GMAT Verbal : Natural Science Passages

Study concepts, example questions & explanations for GMAT Verbal

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Example Questions

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Example Question #1 : Tone, Audience, And Point Of View In Natural 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.

Which of the following best describes the tone the author employs throughout the passage?

Possible Answers:

Furious

Carefree

None of the other answers

Despondent

Oversensitive

Correct answer:

None of the other answers

Explanation:

The author’s tone throughout the passage may not stick out as you are reading it. Even though he discusses the extinction of the dodo, he relates the events without being emotional about them, and ends with a scientific principle about how this can happen to other species. Thus, we cannot say that he is “oversensitive” about these issues or any others, or similarly, that he is “despondent” (feeling hopeless, pessimistic, and sad) or “furious” (extremely angry) about the dodo’s extinction. Nothing in the passage suggests that the author’s tone is “carefree” either, as he obviously thinks the dodo’s extinction is an important example of what can happen when a species cannot adapt fast enough to a too-quickly-changing environment. This leaves us with one answer, the correct one: “None of the other answers.”

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 tone of this passage is best described as __________.

Possible Answers:

optimistic

considerate

angry

objective

judgmental

Correct answer:

objective

Explanation:

The author’s tone in this passage is one that you may not even have noticed when reading the passage. Science passages like this one often employ a detached, impersonal, and neutral tone that can be called “objective.” This type of tone doesn’t involve the writer’s opinion or take sides with one or another of the topics being discussed. For instance, if the writer made the hares seem pitiable and the stoats seem like mean, bloodthirsty predators, his tone could not be said to be “objective.” However, the writer treats the stoats and hares in much the same way, discussing them in terms of their changing coat colors. “Objective” is the best answer for this question because we cannot support the assertions that the author’s tone is “angry,” “optimistic,” “considerate,” or “judgmental.”

Example Question #1 : Natural Science Passages

 Passage adapted from Animal Sanctuaries in Labrador (1911) by W. Wood

A sanctuary may be defined as a place where Man is passive and the rest of Nature active. Till quite recently Nature had her own sanctuaries, where man either did not go at all or only as a tool-using animal in comparatively small numbers. But now, in this machinery age, there is no place left where man cannot go with overwhelming forces at his command. He can strangle to death all the nobler wild life in the world to-day. To-morrow he certainly will have done so, unless he exercises due foresight and self-control in the mean time.

There is not the slightest doubt that birds and mammals are now being killed off much faster than they can breed. And it is always the largest and noblest forms of life that suffer most. The whales and elephants, lions and eagles, go. The rats and flies, and all mean parasites, remain. This is inevitable in certain cases. But it is wanton killing off that I am speaking of to-night. Civilized man begins by destroying the very forms of wild life he learns to appreciate most when he becomes still more civilized. The obvious remedy is to begin conservation at an earlier stage, when it is easier and better in every way, by enforcing laws for close seasons, game preserves, the selective protection of certain species, and sanctuaries.

I have just defined a sanctuary as a place where man is passive and the rest of Nature active. But this general definition is too absolute for any special case. The mere fact that man has to protect a sanctuary does away with his purely passive attitude. Then, he can be beneficially active by destroying pests and parasites, like bot-flies or mosquitoes, and by finding antidotes for diseases like the epidemic which periodically kills off the rabbits and thus starves many of the carnivora to death. But, except in cases where experiment has proved his intervention to be beneficial, the less he upsets the balance of Nature the better, even when he tries to be an earthly Providence.

It can be inferred that the passage is __________.

Possible Answers:

extracted from an incisive editorial column

taken from the newsletter of a nature club

from an article published in a scientific journal 

an excerpt from a lecture to an educated audience

an argument delivered to a court of law 

Correct answer:

an excerpt from a lecture to an educated audience

Explanation:

In the second paragraph, we find the contextual info we are looking for: “I am speaking of tonight”. From this we can assuredly infer that the words were delivered orally, and the elevated content implies an educated audience.

Example Question #1 : Understanding Main Ideas In 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.”

The purpose of this passage is __________.

Possible Answers:

to explain why one should feed a captive hummingbird insects and not flower nectar

to consider the opinions of scientists on what hummingbirds eat

to discuss the Polytmus’ feeding habits

to critique the opinions of other scientists

to propose a definitive experiment about what hummingbirds eat

Correct answer:

to consider the opinions of scientists on what hummingbirds eat

Explanation:

When answering questions about a passage’s purpose or main idea, it’s important to pick an answer choice that is broad enough to encompass the entire passage. For instance, while the Polytmus’ feeding habits are discussed in the passage, it can’t be said to be the purpose of the passage, since it’s only mentioned as a small detail. The passage can’t be said to critique the opinions of other scientists, because for the most part, the author quotes findings by scientists with whom he does not disagree. A definitive experiment is never proposed, and captive hummingbirds are never discussed. The passage does provide the opinions of scientists on what hummingbirds eat; this accurately captures the intent of the entire passage, not just some of its parts, and doesn’t state it too broadly.

Example Question #1 : Understanding Main Ideas In Natural 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.

Which of the following best states the main idea of this passage?

Possible Answers:

Birds employ a variety of defenses for avoiding predators.

The African ostrich’s strong leg muscles makes it well adapted to its environment.

Flightless birds adapt to their particular surroundings.

The extinction of the dodo can be traced to human causes.

Flightless birds sometimes develop strong running abilities, but if they don’t, they may be threatened with extinction.

Correct answer:

Flightless birds sometimes develop strong running abilities, but if they don’t, they may be threatened with extinction.

Explanation:

When asked to identify a passage’s main idea, it is important to pick out an answer choice to which all of the paragraphs can relate, but that is not too broad in including things that the passage does not discuss. Considering if each of the answer choices falls into one or another of these categories can help you narrow down your choices. For instance, “Birds employ a variety of defenses for avoiding predators” is far too broad to accurately describer this passage’s main idea. The author only discusses flightless birds, not all birds. “Flightless birds adapt to their particular surroundings” cannot be correct either, as the first paragraph discusses this, but the second paragraph discusses a flightless bird that did not adapt to its surroundings. Since the second paragraph can’t relate to this answer, it can’t be the main idea of the entire passage. Two of the remaining answer choices can be discarded due to their being too detailed: “The African ostrich’s strong leg muscles makes it well adapted to its environment” and “The extinction of the dodo can be traced to human causes.” While the first of these choices is stated in the first paragraph and the second is stated in the second paragraph, neither relates to the other paragraph, or even adequately summarizes the entire paragraph in which it appears. This leaves us with one answer choice, the correct one: “Flightless birds sometimes develop strong running abilities, but if they don’t, they may be threatened with extinction.” Each of the two paragraphs can relate to this answer choice, but it doesn’t include things that the passage doesn’t discuss.

Example Question #11 : Identifying And Analyzing Main Idea And Theme 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.

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

Possible Answers:

All animals that live in a changing environment change color.

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

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

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

The Scottish hare changes its fur color.

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 #2 : Finding Context Dependent Meanings Of Phrases In Narrative 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 can we infer from the author’s use of the underlined phrase, “sometimes, but not generally”?

Possible Answers:

None of the other answers

Hummingbirds can be found with insects in their stomachs, but this is rare.

Hummingbirds can be found with both honey and insects in their stomachs, and this is what scientists observe most often.

Hummingbirds can be found with honey in their stomachs, but it is not common.

Hummingbirds can be found with only honey in their stomachs quite often.

Correct answer:

Hummingbirds can be found with honey in their stomachs, but it is not common.

Explanation:

The phrase “sometimes, but not generally” is found in the sentence, “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.” The phrase is specifically talking about the presence of honey in hummingbirds’ stomachs, not of insects, so we can eliminate the answer choice “Hummingbirds can be found with insects in their stomachs, but this is rare.” Since “not generally” means “not most of the time,” the author is saying “sometimes, but not most of the time, hummingbirds have honey in their stomachs.” This is only accurately stated by the answer choice “Hummingbirds can be found with honey in their stomachs, but it is not common.” The answer choices “Hummingbirds can be found with both honey and insects in their stomachs, and this is what scientists observe most often” and “Hummingbirds can be found with only honey in their stomachs quite often” are incorrect because neither suggests that finding a hummingbird with honey in its stomach is rare, which is what the author is saying.

Example Question #1 : Making Inferences About The Author Or Natural Science Passage Content

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.”

Based on what is said in the passage, the author most likely believes that __________.

Possible Answers:

hummingbirds eat neither flower nectar nor insects

hummingbirds eat a mixture of flower nectar and insects, but mostly insects

None of the other answers

hummingbirds eat only flower nectar

hummingbirds eat a mixture of flower nectar and insects, but mostly flower nectar

Correct answer:

hummingbirds eat a mixture of flower nectar and insects, but mostly insects

Explanation:

This is a tricky question because in the passage, the author never directly states his opinion about what hummingbirds eat; readers have to infer it based on the evidence he presents. The author begins the passage by stating that while old scientists used to think hummingbirds ate only flower nectar, modern writers think that they eat “largely, and in some cases wholly,” on insects. He then presents evidence suggesting that hummingbirds eat insects, and in discussing the contents of hummingbirds’ stomachs, says that scientists sometimes find both insects and honey. For the rest of the paragraph, he provides evidence suggesting that hummingbirds eat insects.

What can we infer from this? Well, we can tell that it’s not likely that the author thinks hummingbirds eat only flower nectar, because he provides evidence supporting the idea that they eat insects. This means that we can also discard the answer choice “hummingbirds eat neither flower nectar nor insects.” It’s quite reasonable to think that the author thinks that “hummingbirds eat a mixture of flower nectar and insects” because he mentions that sometimes honey is found along with insects in hummingbirds’ stomachs. So, we need to figure out whether he probably believes that they eat mostly insects or mostly flower nectar. Let’s look at how the author phrases his description of the contents of hummingbirds’ stomachs: “in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey.” So, if “in almost every instance” the hummingbird stomachs examined were “full of insects,” but “sometimes, but not generally” honey was also found, the correct answer must be “hummingbirds eat a mixture of flower nectar and insects, but mostly insects.”

Example Question #11 : Inferences And Predictions In Narrative 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 inferences does the passage expect its readers to make?

Possible Answers:

Fly-catchers are a type of insect.

If a hummingbird eats gnats, it will not eat honey.

If a hummingbird consumes flower nectar, this nectar will turn into the honey that can be found in its stomach.

The author is the first scientist to ever have investigated what hummingbirds eat.

Scientists rarely learn about hummingbirds by dissecting them.

Correct answer:

If a hummingbird consumes flower nectar, this nectar will turn into the honey that can be found in its stomach.

Explanation:

Let’s consider each of the answer choices to identify the correct one.

“The author is the first scientist to ever have investigated what hummingbirds eat.” - This cannot be true, because the author begins the passage by saying “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.” He also cites numerous other scientists’ opinions throughout the passage, so he can’t be the first person to have investigated what hummingbirds eat.

“Fly-catchers are a type of insect.” - The passage mentions fly-catchers in the following sentence: “Many [hummingbirds] 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.” This is a tricky answer choice in that it’s easy to misread the sentence and think that “just like flycatchers” refers to “other small insects” when in fact it refers to the act of “catching.” The sentence is saying that hummingbirds catch insects in the same manner as fly-catchers, not that fly-catchers are a type of insect. Plus, we are being asked to identify an inference readers are expected to make, and if this sentence did mean that fly-catchers were insects, it would be overtly telling us this, and there would be nothing we’d have to infer.

“Scientists rarely learn about hummingbirds by dissecting them.” - This answer choice is proven wrong by the following sentence: “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.”

“If a hummingbird eats gnats, it will not eat honey.” - Given that the questions of whether hummingbirds eat insects or honey and in what proportions is the topic of the passage, it may be easy to choose this answer choice because it seems like the one closest to the passage’s main idea; however, nothing in the passage supports this assertion.

“If a hummingbird consumes flower nectar, this nectar will turn into the honey that can be found in its stomach.” - This is the correct answer! The author initially states that “All the early writers down to Buffon believed that [hummingbirds] lived solely on the nectar of flowers”; however, he later states that “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.” The author does not address the idea that flower nectar and honey could be different substances, and instead expects the reader to treat these as one source of food.

Example Question #1 : Extrapolating From The Text In 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.”

Based on the way the term is used in passage, what is “the Polytmus”?

Possible Answers:

A type of hummingbird with a long tail

A scientific term for a fledgling hummingbird that cannot yet fly

A type of carnivorous mammal that eats hummingbirds

A type of hummingbird with particularly bright coloring

A species of flower that often attracts hummingbirds

Correct answer:

A type of hummingbird with a long tail

Explanation:

Let’s look at the spot in the passage where “the Polytmus” is mentioned: 

“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.’” 

From this context, we can tell that the Polytmus isn’t a carnivorous hummingbird-eating mammal, or a species of flower: it is a hummingbird. It is mentioned in the context of flying, so it can’t refer to a fledgling hummingbird that can’t yet fly. So, is it mentioning a type of hummingbird with particularly bright coloring, or one with a long tail? Mr. Gosse mentions the Polytmus in particular because observers can easily see it contort in midair “from the effect that such motions have on the long feathers of the tail.” So, the Polytmus must be “a type of hummingbird with a long tail.”

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