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Many birds that form flocks compete through aggressive interaction for

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Many birds that form flocks compete through aggressive interaction for  [#permalink]

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New post 07 Oct 2019, 09:52
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New Project RC Butler 2019 - Practice 2 RC Passages Everyday
Passage # 375, Date : 07-Oct-2019
This post is a part of New Project RC Butler 2019. Click here for Details


Many birds that form flocks compete through
aggressive interaction for priority of access to
resources such as food and shelter. The result of
repeated interactions between flock members is that
(5) each bird gains a particular social status related to its
fighting ability, with priority of access to resources
increasing with higher status. As the number and
intensity of interactions between birds increase,
however, so increase the costs to each birds in terms of
(10) energy expenditure, time, and risk of injury. Thus,
birds possessing attributes that reduce the number of
costly interactions in which they must be involved,
without leading to a reduction in status, are at an
advantage. An external signal, such as a plumage type,
(15) announcing fighting ability and thereby obviating the
actual need to fight, could be one such attribute.

The zoologist Rohwer assented that plumage
variations in “Harris sparrows” support the status
signaling hypothesis (SSH). He reported that almost
(20) without exception birds with darker throats win
conflicts with individuals having lighter plumage. He
claimed that even among birds of the same age and sex
the amount of dark plumage predicts relative
dominance status.

(25) However, Rohwer’s data do not support his
assertions: in one of his studies darker birds won only
57 out of 75 conflicts; within another, focusing on
conflicts between birds of the same age group or sex,
darker birds won 63 and lost 62. There are indications
(30) that plumage probably does signal broad age-related
differences in status among Harris sparrows: adults,
usually dark throated, have higher status than juveniles,
who are usually light throated; moreover, juveniles
dyed to resemble adults are dominant over undyed
(35) juveniles. However, the Harris sparrows’ age-related
plumage differences do not signal the status of
individual birds within an age class, and thus cannot
properly be included under the term “status signaling.”

The best evidence for status signaling is from the
(40) greater titmouse. Experiments show a strong
correlation between the width of the black breast
plumage stripe and status as measured by success in
aggressive interactions. An analysis of factors likely to
be associated with breast-stripe width (sex, age, wing
(45) length, body weight) has demonstrated social status to
be the only variable that correlates with stripe width
when the other variables are held constant.

An ingenious experiment provided further evidence
for status signaling in the greater titmouse. One of
(50) three stuffed titmouse dummies was mounted on a
feeding tray. When a live bird approached, the dummy
was turned by radio control to face the bird and present
its breast stripe in “display.” When presented with a
dummy having a narrower breast stripe than their own,
(55) birds approached closely and behaved aggressively.
However, when presented with a dummy having a
broader breast stripe than their own, live birds acted
submissive and did not approach.


1. According to the passage, the status signaling hypothesis holds that the ability to display a recognizable external signal would have the effect on an individual bird of

(A) enabling it to attract a mate of high status
(B) allowing it to avoid costly aggressive interactions
(C) decreasing its access to limited resources
(D) making it less attractive to predatory species
(E) increasing its fighting ability



2. The author refers to the fact that adult Harris sparrows are usually dark throated (lines 31-32), in order to do which one of the following?

(A) support the conclusion that plumage variation among Harris sparrows probably does not signal individual status
(B) argue that plumage variation among Harris sparrows helps to confirm the status signaling hypothesis
(C) indicate that in light of plumage variation patterns among Harris sparrows, the status signaling hypothesis should probably be modified
(D) demonstrate that Harris sparrows are the most appropriate subjects for the study of status signaling among birds
(E) suggest that the signaling of age-related differences in status is widespread among birds that form flocks



3. Which one of the following, if true, would most seriously undermine the validity of the results of the experiment discussed in the last paragraph?

(A) The live birds all came from different titmouse flocks.
(B) The physical characteristics of the stuffed dummies varied in ways other than just breast-stripe width.
(C) No live juvenile birds were included in the experiment.
(D) The food placed in the feeding tray was not the kind of food normally eaten by titmice in the wild.
(E) Even the live birds that acted aggressively did not actually physically attack the stuffed dummies.



4. Which one of the following best describes the organization of the passage?

(A) A hypothesis is introduced and studies relevant to the hypothesis are discussed and evaluated.
(B) A natural phenomenon is presented and several explanations for the phenomenon are examined in detail.
(C) Behavior is described, possible underlying causes for the behavior are reported and the likelihood of each cause is assessed.
(D) A scientific conundrum is explained and the history of the issue is recounted.
(E) A scientific theory is outlined and opinions for and against its validity as well as experiments supporting each side are compared.



5. According to the passage, which one of the following is true of Rohwer’s relationship to the status signaling hypothesis (SSH)?

(A) Although his research was designed to test the SSH, his data proved to be more relevant to other issues.
(B) He set out to confirm the SSH, but ended up revising it.
(C) He set out to disprove the SSH, but ended up accepting it.
(D) He altered the SSH by expanding it to encompass various types of signals.
(E) He advocated the SSH, but his research data failed to confirm it.



6. The passage suggests that among birds that form flocks, a bird of high status is most likely to have which one of the following?

(A) dark throat plumage
(B) greater-than-average body weight
(C) offspring of high status
(D) strong fighting ability
(E) frequent injuries



7. Which one of the following can be inferred about Harris sparrows from the passage?

(A) Among Harris sparrows, plumage differences signal individual status only within age groups.
(B) Among Harris sparrows, adults have priority of access to food over juveniles.
(C) Among Harris sparrows, juveniles with relatively dark plumage have status equal to that of adults with relatively light plumage.
(D) Juvenile Harris sparrows engage in aggressive interaction more frequently than do adult Harris sparrows.
(E) Harris sparrows engage in aggressive interaction less frequently than do greater titmice.



  • Source: LSAT Official PrepTest 20 (October 1996)
  • Difficulty Level: 650

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Many birds that form flocks compete through aggressive interaction for  [#permalink]

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New post 18 Oct 2019, 02:04
1
Hi everyone,
Took 15:45 minutes, including 5:15 minutes to read, write down paragraphs summaries and main point.

-----------------------------------------------------------------------------------------------


P1

Paragraph 1 starts off describing the behavior of birds in flocks. It appears that birds need to fight for shelter and resources and the higher the fighting ability, the higher the social status and hence the access to resources and shelters. HOWEVER the higher the battles the higher are the costs paid in terms of energy for example. So external features such as a plumage that indicates the fighting ability of a bird actually helps to keep access to resources and shelters without having to fight.

Brief summary: Social status and fighting ability affects access to resources and shelter and some external signals are a reflection of the two.

P2

Paragraph 2 talks about Rowher support to status signaling theory, citing Harris Sparrows. The conclusion is that birds with darker plumage most of the times win over birds with lighter plumage. Also among the same age this theory is validated. A natural question now arises: what about birds that are not in the same age group? What if a young bird with dark plumage fights against an old bird with dark plumage? Maybe the rest of the passage will answer such questions

Brief summary: The SST is introduced

P3

Paragraph 3 introduces 2 contrasts expressed by HOWEVER. The first one is that Rowher's claims are not supported by data. Through his experiments we can see that birds with darker plumage do not almost always win fights. The second contrast is that Harris' sparrows, if considered by age groups, do not have a special status based on the plumage color.

Brief summary: Data do not support R's claims and HS seem not useful as well

P4

Paragraph 4 advocates that the best evidence that we have is a feature of the titmouse. This feature correlates with status when other variables are held constant

Brief summary:beste evidence is associated with titmouse

P5

Paragraph 5 introduces an experiment that supports the theory for titmouse. A dummy is placed in front of food. Sometimes the dummy exhibit the feature signaling status and sometimes it does not. Then live birds' reactions are observed

Brief summary: An experiment supports the evidence related to the titmouse


Main point

The main point is to discuss the status signaling theory by considering different experiments and studies.




-----------------------------------------------------------------------------------------------

1. According to the passage, the status signaling hypothesis holds that the ability to display a recognizable external signal would have the effect on an individual bird of

Pre-thinking

Detail question

The status signaling theory is linked with the plumage element. At the end o paragraph one it is clearly stated that such plumage would allow birds to keep their social status without being too involved in fights


(A) enabling it to attract a mate of high status
Not in line with pre-thinking. incorrect

(B) allowing it to avoid costly aggressive interactions
In line with pre-thinking. correct

(C) decreasing its access to limited resources
Not in line with pre-thinking. incorrect

(D) making it less attractive to predatory species
Not in line with pre-thinking. incorrect

(E) increasing its fighting ability
Not in line with pre-thinking. incorrect


-----------------------------------------------------------------------------------------------

2. The author refers to the fact that adult Harris sparrows are usually dark throated (lines 31-32), in order to do which one of the following?

Pre-thinking

Purpose question

" However, the Harris sparrows’ age-related
plumage differences do not signal the status of
individual birds within an age class, and thus cannot
properly be included under the term “status signaling.”
"


(A) support the conclusion that plumage variation among Harris sparrows probably does not signal individual status
In line with pre-thinking. Hence correct

(B) argue that plumage variation among Harris sparrows helps to confirm the status signaling hypothesis
Not the purpose

(C) indicate that in light of plumage variation patterns among Harris sparrows, the status signaling hypothesis should probably be modified
Not in line with pre-thinking. incorrect

(D) demonstrate that Harris sparrows are the most appropriate subjects for the study of status signaling among birds(too extreme)
Not in line with pre-thinking. incorrect

(E)suggest that the signaling of age-related differences in status is widespread among birds that form flocks
Not in line with pre-thinking. incorrect


-----------------------------------------------------------------------------------------------

3. Which one of the following, if true, would most seriously undermine the validity of the results of the experiment discussed in the last paragraph?

Pre-thinking

Weaken question

The conclusion we want to weaken is the following: the wider the breast of the titmouse, the greater is success during aggressive interactions.
Now the experiment clearly states that when the live birds have a wider breast they act very aggressively but when their breast is narrower than the dummy they act submissively.

What if even though live birds with greater breast acted aggressively were not succesful in the end and escaped? Note that the experiment said that they were just aggressive but it does not tell use the result of that behavior


(A) The live birds all came from different titmouse flocks.
irrelevant

(B) The physical characteristics of the stuffed dummies varied in ways other than just breast-stripe width.
irrelevant

(C) No live juvenile birds were included in the experiment.
irrelevant

(D) The food placed in the feeding tray was not the kind of food normally eaten by titmice in the wild.
this is tempting but it has nothing to do with how titmouse interact with each others.

(E) Even the live birds that acted aggressively did not actually physically attack the stuffed dummies.
As we can see this option covers the gap that the experiments does not address. Titmouses acted aggressively but: were they successful or not? This option clearly undermines the conclusion that the breast width is a status signaling element

Can anyone explain B? Dear SajjadAhmad, may you share the official answer for this question?

-----------------------------------------------------------------------------------------------


4. Which one of the following best describes the organization of the passage?

Pre-thinking

Structure question

Birds behavior discussed--> SST introduced---> Rowher's studies undermined----> new best evidence introduced--->experiment supporting new best evidence described

(A) A hypothesis is introduced and studies relevant to the hypothesis are discussed and evaluated.
Seems quite in line with pre-thinking

(B) A natural phenomenon is presented and several explanations for the phenomenon are examined in detail.
Which natural phenomenon?

(C) Behavior is described, possible underlying causes for the behavior are reported and the likelihood of each cause is assessed.
Not mentioned

(D) A scientific conundrum is explained and the history of the issue is recounted.
No conundrum mentioned

(E) A scientific theory is outlined and opinions for and against its validity as well as experiments supporting each side are compared.
tempting but inconsistent. An hypothesis is presented. Not a theory.

-----------------------------------------------------------------------------------------------


5. According to the passage, which one of the following is true of Rohwer’s relationship to the status signaling hypothesis (SSH)?

Pre-thinking

Detail question

Let's refer to paragraph 2 and 3 to answer this question

(A) Although his research was designed to test the SSH, his data proved to be more relevant to other issues.
Not mentioned

(B) He set out to confirm the SSH, but ended up revising it.
Not mentioned

(C) He set out to disprove the SSH, but ended up accepting it.
Not mentioned

(D) He altered the SSH by expanding it to encompass various types of signals.
Not mentioned

(E) He advocated the SSH, but his research data failed to confirm it.
Mentioned

-----------------------------------------------------------------------------------------------


6. The passage suggests that among birds that form flocks, a bird of high status is most likely to have which one of the following?

Pre-thinking

Inference question

So we know that dark plumage is not a very solid evidence of higher status. So coming back to paragraph 1:

"The result of
repeated interactions between flock members is that
(5) each bird gains a particular [b]social status related to its
fighting ability
, with priority of access to resources
increasing with higher status."

We can infer from this that the higher the fighting ability the higher the social status since this implies more access to food and shelters
[/b]

(A) dark throat plumage
Tempting but the passage states that is not always true

(B) greater-than-average body weight
Body weight is mentioned as an element of analysis when the passage talks about titmouse. incorrect

(C) offspring of high status
Out of scope

(D) strong fighting ability
Correct

(E) frequent injuries
Cannot be inferred from the information given.


-----------------------------------------------------------------------------------------------

7. Which one of the following can be inferred about Harris sparrows from the passage?

Pre-thinking

Inference question

"adults,
usually dark throated, have higher status than juveniles,
who are usually light throated;"

This is a general consideration of sparrows: the young ones most of the times are light throated while the old ones are usually dark-throated. Hence since Harris sparrow's theory supports the paradigm: "dark wins over light" for the transitive property adults win over young sparrows


(A) Among Harris sparrows, plumage differences signal individual status only within age groups.
Not in line with pre-thinking

(B) Among Harris sparrows, adults have priority of access to food over juveniles.
Correct

(C) Among Harris sparrows, juveniles with relatively dark plumage have status equal to that of adults with relatively light plumage.
Not in line with pre-thinking

(D) Juvenile Harris sparrows engage in aggressive interaction more frequently than do adult Harris sparrows.
Not in line with pre-thinking

(E) Harris sparrows engage in aggressive interaction less frequently than do greater titmice.
Not in line with pre-thinking

-----------------------------------------------------------------------------------------------


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Re: Many birds that form flocks compete through aggressive interaction for  [#permalink]

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New post 19 Oct 2019, 08:23
1
auradediligodo Well i don't have OE of any of LSAT Official material, this explanation might help you.

Explanation


3. Which one of the following, if true, would most seriously undermine the validity of the results of the experiment discussed in the last paragraph?

Difficulty Level: 550

Explanation

The experiment in question was intended to test the effect of breast-stripe width on titmouse behavior. In order for this experiment’s results to be valid, all variables other than breast-stripe width must be held constant across all of the dummies. If the dummies varied, say, in size as well as in breast-stripe width, there’d have been no way to tell whether the titmice were responding to the dummies’ breast-stripe or their size.

(A) There’s nothing in the passage to suggest that titmice from different flocks would respond differently to the dummies.

(C) There’s also nothing in the passage to suggest that juveniles are inherently more aggressive or submissive than adult titmice.

(D) The issue isn’t whether the food in the tray was authentic, but how badly the titmice in the experiment wanted the food in the tray and what they were willing to do to get it.

(E) The issue isn’t physical violence per se, but aggressive vs. passive behavior in response to breast-stripe width.

Answer: B


Hope it helps
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Re: Many birds that form flocks compete through aggressive interaction for   [#permalink] 19 Oct 2019, 08:23
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