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To determine whether one species blocks another out of an area, one

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Re: To determine whether one species blocks another out of an area, one [#permalink]
mayurmb wrote:
Score(3 out of 4)
Time (12 mins).
Did I took so long to answer the questions?
Passage was quite difficult for me though.

Posted from my mobile device

Hello mayurmb

Yes your time is not that good you should not have been spend more than 9 minutes on this passage ideally. First two questions are hard but the remaining two are with the medium difficulty level.

Good Luck
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Re: To determine whether one species blocks another out of an area, one [#permalink]
MayurB Can you please explain question 3 and 4?
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Re: To determine whether one species blocks another out of an area, one [#permalink]
Piyush785 wrote:
can you please explain me the question number 2 .

it is clearly mentioned in the passage that the identification of the species cannot be done in isolation,rather it should be done with considering the whole ecosytem.
option 2 says that a kind of fish is introduce in other ecosystem .
it meets the above mentioned criteria.

Official Explanation

2. Which of the following hypothetical experiments most clearly exemplifies the method of identifying species' roles that the author considers problematic?

Difficulty Level: 700

Explanation

The "problematic" aspect most likely was that there were two possible explanations of the second example in the passage, not just one. We can go back and confirm that fact. The expression of the problem starts with the word "but" on line 9. "Whether a species hold an exclusive functional place cannot easily be identified by studying a community as an isolated unit." We want an answer choice that exemplifies this problem, so it might conduct a study just within one community when a neighboring community might be relevant, as in the example of the fish. Each of the answer choices matches our expectation in some respects but not all.

Choice (C) hits all the important points, because, just like the fish example in the passage, it involves trying to determine assembly rules in a specific community based on functional similarity of two species.

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Re: To determine whether one species blocks another out of an area, one [#permalink]
Piyush785 wrote:
can you please explain me the question number 2 .

it is clearly mentioned in the passage that the identification of the species cannot be done in isolation,rather it should be done with considering the whole ecosytem.
option 2 says that a kind of fish is introduce in other ecosystem .
it meets the above mentioned criteria.

­Let me try to explain how I approached this one.

Q: Which of the following hypothetical experiments most clearly exemplifies the method of identifying species' roles that the author considers problematic?

Going back to the passage, this is where we understand what's problematic about identifying specifies:
Quote:
But whether a species holds an exclusive functional place cannot easily be identified by studying a community as an isolated unit; local communities are not isolated assemblages and are better thought of as members of a metacommunity of linked smaller ecosystems. Consequently, observing the existence of two functionally similar species in a particular community could reflect that there is room for both species in the assembly or that they really belong to what are mostly distinct, neighboring communities.

The problem is that two functionally similar species could either tell us that both belong to the same ecosystem or they could not. Now let's look at this:
Quote:
This functional similarity could imply mutual exclusivity, but another possibility is that scophtalmus rhombus and solea solea occupy positions in the same community within the lagoon, perhaps because food is abundant or because they are less functionally similar than they appear; another is that they occupy exclusive positions in neighboring communities within that lagoon

Here, we're given an example that we can use to pick out an experiment from the given choices that most resemble it.

A. The weevils in deciduous forest are counted across a series of ecosystems in order to determine whether they are blocking out other beetles.
This says the approach uses sequencing to determine which species blocks out another one, as mentioned at the beginning of the passage:
Quote:
To determine whether one species blocks another out of an area, one approach is to infer assembly rules, which reconstruct the sequence in which species were added to an evolving community

This isn't the problem. For all we know this method works well. So A is out.

B. A species of fish that is dominant in one marine ecosystem is introduced into another marine ecosystem to see whether the species will be dominant there.
You're right about "species cannot be done in isolation,rather it should be done with considering the whole ecosystem.​​​​​​​" but let's take a closer look at what this means. The author is basically saying you cannot isolate a species and have to consider various sub-ecosystems combined. The answer choice on the other hand, says that a species is introduced to another ecosystem. Even then, their dominance persisting in different ecosystems has no relevance here. So B is out.
​​​​​​​
C. Whether one woodpecker blocks another from occupying a particular ecosystem is determined based on the similarity or difference of their prey in that community.
This option points to the problem in the sense it talks about "abundance of food". It's also quite similar to the example cited above. We know that there is an exception cited at the end of the passage where one species appears to belong to another ecosystem just because there is abundance of food in that ecosystem. C seems a good choice.

D.  Study is made to determine average levels of species diversity in communities in a particular type of climate, such as temperate forests.
Irrelevant and out of scope. Nothing about climate changes and diversity is mentioned in the passage as the problem. D is out.
​​​​​​​
E. Patterns of species extinction are studied in order to evaluate the effect of the climate changes on diversity in a particular tundra community.
Irrelevant and out of scope. Nothing about climate changes is mentioned in the passage as the problem.
E is out.

Therefore, C seems the only correct choice.
­
Re: To determine whether one species blocks another out of an area, one [#permalink]
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