GMAT Verbal : Comparing and Contrasting Ideas in and Aspects of Natural Science Passages

Study concepts, example questions & explanations for GMAT Verbal

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Example Questions

Example Question #1 : Textual Relationships In Science Passages

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

How does the quotation from Mr. Gosse relate to the evidence provided by other scientists earlier in the passage?

Possible Answers:

It contradicts the previous evidence and supports a different hypothesis.

It supports the same conclusions that the previous evidence supports.

It has nothing to do with the previous evidence.

It suggests that the earlier evidence applies not only to hummingbirds but to another type of bird as well.

It suggests that some of the previous evidence may be true, but some may be false.

Correct answer:

It supports the same conclusions that the previous evidence supports.

Explanation:

Let’s consider what Mr. Gosse is saying. The passage says, “Mr. Gosse also remarks, ‘All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.’”  Paraphrasing that, Mr. Gosse is saying that he has seen hummingbirds contort themselves in the air and he’s pretty sure they’re doing this in order to catch insects. The evidence provided by scientists earlier in the passage supports the idea that hummingbirds eat insects, just like Mr. Gosse’s does. We can’t say that Gosse’s evidence contradicts the earlier evidence, suggests that some of it may be false, or has nothing to do with the previous evidence. It also doesn’t suggest that the previous evidence can be applied to birds other than hummingbirds, because Mr. Gosse says that he is only discussing hummingbirds and we are to infer that the Polytmus is a hummingbird. So, the correct answer is that “it supports the same conclusions that the previous evidence supports.”

Example Question #2 : Textual Relationships In Science Passages

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

Which of the following does the author contrast in this passage?

Possible Answers:

Hummingbirds with long tails and hummingbirds with short tails

The author’s opinion about what hummingbirds eat and Mr. Gosse’s opinion about what hummingbirds eat

The results of feeding a hummingbird insects and the results of feeding a hummingbird flower nectar

Hummingbirds that eat flower nectar and hummingbirds that eat insects

The beliefs of historical scientists and the beliefs of scientists of the author’s time

Correct answer:

The beliefs of historical scientists and the beliefs of scientists of the author’s time

Explanation:

Nowhere in the passage is the feeding of hummingbirds by humans mentioned, so “The results of feeding a hummingbird insects and the results of feeding a hummingbird flower nectar” cannot be correct. While a hummingbird with a long tail, the Polytmus, is mentioned, it is not contrasted with any short-tailed hummingbirds. The author appears to agree with Mr. Gosse’s opinion about what hummingbirds eat, so “The author’s opinion about what hummingbirds eat and Mr. Gosse’s opinion about what hummingbirds eat” cannot be correct either. This leaves us with “Hummingbirds that eat flower nectar and hummingbirds that eat insects” and “the beliefs of historical scientists and the beliefs of scientists of the author’s time.” While the passage is concerned with what hummingbirds eat, it doesn’t suggest that some types of hummingbirds eat only nectar and others eat only insects. Hummingbirds are considered as an entire group; they’re never divided into “hummingbirds that eat insects” and “hummingbirds that eat flower nectar.” This leaves us with one answer choice, the correct one: “The beliefs of historical scientists and the beliefs of scientists of the author’s time.” These beliefs are contrasted in the paragraph’s second sentence: “All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects.”

Example Question #3 : Textual Relationships In Science Passages

Adapted from “Birds in Retreat” in “Animal Defences—Active Defence” in 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)

Among the large running birds are forms, like the African ostrich, in which the absence of powers of flight is largely compensated by the specialization of the legs for the purpose of rapid movement on the ground. For straightforward retreat in open country nothing could be more effective; but another kind of adaptation is required in birds like rails, which are deficient in powers of flight, and yet are able to run through thickly-growing vegetation with such rapidity as to commonly elude their enemies. This is rendered possible by the shape of their bodies, which are relatively narrow and flattened from side to side, so as to easily slip between the stems of grasses, rushes, and similar plants. Anyone who has pursued our native land-rail or corn-crake with intent to capture will have noted how extremely difficult it is even to get within sight of a bird of this sort. 

Certain birds, unfortunately for themselves, have lost the power of flight without correspondingly increased powers of running, and have paid the penalty of extinction. Such an arrangement, as might be anticipated, was the result of evolution in islands devoid of any predatory ground-animals, and a classic example of it is afforded by the dodo and its allies, birds related to the pigeons. The dodo itself was a large and clumsy-looking species that at one time abounded in the island of Mauritius, which, like oceanic islands generally, possessed no native mammals, while its indigenous reptiles were only represented by lizards. The ubiquitous sailor, however, and the animals (especially swine) which he introduced, brought about the extinction of this helpless bird in less than a century after its first discovery in 1598. Its memory is now only kept green by a few contemporary drawings and descriptions, certain museum remains, and the proverb "as extinct as a dodo.” A similar fate must overtake any organism suddenly exposed to new and unfavorable conditions, if devoid of sufficient plasticity to rapidly accommodate itself to the altered environment.

One of the main differences between an ostrich and a rail, according to the passage, is __________.

Possible Answers:

ostriches are smaller than rails

ostriches use their running abilities to catch prey, whereas rails use their running abilities to avoid predators

ostriches are living things whereas rails are inanimate objects

ostriches run over open terrain, and rails run through thick grass 

ostriches live in grassy areas whereas rails live in the desert

Correct answer:

ostriches run over open terrain, and rails run through thick grass 

Explanation:

Ostriches and rails are discussed in the first paragraph. The author says that “For straightforward retreat in open country nothing could be more effective; but another kind of adaptation is required in birds like rails, which are deficient in powers of flight, and yet are able to run through thickly-growing vegetation with such rapidity as to commonly elude their enemies.” The passage then goes on to detail how rails have thin bodies that allow them to dart through the grass. This means that the correct answer is “ostriches run over open terrain whereas rails run through thick grass.” 

The passage is describing the rail, a type of bird, and not using the word “rail” to describe part of a train track or a barrier on an elevated area, so “ostriches are living things whereas rails are inanimate objects” cannot be correct. Ostriches are never said to be smaller than rails or predators, so neither “ostriches are smaller than rails” nor “ostriches use their running abilities to catch prey, whereas rails use their running abilities to avoid predators” can be correct. Finally, rails are said to live in areas containing and have adapted to “thickly-growing vegetation” and ostriches are said to have developed a different adaptation suited to “open country,” so “ostriches live in grassy areas whereas rails live in the desert” cannot be correct either.

Example Question #2 : Textual Relationships In 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.

For what reason does the author describe the Irish hare as “vegetarian” in the underlined sentence?

Possible Answers:

To encourage the reader to switch to a vegetarian diet

To help readers empathize with the hare

To provide information about the hare's diet that the reader may not know

To contrast the hare with the stoat and the weasel

To provide insight about what food is available in arctic environments

Correct answer:

To contrast the hare with the stoat and the weasel

Explanation:

The underlined sentence is the last sentence of the third paragraph, “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. One could reasonably infer that a hare would be vegetarian, so “To provide information about the hare’s diet that the reader may not know” cannot be the correct answer. The section doesn’t aim to help readers empathize with the hare any more than the stoat and weasel, so “To help readers empathize with the hare” cannot be correct either. The sentence doesn’t specifically encourage the reader to do anything; it is merely providing information about certain animals; so, “To encourage the reader to switch to a vegetarian diet” cannot be correct. “To provide insight about what food is available in arctic environments” doesn’t make sense either, because we are not told about the food specifically available in arctic environments; we can’t even assume that there are only plants available, as the stoat and weasel eat meat. That brings us to the correct answer: “To contrast the hare with the stoat and the weasel.” The word “vegetarian” specifically contrasts with the word “carnivorous” used later in the sentence to describe the stoat and weasel. This contrast mirrors the contrast of defensive and aggressive/defensive color-changing adaptations which the author is discussing in the sentence.

Example Question #114 : Content Of Natural Science Passages

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

What do Azara, Bullock, and Waterton have in common?

Possible Answers:

They are all types of birds that eat insects.

They are all scientists who think hummingbirds eat insects.

They are all types of hummingbirds.

They are all critics of the writer and disagree with his theory.

They are all scientists who think hummingbirds eat flower nectar.

Correct answer:

They are all scientists who think hummingbirds eat insects.

Explanation:

Azara, Bullock, and Waterton are all mentioned near the beginning of the passage. The author writes, “All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects.” He then mentioned the following:

(1) "Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers."

(2) "Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs."

(3) "Waterton made a similar statement."

The author is suggesting that Azara, Bullock, and Waterton fall into the group of “every close observer of their habits.” The three also make statements about hummingbirds. From this, we can narrow down our answers to three choices: that Azara, Bullock, and Waterton are critics of the author, scientists who think hummingbirds eat insects, or scientists who think hummingbirds eat flower nectar. Nowhere in the passage do the statements made by these writers appear to contradict the author’s opinion, so we can discard the idea that Azara, Bullock, and Waterton are critics of the author. So, are they saying that hummingbirds eat flower nectar or insects? They author says that early observers of hummingbirds thought that they eat flower nectar, but that more recent scientists—like the three quoted—think that they eat insects. The statements made by each also relate to hummingbirds eating insects, so the correct answer is “They are all scientists who think hummingbirds eat insects.”

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