Just as paleontologists claim that ecologists' findings about the

Question

﻿Just as paleontologists claim that ecologists' findings about the evolution and extinction of species help eliminate discontinuities in the history of life on Earth, ecologists have recently found that paleontology aids in predicting the effects of rapid climate change and habitat destruction. For example, one paleontological study, in which pollen found in lake sediments was analyzed to determine how North American forests responded to the last ice age, supports one side of a debate over the stability of "ecological communities," or species that evolved in proximity to each other and with some degree of interdependence. Pro-stability ecologists believe that such communities are quite stable due to strong interdependence so that, for example, tree species that evolve together as a community can be expected to remain together since each significantly affects immediate environmental factors such as soil chemistry and shade. But while the pollen study did indicate that advancing glaciers caused the gradual relocation of three tree species-birch, fir, and spruce-that had comprised one community, it also supported the assumption of anti-stability proponents that the three species did not, after all, move together as would the inhabitants of a town resettling en masse on higher ground during flooding. Instead, the spruce trees began to share an ecosystem with sedge grasses, becoming part of an entirely different community.   1 
 ﻿1. The passage is primarily concerned with

A. demonstrating that paleontologists have made important contributions to the study of the effects of habitat destruction during the last ice age
B. countering the theory that species in ecological communities are stable and interdependent
C. analyzing the reasons for the debate about the interdependence of species in ecological communities
D. presenting an example of how the findings of paleontologists can illuminate questions in the field of ecology
E. tracing the effects of rapid climate change on a given ecological community of tree species

2 
 2. It can be inferred from the passage that the proponents of the anti-stability view of ecological communities would be likely to agree with which of the following statements?

A. Since future climate changes are expected to be rapid, there is little reason to try to predict their effects on the basis of the effects of past climate changes.
B. Although an ecological community includes species that evolved in association with each other, changes in the environment can alter the degree of their interdependence.
C. When the species of trees belonging to a single ecological community are forced to relocate, those species will lose their interdependence gradually.
D. At the onset of the last ice age, birches and firs did not provide the optimum shade or soil composition for spruces.
E. At the onset of the last ice age, neither birches nor firs were compatible with sedge grasses.

3 ﻿
 3. The author of the passage implies that the findings of the pollen study are likely to

A. cause pro-stability ecologists to redefine an ecological community as a group of species that are in constant, although gradual, migration
B. help paleontologists answer long-standing questions about the effect of tree communities on soil chemistry
C. help ecologists predict the possible effects of climate changes on ecological communities of tree species
D. support the assertion of pro-stability ecologists that ecological communities remain intact when forced by climate change to relocate
E. persuade anti-stability ecologists to reject paleontological evidence in evaluating their assumptions about ecological communities

MartyMurray · Accepted Answer

Explanation for Question 1

﻿1. The passage is primarily concerned with

A. demonstrating that paleontologists have made important contributions to the study of the effects of habitat destruction during the last ice age

Notice that this choice is about "contributions to the study of the effects of habitat destruction during the last ice age," an event in the PAST.

Let's review the passage to see whether the purpose is to show how paleontologists have contributed to "the study of the effects of habitat destruction during the last ice age."

The main point of the passage is expressed by this statement:

ecologists have recently found that paleontology aids in predicting the effects of rapid climate change and habitat destruction

Then, everything that follows that statement composes an example that supports that statement: "For example, one paleontological study, in which pollen found in lake sediments was analyzed to determine how North American forests responded to the last ice age, supports one side of a debate."

So, the purpose of the passage is not to demonstrate how paleontologists have contributed to ""the study of the effects of habitat destruction during the last ice age," which is a past event that paleontologists have studied. Rather the purpose of the passage is to demonstrate how paleontologists have contributed to ECOLOGISTS' understanding of the effects of habitat destruction and "predicting" effects in the FUTURE, rather than the past.

Also, this choice has another failure point in that the passage does not mention "habitat destruction during the last ice age." Rather, it mentions "advancing glaciers."

Eliminate.

B. countering the theory that species in ecological communities are stable and interdependent

This choice is tricky, because the passage says that the pollen study "supported the assumption of anti-stability proponents."

Notice, however, that the information provided does not counter the idea that "species" are stable or that species are interdependent. Rather, the pollen study information indicates only that "communities" may not be as stable as pro-stability ecologists believe them to be even though species are interdependent.

Also, there's another issue with this choice in that the passage is not primarily concerned with countering any particular idea. Rather, it's concerned with the more general idea that "ecologists have recently found that paleontology aids in predicting the effects of rapid climate change and habitat destruction."

Eliminate.

C. analyzing the reasons for the debate about the interdependence of species in ecological communities

The passage does not analyze, or even mention, any "reasons for the debate about the interdependence of species in ecological communities."

Eliminate.

D. presenting an example of how the findings of paleontologists can illuminate questions in the field of ecology

This choice accurately captures what the passage is primarily concerned with.

The passage begins by stating a point about how "ecologists have recently found that paleontology aids" their work. Then it presents an extended example of how "the findings of paleontologists," the findings of the pollen study, supported "one side of a debate" among ecologists and thus "illuminate" a question ecologists have had.

Keep.

E. tracing the effects of rapid climate change on a given ecological community of tree species

The passage mentions one effect of "advancing glaciers" on "a given ecological community of tree species," but this choice fails in multiple ways.

For one thing, "advancing glaciers" is not "rapid climate change." Rather, the passage mentions "advancing glaciers caused the  gradual  relocation," indicating that the change was gradual.

Meanwhile, there's a larger issue in that the mention of effects of the advancing glaciers is only a small portion of the passage. The passage overall is not concerned with "tracing the effects." Rather, those effects are mentioned in the context of providing an example of how the work of paleontologists helps ecologists.

Eliminate.

The correct answer is (D).

Explanation for Question 2

2. It can be inferred from the passage that the proponents of the anti-stability view of ecological communities would be likely to agree with which of the following statements?

A. Since future climate changes are expected to be rapid, there is little reason to try to predict their effects on the basis of the effects of past climate changes.

This choice is basically contrary to what the passage says. The passage says that ecologists in general, including "proponents of the anti-stability view," find that the work of paleontologists helps them to make predictions.

Also, the passage says that paleontologists' work supports the position of the proponents of the anti-stability view and thus implies that they would agree that considering the effects of past climate changes would be helpful.

Eliminate.

B. Although an ecological community includes species that evolved in association with each other, changes in the environment can alter the degree of their interdependence.

The passage says the following:

But while the pollen study did indicate that advancing glaciers caused the gradual relocation of three tree species-birch, fir, and spruce-that had comprised one community, it also supported the assumption of anti-stability proponents that the three species did not, after all, move together as would the inhabitants of a town resettling en masse on higher ground during flooding. Instead, the spruce trees began to share an ecosystem with sedge grasses, becoming part of an entirely different community

We see that the position of anti-stability proponents that was supported by the pollen study involved three tree species that had evolved together as a community not remaining as interdependent as they had been, with one species, spruce, becoming part of a different community.

That position matches this choice in that it involves species that "evolved in association with each other" and altered "the degree of their interdependence" in response to "changes in the environment."

Keep

C. When the species of trees belonging to a single ecological community are forced to relocate, those species will lose their interdependence gradually.

This choice is tricky to eliminate because it seems to match what the proponents of the anti-stability view believe but it fails in a couple ways.

One is that the passage doesn't say that the proponents of the anti-stability view believe that species of trees will that are forced to relocate will necessarily lose their interdependence. In fact, in the example provided, only one species, spruce, is said to have become less interdependent. So, the other two species, birch and fir, may have remained interdependent.

The other is that the passage never says that the proponents of the anti-stability view believe that species will lose their interdependence "gradually." The rate at which the species are believed to lose their interdependence is not discussed.

Eliminate.

D. At the onset of the last ice age, birches and firs did not provide the optimum shade or soil composition for spruces.

The passage indicates that, before the last ice age, birches, firs, and spruces were interdependent. It was only after the ice age began that they became less interdependent.

So, there's no reason to believe that the proponents of the anti-stability view would have believed that at the onset (beginning) of the ice age, birches and firs did not provide the optimum shade or soil composition for spruces. Rather, any ecologist would likely agree that the species were interdependent for some reason, which could have been that birches and firs DID provide the optimum shade or soil composition for spruces.

Eliminate.

E. At the onset of the last ice age, neither birches nor firs were compatible with sedge grasses.

The passage says the following about "sedge grasses" in the context of discussing the position of the proponents of the anti-stability view:

the spruce trees began to share an ecosystem with sedge grasses, becoming part of an entirely different community

So, the only thing said about sedge grasses in the context of the position of the proponents of the anti-stability view indicates that spruce trees were compatible with sedge grasses. Nothing said involves birches and firs not being compatible with sedge grasses.

Eliminate.

The correct answer is (B).

Explanation for Question 3 
﻿
  3. The author of the passage implies that the findings of the pollen study are likely to

A. cause pro-stability ecologists to redefine an ecological community as a group of species that are in constant, although gradual, migration

The findings of the pollen study are about the migration of an ecological community. At the same time, they don't indicate that every ecological community is "in constant migration."

After all, the fact that one community migrated in response to advancing glaciers doesn't mean that all communities are in constant migration.

Eliminate.

B. help paleontologists answer long-standing questions about the effect of tree communities on soil chemistry

The mentioned findings of the pollen study do not involve any thing specific related to effects on soil chemistry.

Eliminate.

C. help ecologists predict the possible effects of climate changes on ecological communities of tree species

The author says the following:

ecologists have recently found that  paleontology aids in predicting the effects of rapid climate change  and habitat destruction.  For example, one paleontological study, in which pollen found in lake sediments was analyzed  to determine how North American forests responded to the last ice age, supports one side of a debate over the stability of "ecological communities,"

We see that the author uses the pollen study, which involves an ecological community of tree species, as an "example" of how "paleontology aids in predicting the effects of rapid climate change."

Thus, the author is implying that the findings of the pollen study are likely to "help ecologists predict the possible effects of climate changes on ecological communities of tree species."

Keep.

D. support the assertion of pro-stability ecologists that ecological communities remain intact when forced by climate change to relocate

This is the opposite of what the passage says. The passage says the following about the pollen study:

it also supported the assumption of anti-stability proponents that the three species  did not, after all, move together  as would the inhabitants of a town resettling en masse on higher ground during flooding

Eliminate.

E. persuade anti-stability ecologists to reject paleontological evidence in evaluating their assumptions about ecological communities

The passage says the following about the findings of the pollen study, which involved "paleontological evidence":

it also supported the assumption of anti-stability proponents

We see that the findings of the study supported the position of anti-stability ecologists. So, those findings would not likely cause those ecologists to "reject paleontological evidence" since there is no reason to believe they would reject what supports their position.

Eliminate.

The correct answer is (C).

MartyMurray · Answer

Here's the question:

The passage is primarily concerned with

Now, let's consider choice (A).

demonstrating that paleontologists have made important contributions to the study of the effects of habitat destruction during the last ice age

Notice that this choice is about "contributions to the study of the effects of habitat destruction during the last ice age," an event in the PAST.

Let's review the passage to see whether the purpose is to show how paleontologists have contributed to "the study of the effects of habitat destruction during the last ice age."

The main point of the passage is expressed by this statement:

ecologists have recently found that paleontology aids in predicting the effects of rapid climate change and habitat destruction.

Then, everything that follows that statement composes an example that supports that statement: " For example, one paleontological study, in which pollen found in lake sediments was analyzed to determine how North American forests responded to the last ice age, supports one side of a debate. "

So, the purpose of the passage is not to demonstrate how paleontologists have contributed to ""the study of the effects of habitat destruction during the last ice age," which is a past event that paleontologists have studied. Rather the purpose of the passage is to demonstrate how paleontologists have contributed to ECOLOGISTS' understanding of the effects of habitat destruction and "predicting" effects in the FUTURE, rather than the past.

Also, choice (A) has another failure point in that the passage does not mention "habitat destruction during the last ice age." Rather, it mentions "advancing glaciers."

So, choice (A) fails in these two ways to capture the primary purpose of the passage.

Now, let's consider choice (D).

presenting an example of how the findings of paleontologists can illuminate questions in the field of ecology

As we have seen in our review of the passage, this choice accurately captures what the passage is primarily concerned with.

The passage begins by stating a point about how "ecologists have recently found that paleontology aids" their work. Then it presents an extended example of how "the findings of paleontologists" supported "one side of a debate" among ecologists and thus "illuminate" a question ecologists have had.

So, we can see that the correct answer is (D).

mustafa87 · Answer

GMATninja, KarishmaBansal

For the first question of this passage, I am unable to decide between answer choices A and D. You have mentioned in your previous posts/blogs, several times, that for 'the main purpose questions' is to look for why the author has written this passage. The way the answers choices A and D are framed are both appealing choices.

Answer choice A, does cover the first 5 lines of the passage, and then goes on to address how the Paleontologists have helped the Ecologists work with the demonstration of an example.

Please illuminate (no pun intended) on how D is a better choice than A.

Sonia2023 · Answer

2. It can be inferred from the passage that the proponents of the anti-stability view of ecological communities would be likely to agree with which of the following statements?

A. Since future climate changes are expected to be rapid, there is little reason to try to predict their effects on the basis of the effects of past climate changes.
B. Although an ecological community includes species that evolved in association with each other, changes in the environment can alter the degree of their interdependence.
C. When the species of trees belonging to a single ecological community are forced to relocate, those species will lose their interdependence gradually.
D. At the onset of the last ice age, birches and firs did not provide the optimum shade or soil composition for spruces.
E. At the onset of the last ice age, neither birches nor firs were compatible with sedge grasses.

﻿ AjiteshArun   KarishmaB   egmat  - Can you please explain Question 2 - Choice B and C?

Here is what I thought while answering the question:

It can be inferred from the passage that the proponents of the anti-stability view of ecological communities would be likely to agree with which of the following statements?

Reason for rejecting choice C: 
 
 When the species of trees belonging to a single ecological community are forced to relocate, those species will lose their interdependence gradually.

It introduces a conditional statement that whenever species of trees belonging to a single ecological community are forced to relocate, those species will lose their interdependence. But from no where in the passage, this explicit relationship can be inferred. We don't know whether Anti stability ecologists will  likely  agree to this. Moreover, trees are just example of ecological communities.

Reason for selecting choice B over C:
 Although an ecological community includes species that evolved in association with each other, changes in the environment can alter the degree of their interdependence.

Support from the passage: 
 Although an ecological community includes species that evolved in association with each other  -->  Excerpt from the passage: "ecological communities," or species that evolved in proximity to each other and with some degree of interdependence.
  -  This is just the definition of the ecological community so they ought to believe it.

Changes in the environment can alter the degree of their interdependence --->

Pro-stability ecologists believe that such communities are quite stable due to strong interdependence -  it can be inferred that Anti-stability would at minimum believe that such communities are not that stable as what pro believe. 
  
But while the pollen study did indicate that advancing glaciers caused the gradual relocation of three tree species-birch, fir, and spruce-that had comprised one community, it also supported the  assumption  of anti-stability proponents that the three species did not, after all, move together as would the inhabitants of a town resettling en masse on higher ground during flooding.  Instead, the spruce trees began to share an ecosystem with sedge grasses, becoming part of an entirely different community  .

Does this make sense?

Thank you

KarishmaB · Answer

My only problem with option (C) is the use of the word 'gradually.' The rate of reduction in interdependence is not discussed. It is not something we can infer from the passage at all.

I don't know what actually the anti-stability view is - it could be that 'they will lose their interdependence,' or it could be 'they might lose their interdependence' so otherwise I am not sure which option I would pick.

Also, the proponents could agree with a more specific statement about trees or the more generic statement about species - I can't pick based on that either.

FlyPig · Answer

Choose b rather than c

the focus on gradual loss due to relocation alone does not entirely capture the broader perspective of how environmental changes can affect interdependence among species within ecological communities, which is more in line with the beliefs of proponents of the anti-stability view (making statement B a more fitting choice)

Gemmie · Answer

﻿1. The passage is primarily concerned with
D. presenting an example of how the findings of paleontologists can illuminate questions in the field of ecology

Passage summary:

- The passage discusses how paleontology and ecology contribute to understanding life on Earth.

- It gives an example of how paleontological research, specifically a study analyzing pollen in lake sediments, has provided insights into a debate within ecology about the stability of "ecological communities."

- The study mentioned in the passage supports both sides of the debate: while some species did relocate together, others did not, challenging the idea of strong interdependence among species.

2. It can be inferred from the passage that the proponents of the anti-stability view of ecological communities would be likely to agree with which of the following statements?
B. Although an ecological community includes species that evolved in association with each other, changes in the environment can alter the degree of their interdependence.

The anti-stability views that species within an ecological community are not necessarily strongly interdependent and that environmental changes can further reduce this interdependence.

The passage provides an example where, during the last ice age, species that were part of the same ecological community did not relocate together. Specifically, spruce trees ended up in a different ecosystem, suggesting that their interdependence with birch and fir trees was not as strong as the pro-stability view would suggest.

3. The author of the passage implies that the findings of the pollen study are likely to
C. help ecologists predict the possible effects of climate changes on ecological communities of tree species

C seems the best answer since

(1) the study provided insights into how different tree species reacted to climate changes during the last ice age ( while some species relocated together, others did not, suggesting that ecological communities may not always stay intact when environmental conditions change ), which could help ecologists make predictions about future climate effects.

(2) the author also mentions at the beginning that " paleontology aids in predicting the effects of rapid climate change "

VerbalBot · Answer

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Just as paleontologists claim that ecologists' findings about the

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