GMAT Reading Comprehension passages belonging to the natural science/research category make for great attentive reading practice. They usually feature a level of technical information crucial to understanding the passage, but they often also involve a clash between findings, theories, or viewpoints. This forces the reader to give due attention to all three “tracks” of information. As a refresher, here are the three tracks introduced in an earlier article in this series:

what the passage says  |  what the author is doing  |  what the author/subjects think

Tips for GMAT Reading comprehension: Natural science/research passages

Natural science/research passages almost always feature some phenomenon, process, or interaction between variables that force careful attention to track 1. You have to understand the technicalities in order to make sense of the passage.

But you must also move past the science to the viewpoints of the scientists/researchers, especially when there are multiple viewpoints that conflict or compete. The passage below from the Official Guide is a perfect example for our purposes. As you read, use the three-track strategy to take brief notes.

(1)     There are recent reports of apparently drastic

         declines in amphibian populations and of extinctions

         of a number of the world’s endangered amphibian

         species. These declines, if real, may be signs of a

(5)     general trend toward extinction, and many

         environmentalists have claimed that immediate

         environmental action is necessary to remedy

         this “amphibian crisis,” which, in their view, is an

         indicator of general and catastrophic environmental

(10)   degradation due to human activity.

         To evaluate these claims, it is useful to make a

         preliminary distinction that is far too often ignored.

         A declining population should not be confused with

         an endangered one. An endangered population is

(15)   always rare, almost always small, and, by definition,

         under constant threat of extinction even without a

         proximate cause in human activities. Its disappearance,

         however unfortunate, should come as no great

         surprise. Moreover, chance events – which may

(20)   indicate nothing about the direction of trends in

         population size – may lead to its extinction. The

         probability of extinction due to such random factors

         depends on the population size and is independent of

         the prevailing direction of change in that size.

(25)   For biologists, population declines are potentially

         more worrisome than extinctions. Persistent

         declines, especially in large populations, indicate a

         changed ecological context. Even here, distinctions

         must again be made among declines that are only

(30)   apparent (in the sense that they are part of habitual

         cycles or of normal fluctuations), declines that take

         a population to some lower but still acceptable

         level, and those that threaten extinction (e.g., by

         taking the number of individuals below the minimum

(35)   viable population). Anecdotal reports of population

         decreases cannot distinguish among these

         possibilities, and some amphibian populations have

         shown strong fluctuations in the past.

         It is indisputably true that there is simply not

(40)   enough long-term scientific data on amphibian

         populations to enable researchers to identify real

         declines in amphibian populations. Many fairly

         common amphibian species declared all but extinct

         after several declines in the 1950s and 1960s

(45)   have subsequently recovered, and so might

         the apparently declining populations that have

         generated the current appearance of an amphibian

         crisis. Unfortunately, long-term data will not soon

         be forthcoming, and postponing environmental

(50)   action while we wait for it may doom species and

         whole ecosystems to extinction.

In the very first line, the word “apparently” should trigger your track 3 alarm. Is this simply principled scientific caution to avoid overstating the findings? Or does the author question the accuracy or validity of the reports?

We don’t have to wait long to find out, since the author uses the phrase “if real” in line 4 in reference to the reported declines. In line 8, the author further distances herself from “many environmentalists” (line 5) by using the phrase, “in their view.” We have a scientific disagreement, and our track 3 attention is firing on all cylinders. The author apparently disagrees with the assessment of “many environmentalists” that the “amphibian crisis” – if such a crisis even exists – is an indicator of general and catastrophic environmental degradation due to human activity.

GMAT Reading Comprehension: Three-track Thinking

At the end of the first paragraph, your three tracks thinking may look something like this:

  • Track 1: There may be an “amphibian crisis” involving both population declines and extinctions of endangered amphibian species.
  • Track 2: The author is calling into question the reports and conclusions of many environmentalists surrounding the “amphibian crisis.”
  • Track 3: The subjects believe that the “amphibian crisis” is real and that it indicates serious environmental degradation due to human activity. The author disagrees.

The time limit of the GMAT Verbal Reasoning section won’t allow you to write notes like these, but you should take a moment to make mental notes along these lines. When the author of a passage so openly takes issue with another viewpoint, tracks 2 and 3 tend to converge.

You shouldn’t overinvest your time on the second paragraph. We can summarize it by thinking in terms of track 2.  First, the author distinguishes between declining populations and endangered populations, implying that the failure to draw such a distinction is a problem behind the way many environmentalists have responded to the supposed “amphibian crisis.”  Then, the author gives her definition of an endangered population in lines 14-17. The line numbers of this definition are something you should actually write down for future reference.

As a general rule, give extra attention whenever an author defines a term, and write down the line numbers of the definition. In this case, a feature of the definition of “endangered” is key to the author’s argument. Per the author, endangered species are “under constant threat of extinction even without a proximate cause in human activities.” What is the author doing? She is decoupling human activity and the reported extinctions of endangered amphibian species.

If the extinction of an endangered species cannot be reliably attributed to human activity, then the extinction of endangered amphibian species cannot reliably indicate serious environmental degradation due to human activity. 

After thinking through what the author did in the second paragraph, it should become evident that she is systematically attacking the reports mentioned in the first sentence of the passage. Here’s that sentence:

There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world’s endangered amphibian species.

When you first read this sentence, you may not have even noticed that these “recent reports” are twofold. It is easy to conflate “drastic (amphibian) population declines” and “extinctions of endangered (amphibian) species.” But after reading the second paragraph, where the author dealt with the reports of extinctions of endangered species; we should expect her to turn next to the reports of drastic population declines. And this is exactly what she does in the third paragraph.

We should notice the reuse of the word “distinctions” in line 28. As in the second paragraph, the author proceeds by drawing distinctions and defining the kind of population decline that would indicate a “changed ecological context:” a persistent decline, especially in a large population. The final sentence of the paragraph makes the point that “anecdotal reports of population decreases,” that is, the reports mentioned at the beginning of the passage, cannot distinguish the worrisome population decreases from the innocuous ones

We haven’t made many track 1 notes, and that’s okay. The second and third paragraphs haven’t laid out any scientific data; they have been about the author’s definitions and distinctions, and how those definitions and distinctions, in the author’s view, invalidate many environmentalist’s conclusions about human activities’ causation of the amphibian crisis. You might have some track 3 notes about the definitions and distinctions drawn by the author and some general track 2 notes about how the second and third paragraphs deal with extinctions and population declines, respectively.

Moving into the fourth paragraph, the author’s argument is rather direct: we don’t have the long-term data to identify “real” amphibian population declines. Then she refers to an amphibian population decline-and-recovery dating to the 1950s and 1960s. We should be expecting a Function/plan question based on this reference. 

Now here is the final sentence of the passage:

Unfortunately, long-term data will not soon be forthcoming, and postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.

This is a real twist ending. If you were paying attention when you first read this, your mind should have done something like a double take. The author spent the entire passage invalidating the argument of many environmentalists that there is an amphibian crisis which indicates environmental fallout from human activity, and we might have assumed that she would end the passage by saying something like, “Quit worrying about the frogs and get back to pumping your gasoline.”

But the final sentence carries a completely different implication! In the author’s view, even though the evidence surrounding the supposed amphibian crisis is inconclusive, the potential consequences of postponing environmental action are too serious to ignore. (I’m reasonably confident that this is the only occurrence of the word “doom” in a GMAT Reading Comprehension passage.) The amphibian crisis jury is out, yet we must act now. We are left wondering why the author bothered writing this passage at all. Have you ever invalidated someone’s argument just to agree with their proposals?

GMAT Reading Comprehension Practice Question

On that note, here’s the main idea question:

The primary purpose of the passage is to

(A) assess the validity of a certain view

(B) distinguish between two phenomena

(C) identify the causes of a problem

(D) describe a disturbing trend

(E) allay concern about a particular phenomenon

If you completely miss the implication of the passage’s final sentence, answer choice E looks great. If you noticed the final sentence, you have to go with answer choice A.

The author drew some distinctions, but distinguishing between phenomena (choice B) was not the primary concern of the passage. Choices C and D can be thrown out because the author is not ready to concede that there is a problem or a disturbing trend. Choice A is correct. Always give special attention to the final sentence of a passage.

GMAT Reading Comprehension Practice Question

It can be inferred from the passage that the author believes which of the following to be true of the environmentalists mentioned in lines 5-6?

(A) They have wrongly chosen to focus on anecdotal reports rather than on the long-term data that are currently available concerning amphibians.

(B) Their recommendations are flawed because their research focuses too narrowly on a single category of animal species.

(C) Their certainty that population declines in general are caused by environmental degradation is not warranted.

(D) They have drawn premature conclusions concerning a crisis in amphibian populations from recent reports of declines.

(E) They have overestimated the effects of chance events on trends in amphibian populations.

Let’s take the answer choices one by one.

Choice A seems to be going the right direction, but it says that long-term data concerning amphibians are “currently available.” (The construction “data are” is correct; “data” can be singular or plural.) We know from the last paragraph that such long-term data is not currently available.

Choice B is out; the author doesn’t criticize the environmentalists’ focus on amphibians as too narrow. Also, no recommendations from the environmentalists are given, and if they were, the passage’s last sentence should lead us to believe that the author would actually agree with them.

Choice C might look attractive, but the environmentalists never claim to be certain that population declines in general are caused by environmental degradation. We only know that they attribute the amphibian crisis to “general and catastrophic environmental degradation.” Choice C tries to trick you by using the word “general,” but it applies the word differently than the passage did. Beware of such answer choices.

Choice D looks great, and choice E refers to a detail mentioned in the second paragraph. The only real problem with choice E is that it says “overestimated” instead of “underestimated.” Choice D is correct.

GMAT Reading Comprehension Practice Question

It can be inferred from the passage that the author believes which of the following to be true of the amphibian extinctions that have recently been reported?

(A) They have resulted primarily from human activities causing environmental degradation.

(B) They could probably have been prevented if timely action had been taken to protect the habitats of amphibian species.

(C) They should not come as a surprise, because amphibian populations generally have been declining for a number of years.

(D) They have probably been caused by a combination of chance events.

(E) They do not clearly constitute evidence of general environmental degradation.

Another author views question. You should know that the second paragraph is your point of reference for this question.

Choices A and B should be dismissed as views contrary to those of the author.

Choice C looks good at first, but we don’t know whether amphibian populations generally have been declining for a number of years.

I think choice D is the most attractive incorrect answer. It is too much of a logical leap. The author does say that chance events can cause extinctions, but he does not go so far as to assert that such chance events have caused the reported amphibian extinctions.

Correct answer choice E is much safer; it follows much more directly from the explicit statements of the author in the second paragraph. She aims not to explain the extinctions but to invalidate the conclusions others have drawn from them by pointing out that alternative explanations exist. 

GMAT Reading Comprehension Practice Question

According to the passage, each of the following is true of endangered amphibian species EXCEPT:

(A) They are among the rarest kinds of amphibians.

(B) They generally have populations that are small in size.

(C) They are in constant danger of extinction.

(D) Those with decreasing populations are the most likely candidates for immediate extinction.

(E) They are in danger of extinction due to events that sometimes have nothing to do with human activities.

“Except” questions, like many RC questions, should be approached with an “elimination first” strategy. Again, the second paragraph is your point of reference. Choices A, B C, and E can all be eliminated by a single sentence from that paragraph!

An endangered population is always rare, almost always small, and, by definition, under constant threat of extinction even without a proximate cause in human activities.

Once you read this sentence, you don’t even have to think about answer choice D. If you’re curious, refer to the last sentence of the second paragraph, which choice D directly contradicts.

GMAT Reading Comprehension Practice Question

Which of the following most accurately describes the organization of the passage?

(A) A question is raised, a distinction regarding it is made, and the question is answered.

(B) An interpretation is presented, its soundness is examined, and a warning is given.

(C) A situation is described, its consequences are analyzed, and a prediction is made.

(D) Two interpretations of a phenomenon are described, and one of them is rejected as invalid.

(E) Two methods for analyzing a phenomenon are compared, and further study of the phenomenon is recommended.

We’ve talked so much about what the author is doing in this passage that, hopefully, answer choice B leaps off the page here. The passage doesn’t answer the question raised in the first paragraph (choice A), it doesn’t end with a prediction (choice C), and it doesn’t deal with two interpretations or methods of analysis (choices D and E).

GMAT Reading Comprehension Practice Question

Which of the following best describes the function of the sentence in lines 35-38?

(A) To give an example of a particular kind of study

(B) To cast doubt on an assertion made in the previous sentence

(C) To raise an objection to a view presented in the first paragraph

(D) To provide support for a view presented in the first paragraph

(E) To introduce an idea that will be countered in the following paragraph

To spare you the scrolling, here’s the sentence:

Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past.

I predicted a Function/role question on the “1950s and 1960s” reference in the final paragraph, a prediction that turned out to be just a bit off.  Again, since we’ve analyzed this passage ad nauseam, answer choice C should leap off the page.

It feels almost too general and predictable, but all the other answer choices have problems. It’s not an example (choice A). The author certainly doesn’t want to cast doubt on her own assertions (choice B). She definitely doesn’t want to support the view presented in the first paragraph (choice D). And she definitely doesn’t counter this idea in the final paragraph (choice E).

When reading natural science/research passages on the GMAT, make sure you understand the technicalities of the scientific topic. In this passage, it’s the definition of “endangered” and the kind of population decline that indicates a changed ecological context, all according to the author. And as far as these technicalities give rise to conflicting or competing views among scientists, understand who believes what, and why they believe it. You’ll be well on your way to answering any questions connected to the passage.

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Contributor: Elijah Mize (Apex GMAT Instructor)

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