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Target Test Prep Representative
Joined: 24 Aug 2022
Posts: 45
Given Kudos: 0
GRE 1: Q170 V170
Re: As Gilbert White, Darwin, and others observed long ago, all
[#permalink]
30 Sep 2022, 03:16
30 Sep 2022, 03:16
Expert Reply
Quote:
22. The discussion concerning population in the third paragraph serves primarily to
Primary purpose items most often deal with the passage as a whole (as does the first question in this set), but the same guidelines apply here: The "primary" purpose/function should accurately cover MOST of what's happening (including anything that's clearly presented as a conclusion), but not necessarily every word. Anything unsupported immediately eliminates an answer choice.
Quote:
(A) demonstrate the difficulties ecologists face in studying density-dependent factors limiting population growth
¶3 doesn't mention anything about the practical situations faced by ecological researchers. A hypothetical case is laid out for the purposes of the 99%/1% discussion, but that case remains entirely theoretical. (It's only in ¶4 that there's some mention of the fact that ecologists' ability to substantiate this stuff is limited in certain cases.)
Not supported. Eliminate.
Quote:
(B) advocate more rigorous study of density dependent factors in population growth
This passage does not engage in advocacy (= persuasive writing that argues for one side of an issue and/or against the other).
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(C) prove that the death rates of any population are never entirely density-independent
The easiest way to eliminate this choice is to notice that it isolates "death rates"—a statistic that only appears in ¶3 as one out of a set of three types of statistics (birth rates, death rates, and migration rates).
These three factors are mentioned in identical context, on absolutely equal footing, so it's not possible that just one of the three is somehow "PRIMARY" = more important than the other two!
Quote:
(D) give an example of how death rates function to limit population densities in typical populations
Interestingly, this choice is incorrect for precisely the same reason as the previous one. When three factors are presented in exactly the same context with exactly the same degree of emphasis, all three of them must be accorded the same degree of importance in any discussion, meaning that no one of them can be "primary".
What's more, ¶3 makes no attempt at all to give any actual example of this phenomenon. In fact, the only specific point it makes on that front is to note that, in many cases, those details WON'T be known and will be quite hard to describe.
Quote:
(E) underline the importance of even small density-dependent factors in regulating long-term population densities
Most of ¶3 is dedicated to the principle that the author illustrates using the hypothetical case of a population whose numbers are 99% driven by density-independent factors and 1% driven by density-dependent factors. The point of that illustration is that, for long-term purposes, that 1% will eventually win out and determine the population average—thus underscoring the importance of exactly what is named in this choice.
Correct choice is E.
Target Test Prep Representative
Joined: 24 Aug 2022
Posts: 45
Given Kudos: 0
GRE 1: Q170 V170
Re: As Gilbert White, Darwin, and others observed long ago, all
[#permalink]
30 Sep 2022, 03:23
30 Sep 2022, 03:23
Expert Reply
Quote:
23. In the passage, the author does all of the following EXCEPT
We want the thing that DOESN'T happen in the passage. We can eliminate anything that DOES happen.
Quote:
(A) cite the views of other biologists
This is a biological topic, so "one school of thought" (¶2) represents the collection of views held by a certain set of biological scientists. Eliminate.
Quote:
(B) define a basic problem that the passage addresses
This basic problem directly follows the words "The task for ecologists is..." in ¶1. Eliminate.
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(C) present conceptual categories used by other biologists
According to ¶2, a certain set of biologists—those belonging to the "school of thought" mentioned above under choice A—believe that populations can be divided strictly into those whose populations are driven by density-dependent effects vs. those whose populations are driven by density-independent effects.
These are conceptual categories. Eliminate.
Quote:
(D) describe the results of a particular study
A specific study will have a specific lead author, who will definitely be named, and possibly additional authors. (E.g., "a 2017 study by Smith and colleagues") No such thing is mentioned at any point here, so this is the correct answer.
Quote:
(E) draw a conclusion
The very last sentence ("all populations are regulated by a mixture of density- dependent and density-independent effects in varying proportions") represents a conclusion reached by the author.
It's D.
Re: As Gilbert White, Darwin, and others observed long ago, all
[#permalink]
01 Oct 2022, 23:59
01 Oct 2022, 23:59
1
Carcass. There's a minor typo in the reading passage, but it should be "vital rates" not "vital, rates." Referenced Big Book Test 26 Section 2
