can eliminate the answer choice “The price of eider down in North America plummeted” since if eider down became more rare, its price would likely have gone up, not down. We can also eliminate the answer choice “Eider down began to be used for other purposes in North America” as this is not suggested in the passage at all and would require more information to be supported. “The quality of bedding in North America became preferable to that found in Iceland” cannot be correct either, as in the first paragraph, the author claims that eider down makes the best bedding, and if eider down becomes rare in North America, it’s not likely that the quality of North American bedding will exceed that of bedding made in Iceland, where eider down is assumed to be more available. “A population of the Labrador duck was reestablished.” cannot be the correct answer because the passage tells us that the Labrador duck went extinct, and if a species is extinct, there are no living members left from which populations of it could be reestablished. This leaves us with one answer, the correct one: “North American populations had to import eider down from Iceland.” This makes sense, as if less eider down were available in North America but there was still a desire for it, it would be likely to be imported from elsewhere in the world.

Example Question #1 : Science

Adapted from "Recent Views as to Direct Action of Light on the Colors of Flowers and Fruits" in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The theory that the brilliant colors of flowers and fruits is due to the direct action of light has been supported by a recent writer by examples taken from the arctic instead of from the tropical flora. In the arctic regions, vegetation is excessively rapid during the short summer, and this is held to be due to the continuous action of light throughout the long summer days. “The further we advance towards the north, the more the leaves of plants increase in size as if to absorb a greater proportion of the solar rays. M. Grisebach says that during a journey in Norway he observed that the majority of deciduous trees had already, at the 60th degree of latitude, larger leaves than in Germany, while M. Ch. Martins has made a similar observation as regards the leguminous plants cultivated in Lapland.” The same writer goes on to say that all the seeds of cultivated plants acquire a deeper color the further north they are grown, white haricots becoming brown or black, and white wheat becoming brown, while the green color of all vegetation becomes more intense. The flowers also are similarly changed: those which are white or yellow in central Europe becoming red or orange in Norway. This is what occurs in the Alpine flora, and the cause is said to be the same in both—the greater intensity of the sunlight. In the one the light is more persistent, in the other more intense because it traverses a less thickness of atmosphere.

Admitting the facts as above stated to be in themselves correct, they do not by any means establish the theory founded on them; and it is curious that Grisebach, who has been quoted by this writer for the fact of the increased size of the foliage, gives a totally different explanation of the more vivid colors of Arctic flowers. He says, “We see flowers become larger and more richly colored in proportion as, by the increasing length of winter, insects become rarer, and their cooperation in the act of fecundation is exposed to more uncertain chances.” (Vegetation du Globe, col. i. p. 61—French translation.) This is the theory here adopted to explain the colors of Alpine plants, and we believe there are many facts that will show it to be the preferable one. The statement that the white and yellow flowers of temperate Europe become red or golden in the Arctic regions must we think be incorrect. By roughly tabulating the colors of the plants given by Sir Joseph Hooker as permanently Arctic, we find among fifty species with more or less conspicuous flowers, twenty-five white, twelve yellow, eight purple or blue, three lilac, and two red or pink; showing a very similar proportion of white and yellow flowers to what obtains further south.

The author of the passage is most likely __________.

Possible Answers:

a geographer

a meteorologist

an archeologist

a chemist

a botanist

Correct answer:

a botanist

Explanation:

As the title of the passage is "Recent Views as to Direct Action of Light on the Colors of Flowers and Fruits" and its subject is flower color, leaf size, and other scientific phenomena that have to do with plants, trees, and especially flowers, we can safely infer that of the given answer choices, the author is most likely a botanist. While the author does discuss flowers at different latitudes, which may suggest "geographer," and different atmospheric conditions, which may suggest "meteorologist," he only broaches these topics because of how they intersect with his primary topic of flowers and plants.

Example Question #162 : Passage Based Questions

Adapted from "Recent Views as to Direct Action of Light on the Colors of Flowers and Fruits" in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The theory that the brilliant colors of flowers and fruits is due to the direct action of light has been supported by a recent writer by examples taken from the arctic instead of from the tropical flora. In the arctic regions, vegetation is excessively rapid during the short summer, and this is held to be due to the continuous action of light throughout the long summer days. "The further we advance towards the north, the more the leaves of plants increase in size as if to absorb a greater proportion of the solar rays. M. Grisebach says that during a journey in Norway he observed that the majority of deciduous trees had already, at the 60th degree of latitude, larger leaves than in Germany, while M. Ch. Martins has made a similar observation as regards the leguminous plants cultivated in Lapland.” The same writer goes on to say that all the seeds of cultivated plants acquire a deeper color the further north they are grown, white haricots becoming brown or black, and white wheat becoming brown, while the green color of all vegetation becomes more intense. The flowers also are similarly changed: those which are white or yellow in central Europe becoming red or orange in Norway. This is what occurs in the Alpine flora, and the cause is said to be the same in both—the greater intensity of the sunlight. In the one the light is more persistent, in the other more intense because it traverses a less thickness of atmosphere.

Admitting the facts as above stated to be in themselves correct, they do not by any means establish the theory founded on them; and it is curious that Grisebach, who has been quoted by this writer for the fact of the increased size of the foliage, gives a totally different explanation of the more vivid colors of Arctic flowers. He says, “We see flowers become larger and more richly colored in proportion as, by the increasing length of winter, insects become rarer, and their cooperation in the act of fecundation is exposed to more uncertain chances.” (Vegetation du Globe, col. i. p. 61—French translation.) This is the theory here adopted to explain the colors of Alpine plants, and we believe there are many facts that will show it to be the preferable one. The statement that the white and yellow flowers of temperate Europe become red or golden in the Arctic regions must we think be incorrect. By roughly tabulating the colors of the plants given by Sir Joseph Hooker as permanently Arctic, we find among fifty species with more or less conspicuous flowers, twenty-five white, twelve yellow, eight purple or blue, three lilac, and two red or pink; showing a very similar proportion of white and yellow flowers to what obtains further south.

This passage is taken from a longer work. Based on what you have read, which of the following would you most expect to find in the paragraphs immediately following those in the passage?

Possible Answers:

Further consideration of the theory of the writer quoted in the first paragraph

A discussion of the historical uses of alpine plants

More evidence as to why Grisebach’s theory is the correct one

A summary of a paper the author wishes to publish on the topic being discussed

Praise of the useful nature of Hooker’s research

Correct answer:

More evidence as to why Grisebach’s theory is the correct one

Explanation:

In the concluding sentences of the passage, the author is asserting that Grisebach's interpretation is the correct one, not that of the "recent writer" quoted in the first paragraph. The author is also bringing up evidence (Joseph Hooker's enumerated observations) to prove his point. One could thus reasonably expect to encounter "more evidence as to why Grisebach’s theory is the correct one" if one read on further in the larger text of which this passage is a small part.

Example Question #52 : Extrapolating From The Text In Natural Science Passages

Adapted from "Taking a Second Look: An Analysis of Genetic Markers in Species Relatedness" by Joseph Ritchie (2014)

Phylogenetics is the study of genetic composition in various species and is used by evolutionary biologists to investigate similarities in the molecular sequences of proteins in varying organisms. The amino acid sequences that build proteins are used to construct mathematical matrices that aid in determining evolutionary ties through the investigation of percentage similarities. The study of these matrices helps to expose evolutionary relationships between species that may not have the same overt characteristics.

Species adapt and evolve based on the pressures that exist in their environment. Climate, food source, and habitat availability are only a few factors that act on species adaptation. These stressors can alter the physical characteristics of organisms. This divergence in evolution has made it difficult to determine the interrelatedness of organisms by analyzing their physical characteristics alone.

For instance, looking only at physical characteristics, the ghost bat resembles a pigeon more than a spider monkey; however, phylogenetics has found that the amino acid sequences that construct the beta hemoglobin molecules of bats are twenty percent more similar to those of mammalian primates than those of birds. This helps reject the assumption that common physical characteristics between species are all that is needed to determine relatedness. 

The differences produced by divergent evolution observed in the forest-dwelling, arboreal spider monkey and the nocturnal, airborne ghost bat can be reconciled through homology. Homologous characteristics are anatomical traits that are similar in two or more different species. For instance, the bone structure of a spider monkey’s wrist and fingers greatly resembles that of a bat’s wing or even a whale’s fin. These similarities are reinforced by phylogenetic evidence that supports the idea that physically dissimilar species can be evolutionarily related through anatomical and genetic similarities.

A scientist studied the relatedness of several reptilian species solely by investigating fossil evidence and has concluded that physical characteristics alone are enough to determine species relatedness. Would this scientist agree with the claims made by phylogenetic research?

Possible Answers:

No, because phylogenetics assumes that physical traits and characteristics are not the only objective and reliable markers in the study of species relatedness.

Yes, because phylogenetics is second to physical comparisons and thus supports the archaeologist's position.

No, because phylogenetics is an unreliable and new technique that has yet to prove itself in major scientific arenas.

None of the other choices are correct.

Correct answer:

No, because phylogenetics assumes that physical traits and characteristics are not the only objective and reliable markers in the study of species relatedness.

Explanation:

The scientist studied relatedness based on the fossil record of physical traits. Having studied this, he would not agree with the notion that phylogenetics may better explain relatedness via genetic factors. The rest of the choices are incorrect because they are not supported by the passage.

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