SAT Critical Reading : Analyzing Main Idea, Theme, and Purpose in Natural Science Passages

Study concepts, example questions & explanations for SAT Critical Reading

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Example Question #62 : Psat Critical Reading

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 best states the main idea of this passage?

Possible Answers:

Natural resources are precious.

Eider down is valuable as a source of bedding, leading to its collection from ducks.

The Icelandic people collect eider down in an efficient and reasonable way.

The extinction of the Labrador duck can be traced to a definite cause.

The North American and Icelandic methods of collecting eider down have had vastly different consequences. 

Correct answer:

The North American and Icelandic methods of collecting eider down have had vastly different consequences. 

Explanation:

Questions that ask about a passage’s main idea need to encompass each of the topics it discusses while not describing them in a way that is too broad. We can ignore any answer choices that only describe parts of the passage—here, “Eider down is valuable as a source of bedding, leading to its collection from ducks,” “The extinction of the Labrador duck can be traced to a definite cause,” and “The Icelandic people collect eider down in an efficient and reasonable way.” This leaves us with “Natural resources are precious,” which is far too broad to accurately describe the passage’s main idea, and the correct answer, “The North American and Icelandic methods of collecting eider down have had vastly different consequences.”

Example Question #1 : Natural Sciences

"Darwin and His Influence" by Joseph Ritchie (2014)

In this passage, “selection” refers to traits that are selected for and passed on to later generations, and “species” refers to organisms that share a common ancestor and can produce viable offspring with one another.

     Early in the nineteenth century, scientists sought to understand the differences in the earth’s flora and fauna from their archeological ancestors. The prevailing view at the time was that the differences between current and previous species were unremarkable deviations from their Platonic ideal forms. This theory hinged upon the ideals of the religious-based “created kinds” theory, which state that individuals of today are products of the organisms that were present at the earth’s creation, the result of an intelligent designer. Furthermore, these individuals believed that the differences between organisms could be explained by unseen geological and astrological forces acting on organisms slowly, throughout time. Other scientists also believed that individuals had the ability to change within their lifetimes and pass on traits to their offspring efficiently and quickly through a single generation.

     Charles Darwin and other biologists, such as Alfred Wallace, were not greatly influenced by these views and hypotheses. Their propositions stated that species evolve over many generations, due to the selective pressures of their given environments. This evolution could result in the generation of divergent traits, as well as speciation and separation from the original ancestral species. The concept that organisms were not finite or present since creation was very controversial to the scientists of the period. Some saw such an idea as unsupportable, while others perceived it as heretical and fanatical.

     Darwin set out to find support for his theory through his work, On the Origins of Species by Means of Natural Selection. He was influenced by archeological discoveries of species, which appeared to have vastly different physiological appearances from present-day organisms. Darwin decided to sail around the world on a Royal Navy ship named the H.M.S. Beagle. During his travels, he was taken to the Pacific islands of the Galapagos archipelago. The volcanic islands followed a patterned distribution on either side of the Equator. The landscapes of each island varied, with different observable flora and fauna. Through scientific observations, Darwin noticed subtle variations of finches on different islands. Some finches had large hard beaks, while others had slender beaks. Beaks were differentiated from island to island. After careful study, Darwin noticed that the beaks seemed to match the food source on each island. The large beaks were specialized for breaking open hard-shelled nuts, while the slender beaks were specialized for eating certain fruits that were abundant. Darwin hypothesized that an ancestral species of finch landed on the islands, and that over generations they became adapted to the locally abundant food sources. 

     Darwin compiled multiple instances of natural selection and incorporated discoveries made by archeologists and physiologists. He surmised that species evolve over time due to the selective pressures of their respective habitats. These events occur slowly over many generations. Each species selects for advantageous traits among its members. Over time, traits selected as advantageous by environmental pressures and stressors become commonplace in the species. This niche-forming process specializes species by rewarding those with traits most suitable for reproductive success. These traits may progress into speciation of the original species, which results in the eventual development of an entirely new species. Darwin’s theory was met with opposition at the time of its publication, and the theory of evolution remains a controversial topic in several arenas of debate.

What is the main point of this passage?

Possible Answers:

The main point is to describe the ways finches of the Galapagos adapt to their environments.

The main point is to compare and contrast the viewpoints of early nineteenth-century scientists.

The main point is to illustrate Darwin's journey and formulation of the theory of natural selection.

The main point is to illustrate the mechanics of natural selection.

Correct answer:

The main point is to illustrate Darwin's journey and formulation of the theory of natural selection.

Explanation:

The main point is to illustrate Darwin's journey and formulation of the theory of natural selection.

This answer is correct because it is the main focal point of the entire passage. Each of the other answers are incorrect because they are the focus points of parts of the passage but not the passage as a whole. The main purpose of this passage is to describe Darwin's journey and the influences used to formulate his theory of evolution by natural selection.

Example Question #61 : Passage Based Questions

"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.

What can we say, in general, about the interpretations that have been offered for the effects of Copernicus’ discoveries?

Possible Answers:

They have been used more according to the disposition of their interpreters than in accord with the reality of the facts.

They have provided the grounds for a fruitful dialogue between religion and science.

They have unlocked a number of themes that were long hidden by the powers of religion and authoritarian regimes.

None of the other answers

They have been abused for tyrannical purposes by many parties.

Correct answer:

They have been used more according to the disposition of their interpreters than in accord with the reality of the facts.

Explanation:

While the passage does catalogue two different worldviews that emerged from Copernicus' findings, it ultimately stresses the point that such outlooks are both limited because of their adherents' biases. Neither of them really reads the history or even the general images correctly. It seems that each one uses the findings as an occasion for strengthening his or her outlook on reality, whatever that might be.

Example Question #61 : Natural 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.

Why is the "Copernican revolution" of the human sciences contrary to the literal sense of Copernicus' findings?

Possible Answers:

None of the other answers

Copernicus' findings were scientific in contrast to nebulous humanistic aims.

Copernicus' findings aim only at disproving a former worldview, not finding new data around a new center of experience.

Copernicus' findings were focused on a new external "center," drawing attention away from the immediate center experienced in day-to-day life.

Copernicus' scientific aims immediately prove the fact that the human person is merely a speck on a rock in a large universe.

Correct answer:

Copernicus' findings were focused on a new external "center," drawing attention away from the immediate center experienced in day-to-day life.

Explanation:

The key sentence for this question is: "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." To start looking at the sun as the center requires us to "look outward" in a new way, not paying attention to our particular earth-bound viewpoint. However, the "Copernican revolution" centered on humanity does just the opposite. It turns the gaze "inward," quite different from the literal sense of Copernicus' findings.

Example Question #1 : Analyzing Main Idea, Theme, And Purpose In Natural Science Passages

"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 primary goal of this passage is __________.

Possible Answers:

To argue against the use of lesion studies

To convince readers that lesion studies are more effective than all other neuroscience studies and to present the opinion that lesion studies are valuable and should be used in combination with other techniques

To provide the reader with a thorough understanding of the terms “correlational” and “causational”

To discuss the specific limitations of all neuroscience methods

To present the opinion that lesion studies are valuable and should be used in combination with other techniques

Correct answer:

To present the opinion that lesion studies are valuable and should be used in combination with other techniques

Explanation:

While "to convince readers that lesion studies are more effective than all other neuroscience studies and to present the opinion that lesion studies are valuable and should be used in combination with other techniques" may seem correct at first, on close inspection, the passage indicates that lesion studies should be used in convergence with other methods and does not directly discuss the effectiveness of lesion studies in comparison with other methods. "To discuss the specific limitations of all neuroscience methods" is incorrect because no specific limitations are cited. "To provide the reader with a thorough understanding of the terms 'correlational' and 'causational'" may seem like a viable option because the passage does address these concepts, but they are not the core tenet of the passage. "To present the opinion that lesion studies are valuable and should be used in combination with other techniques" is correct because the passage repeatedly comments on the use of convergent techniques, including lesion studies, to better understand the brain.

 

Example Question #111 : Science

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.

Which of the following best expresses the main idea of the passage?

Possible Answers:

All animals that live in a changing environment change color.

The Scottish hare changes its fur color.

Increased defense is the only reason for an animal to change its fur color.

Animals like the stoat, the weasel, and the Irish hare are better adapted to changing environments than to unchanging ones.

Certain animals change their fur color to be better predators or better at hiding.

Correct answer:

Certain animals change their fur color to be better predators or better at hiding.

Explanation:

When answering questions about the main idea of a passage, it’s important to pick out an answer choice to which each paragraph relates, but one that isn’t too broad. Some of the answer choices to this question are too specific: “The Scottish hare changes its fur color” is, and we can tell because the first paragraph doesn’t say anything about the Scottish hare, and the third paragraph only mentions it in its last line. “Increased defense is the only reason for an animal to change its fur color” should get your attention due to its use of the word “only”—did we hear anything in the passage about color-changing adaptations being used “only” for defense? No, we heard the opposite, in the passage’s last line: “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.” The language may be a bit dense here, but what the passage is saying is that the hare uses its color-changing adaptation for defense, but stoats and weasels use it for being better predators and sneaking up on their prey—definitely not a defensive use. Similarly, “All animals that live in a changing environment change color” is making a strong statement due to its use of the word “all.” The passage gives us a few examples of animals that change that live in a changing environment and change their color, but this isn’t enough for us to assume that all animals that live in changing environments act this way. 

Example Question #1 : Understanding Style, Argument, And Organization In 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.

The purpose of the passage’s third paragraph is __________.

Possible Answers:

to describe an animal that has adapted to an unchanging environment

to describe the appearance of a stoat in summer

to provide an example color-change in animals that is both aggressive and defensive

to describe why stoats and weasels have a hard time hunting Irish hares in winter

to provide an example of an animal that goes by two different names depending on its appearance

Correct answer:

to provide an example color-change in animals that is both aggressive and defensive

Explanation:

When answering questions about a paragraph’s purpose, it’s helpful to consider how it relates to the rest of the passage as a whole, and to consider what each of the other paragraphs do in the context of the passage. For instance, in this passage, the first paragraph transitions from discussing animal adaptations in unchanging environments to discussing animal adaptations in changing environments. The second paragraph talks about Irish hares as an example of animals that change their fur color. So, what is the point of the third paragraph? While it does “provide an example of an animal that goes by two different names depending on its appearance” and “describe the appearance of a stoat in summer,” neither of these is its main point; these are details, and neither seems to relate that much to the points of the previous paragraphs. Stoats and weasels are not described as specifically hunting Irish hares, and the passage describes how their changing fur color helps them be better hunters, not why they have such a hard time hunting, so “to describe why stoats and weasels have a hard time hunting Irish hares in winter” cannot be the correct answer either. The point of the paragraph cannot be “to describe an animal that has adapted to an unchanging environment” either, because it describes stoats and weasels, animals that adapt to changing environments. This leaves us with one answer, the correct one: “to provide an example color-change in animals that is both aggressive and defensive.” The examples of stoats and weasels both fall into this category, which is contrasted with the purely defensive function of color-change in hares in the passage’s last sentence.

Example Question #51 : Psat Critical Reading

Adapted from Essays on Early Ornithology and Kindred Subjects by James R. McClymont (1920)

The voyagers named it the Angra de Santa Elena, and it may have been the bay which is now known as St. Helen’s Bay. But it is worthy of note that the G. de Sta. Ellena of the Cantino Chart is laid down in a position which corresponds rather with that of Table Bay than with that of St. Helen’s Bay.

The Portuguese came into contact with the inhabitants of the country adjacent to the anchorage. These people had tawny complexions, and carried wooden spears tipped with horn—assagais of a kind—and bows and arrows. They also used foxes’ tails attached to short wooden handles. We are not informed for what purposes the foxes’ tails were used. Were they used to brush flies away, or were they insignia of authority? The food of the natives was the flesh of whales, seals, and antelopes (gazellas), and the roots of certain plants. Crayfish or ‘Cape lobsters’ abounded near the anchorage.

The author of the roteiro affirms that the birds of the country resembled the birds in Portugal, and that amongst them were cormorants, larks, turtle-doves, and gulls. The gulls are called "guayvotas," but "guayvotas" is probably another instance of the eccentric orthography of the author and equivalent to "gaivotas."

In December the squadron reached the Angra de São Bràs, which was either Mossel Bay or another bay in close proximity to Mossel Bay. Here penguins and seals were in great abundance. The author of the roteiro calls the penguins "sotelycairos," which is more correctly written "sotilicarios" by subsequent writers. The word is probably related to the Spanish "sotil" and the Latin "subtilis," and may contain an allusion to the supposed cunning of the penguins, which disappear by diving when an enemy approaches.

The sotilicarios, says the chronicler, could not fly because there were no quill-feathers in their wings; in size they were as large as drakes, and their cry resembled the braying of an ass. Castanheda, Goes, and Osorio also mention the sotilicario in their accounts of the first voyage of Vasco da Gama, and compare its flipper to the wing of a bat—a not wholly inept comparison, for the under-surface of the wings of penguins is wholly devoid of feathery covering. Manuel de Mesquita Perestrello, who visited the south coast of Africa in 1575, also describes the Cape penguin. From a manuscript of his Roteiro in the Oporto Library, one learns that the flippers of the sotilicario were covered with minute feathers, as indeed they are on the upper surface and that they dived after fish, upon which they fed, and on which they fed their young, which were hatched in nests constructed of fishbones. There is nothing to cavil at in these statements, unless it be that which asserts that the nests were constructed of fishbones, for this is not in accordance with the observations of contemporary naturalists, who tell us that the nests of the Cape Penguin (Spheniscus demersus) are constructed of stones, shells, and debris. It is, therefore, probable that the fishbones which Perestrello saw were the remains of repasts of seals.

Seals, says the roteiro, were in great number at the Angra de São Bràs. On one occasion the number was counted and was found to be three thousand. Some were as large as bears and their roaring was as the roaring of lions. Others, which were very small, bleated like kids. These differences in size and in voice may be explained by differences in the age and in the sex of the seals, for seals of different species do not usually resort to the same locality. The seal which formerly frequented the south coast of Africa—for it is, I believe, no longer a denizen of that region—was that which is known to naturalists as Arctocephalus delalandii, and, as adult males sometimes attain eight and a half feet in length, it may well be described as of the size of a bear. Cubs from six to eight months of age measure about two feet and a half in length. The Portuguese caught anchovies in the bay, which they salted to serve as provisions on the voyage. They anchored a second time in the Angra de São Bràs in March, 1499, on their homeward voyage.

Yet one more allusion to the penguins and seals of the Angra de São Bràs is of sufficient historical interest to be mentioned. The first Dutch expedition to Bantam weighed anchor on the 2nd of April, 1595, and on the 4th of August of the same year the vessels anchored in a harbor called "Ague Sambras," in eight or nine fathoms of water, on a sandy bottom. So many of the sailors were sick with scurvy—"thirty or thirty-three," said the narrator, "in one ship"—that it was necessary to find fresh fruit for them. "In this bay," runs the English translation of the narrative, "lieth a small Island wherein are many birds called Pyncuins and sea Wolves that are taken with men’s hands." In the original Dutch narrative by Willem Lodewyckszoon, published in Amsterdam in 1597, the name of the birds appears as "Pinguijns."

What is the main idea of the first paragraph?

Possible Answers:

The shoreline was meticulously mapped.

There are discrepancies between the names and the places mapped. 

The men who named the bay were deeply religious.

The sailors did not know where they were going.

The voyagers showed no interest in the animals they encountered.

Correct answer:

There are discrepancies between the names and the places mapped. 

Explanation:

The purpose of this paragraph is to illustrate the location the text it is concerned with. It says that it is important to note that what was called “Angra de Santa Elena” by the voyagers does not correspond fully to “St. Helen’s Bay.” Instead it is closer to “Table bay” on a certain map or “chart."

Example Question #1 : Understanding The Content Of Natural Science Passages

Adapted from Essays on Early Ornithology and Kindred Subjects by James R. McClymont (1920)

The voyagers named it the Angra de Santa Elena, and it may have been the bay which is now known as St. Helen’s Bay. But it is worthy of note that the G. de Sta. Ellena of the Cantino Chart is laid down in a position which corresponds rather with that of Table Bay than with that of St. Helen’s Bay.

The Portuguese came into contact with the inhabitants of the country adjacent to the anchorage. These people had tawny complexions, and carried wooden spears tipped with horn—assagais of a kind—and bows and arrows. They also used foxes’ tails attached to short wooden handles. We are not informed for what purposes the foxes’ tails were used. Were they used to brush flies away, or were they insignia of authority? The food of the natives was the flesh of whales, seals, and antelopes (gazellas), and the roots of certain plants. Crayfish or ‘Cape lobsters’ abounded near the anchorage.

The author of the roteiro affirms that the birds of the country resembled the birds in Portugal, and that amongst them were cormorants, larks, turtle-doves, and gulls. The gulls are called "guayvotas," but "guayvotas" is probably another instance of the eccentric orthography of the author and equivalent to "gaivotas."

In December the squadron reached the Angra de São Bràs, which was either Mossel Bay or another bay in close proximity to Mossel Bay. Here penguins and seals were in great abundance. The author of the roteiro calls the penguins "sotelycairos," which is more correctly written "sotilicarios" by subsequent writers. The word is probably related to the Spanish "sotil" and the Latin "subtilis," and may contain an allusion to the supposed cunning of the penguins, which disappear by diving when an enemy approaches.

The sotilicarios, says the chronicler, could not fly because there were no quill-feathers in their wings; in size they were as large as drakes, and their cry resembled the braying of an ass. Castanheda, Goes, and Osorio also mention the sotilicario in their accounts of the first voyage of Vasco da Gama, and compare its flipper to the wing of a bat—a not wholly inept comparison, for the under-surface of the wings of penguins is wholly devoid of feathery covering. Manuel de Mesquita Perestrello, who visited the south coast of Africa in 1575, also describes the Cape penguin. From a manuscript of his Roteiro in the Oporto Library, one learns that the flippers of the sotilicario were covered with minute feathers, as indeed they are on the upper surface and that they dived after fish, upon which they fed, and on which they fed their young, which were hatched in nests constructed of fishbones. There is nothing to cavil at in these statements, unless it be that which asserts that the nests were constructed of fishbones, for this is not in accordance with the observations of contemporary naturalists, who tell us that the nests of the Cape Penguin (Spheniscus demersus) are constructed of stones, shells, and debris. It is, therefore, probable that the fishbones which Perestrello saw were the remains of repasts of seals.

Seals, says the roteiro, were in great number at the Angra de São Bràs. On one occasion the number was counted and was found to be three thousand. Some were as large as bears and their roaring was as the roaring of lions. Others, which were very small, bleated like kids. These differences in size and in voice may be explained by differences in the age and in the sex of the seals, for seals of different species do not usually resort to the same locality. The seal which formerly frequented the south coast of Africa—for it is, I believe, no longer a denizen of that region—was that which is known to naturalists as Arctocephalus delalandii, and, as adult males sometimes attain eight and a half feet in length, it may well be described as of the size of a bear. Cubs from six to eight months of age measure about two feet and a half in length. The Portuguese caught anchovies in the bay, which they salted to serve as provisions on the voyage. They anchored a second time in the Angra de São Bràs in March, 1499, on their homeward voyage.

Yet one more allusion to the penguins and seals of the Angra de São Bràs is of sufficient historical interest to be mentioned. The first Dutch expedition to Bantam weighed anchor on the 2nd of April, 1595, and on the 4th of August of the same year the vessels anchored in a harbor called "Ague Sambras," in eight or nine fathoms of water, on a sandy bottom. So many of the sailors were sick with scurvy—"thirty or thirty-three," said the narrator, "in one ship"—that it was necessary to find fresh fruit for them. "In this bay," runs the English translation of the narrative, "lieth a small Island wherein are many birds called Pyncuins and sea Wolves that are taken with men’s hands." In the original Dutch narrative by Willem Lodewyckszoon, published in Amsterdam in 1597, the name of the birds appears as "Pinguijns."

One of the main points made in the last paragraph is __________.

Possible Answers:

The seals and penguins seen had flippers like men's hands.

The Dutch narrative of the expedition was printed within a year of the events.

The expedition stayed anchored in the bay for four months.

The English translation of the account is incomplete.

The expedition had to stop on the coast due to numerous cases of malnutrition aboard. 

Correct answer:

The expedition had to stop on the coast due to numerous cases of malnutrition aboard. 

Explanation:

The expedition had to stop at least once because around thirty-three of the sailors had "scurvy," which is a disease resulting from a deficiency of vitamin C. This was usually prevalent on ships, where sailors' diet were poor that they developed the disease due to malnutrition.

Example Question #161 : Content Of 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 mathmatical 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.

The central idea of this passage is best described by which of the following statements?

Possible Answers:

Understanding divergent evolution is necessary for understanding species relatedness.

Phylogenetics is a relatively new area of study and has yet to yield supported conclusions on evolutionary histories.

Genetic analysis is the only method of studying evolutionary ties and species relatedness.

Despite differences in physical appearance, genetic similarities can aid in determining species relatedness and evolutionary histories.

Correct answer:

Despite differences in physical appearance, genetic similarities can aid in determining species relatedness and evolutionary histories.

Explanation:

This is the correct answer because it is the only statement that is supported by the passage. The passage introduces the field of phylogenetics and the need to explore evolution beyond simple examination of physical characteristics. It does not state which field of study is better or correct. It simply states that they compliment the same cause: the study of relatedness. The other choices are unsupported opinions. The answer choice about divergent evolution is incorrect because while the passage's fourth paragraph is about divergent evolution, the entire passage encompasses many more topics.

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