While the most abundant and dominant species within a : GMAT Reading Comprehension (RC)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 17 Jan 2017, 05:18

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# While the most abundant and dominant species within a

Author Message
TAGS:

### Hide Tags

Intern
Joined: 03 Aug 2011
Posts: 46
Followers: 1

Kudos [?]: 17 [2] , given: 17

While the most abundant and dominant species within a [#permalink]

### Show Tags

29 May 2012, 10:14
2
KUDOS
2
This post was
BOOKMARKED
Question 1
00:00

Question Stats:

68% (03:44) correct 32% (02:00) wrong based on 44

### HideShow timer Statistics

Question 2
00:00

Question Stats:

90% (01:57) correct 10% (01:10) wrong based on 39

### HideShow timer Statistics

Question 3
00:00

Question Stats:

71% (01:00) correct 29% (01:07) wrong based on 41

### HideShow timer Statistics

Question 4
00:00

Question Stats:

73% (02:44) correct 28% (01:29) wrong based on 40

### HideShow timer Statistics

While the most abundant and dominant species within a particular ecosystem is often crucial in perpetuating the ecosystem, a “keystone” species, here defined as one whose effects are much larger than would be predicted from its abundance, can also play a vital role. But because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic. It might seem that certain traits would clearly define a species as a keystone species; for example, Pisaster ochraceus is often a keystone predator because it consumes and suppresses mussel populations, which in the absence of this starfish can be a dominant species. But such predation on a dominant or potentially dominant species occurs in systems that do as well as in systems that do not have species that play keystone roles. Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels. Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species in particular may dramatically affect ecosystems).
1. The passage mentions which of the following as a factor that affects the role of P. ochraceus as a keystone species within different habitats?
A. The degree to which the habitat is sheltered from waves
B. The degree to which other animals within a habitat prey on mussels
C. The fact that mussel populations are often not dominant within some habitats occupied by P. ochraceus
D. The size of the P. ochraceus population within the habitat
E. The fact that there is great species diversity within some habitats occupied by P. ochraceus
[Reveal] Spoiler:
A

2. Which of the following hypothetical experiments most clearly exemplifies the method of identifying species, roles that the author considers problematic?
A. A population of seals in an Arctic habitat is counted in order to determine whether it is the dominant species in that ecosystem,
B. A species of fish that is a keystone species in one marine ecosystem is introduced into another marine ecosystem to see whether the species will come to occupy a keystone role.
C. In order to determine whether a species of monkey is a keystone species within a particular ecosystem, the monkeys are removed from that ecosystem and the ecosystem is then studied.
D. Different mountain ecosystems are compared to determine how geography affects a particular species, ability to dominate its ecosystem.
E. In a grassland experiencing a changing climate, patterns of species extinction are traced in order to evaluate the effect of climate changes on keystone species in that grassland.
[Reveal] Spoiler:
C

3. Which of the following, if true, would most clearly support the argument about keystone status advanced in the last sentence of the passage?
A. A species of bat is primarily responsible for keeping insect populations within an ecosystem low, and the size of the insect population in turn affects bird species within that ecosystem.
B. A species of iguana occupies a keystone role on certain tropical islands, but does not play that role on adjacent tropical islands that are inhabited by a greater number of animal species.
C. Close observation of a savannah ecosystem reveals that more species occupy keystone roles within that ecosystem than biologists had previously believed.
D. As a keystone species of bee becomes more abundant it has a larger effect on the ecosystem it inhabits.
E. A species of moth that occupies a keystone role in a prairie habitat develops coloration patterns that camouflage it from potential predators.
[Reveal] Spoiler:
B

4. The passage suggests which of the following about the identification of a species as a keystone species?
A. Such an identification depends primarily on the species’ relationship to the dominant species.
B. Such an identification can best be made by removing the species from a particular ecosystem and observing changes that occur in the ecosystem.
C. Such an identification is likely to be less reliable as an ecosystem becomes less diverse.
D. Such an identification seems to depend on various factors within the ecosystem.
E. Such an identification can best be made by observing predation behavior.
[Reveal] Spoiler:
D

[Reveal] Spoiler: Question #1 OA
[Reveal] Spoiler: Question #2 OA
[Reveal] Spoiler: Question #3 OA
[Reveal] Spoiler: Question #4 OA

_________________

Keep your eyes on the prize: 750

If you have any questions
New!
Intern
Joined: 03 Aug 2011
Posts: 46
Followers: 1

Kudos [?]: 17 [0], given: 17

Re: OG 13 - RC [#permalink]

### Show Tags

29 May 2012, 10:22
_________________

Keep your eyes on the prize: 750

Intern
Joined: 03 Aug 2011
Posts: 46
Followers: 1

Kudos [?]: 17 [0], given: 17

Re: OG 13 - RC [#permalink]

### Show Tags

29 May 2012, 10:26
plz prepare more explanations
_________________

Keep your eyes on the prize: 750

Intern
Joined: 02 Aug 2013
Posts: 4
Concentration: Accounting
GMAT 1: 650 Q49 V30
GPA: 3.5
Followers: 0

Kudos [?]: 3 [0], given: 32

Re: While the most abundant and dominant species within a [#permalink]

### Show Tags

10 Aug 2013, 01:39
1
This post was
BOOKMARKED
1. The passage mentions which of the following as a factor that affects the role of P. ochraceus as a keystone species within different habitats?
A. The degree to which the habitat is sheltered from waves Correct. In more wave-sheltered habitats the impact of P. ochraceus is weak or nonexistent.
B. The degree to which other animals within a habitat prey on mussels
C. The fact that mussel populations are often not dominant within some habitats occupied by P. ochraceus
D. The size of the P. ochraceus population within the habitat
E. The fact that there is great species diversity within some habitats occupied by P. ochraceus

2. Which of the following hypothetical experiments most clearly exemplifies the method of identifying species, roles that the author considers problematic?
A. A population of seals in an Arctic habitat is counted in order to determine whether it is the dominant species in that ecosystem,
B. A species of fish that is a keystone species in one marine ecosystem is introduced into another marine ecosystem to see whether the species will come to occupy a keystone role.
C. In order to determine whether a species of monkey is a keystone species within a particular ecosystem, the monkeys are removed from that ecosystem and the ecosystem is then studied. Correct. A problematic way to identify a keystone is to move the species and oberve changes in the ecosystem.
D. Different mountain ecosystems are compared to determine how geography affects a particular species, ability to dominate its ecosystem.
E. In a grassland experiencing a changing climate, patterns of species extinction are traced in order to evaluate the effect of climate changes on keystone species in that grassland.

3. Which of the following, if true, would most clearly support the argument about keystone status advanced in the last sentence of the passage?
A. A species of bat is primarily responsible for keeping insect populations within an ecosystem low, and the size of the insect population in turn affects bird species within that ecosystem.No reflection of a particular geography, community diversity or length of species interaction.
B. A species of iguana occupies a keystone role on certain tropical islands, but does not play that role on adjacent tropical islands that are inhabited by a greater number of animal species. Correct. It refers to the community diversity.
C. Close observation of a savannah ecosystem reveals that more species occupy keystone roles within that ecosystem than biologists had previously believed.
D. As a keystone species of bee becomes more abundant it has a larger effect on the ecosystem it inhabits.Not related
E. A species of moth that occupies a keystone role in a prairie habitat develops coloration patterns that camouflage it from potential predators.Not related

4. The passage suggests which of the following about the identification of a species as a keystone species?
A. Such an identification depends primarily on the species’ relationship to the dominant species.
B. Such an identification can best be made by removing the species from a particular ecosystem and observing changes that occur in the ecosystem. Author mentioned this method is problematic.
C. Such an identification is likely to be less reliable as an ecosystem becomes less diverse.
D. Such an identification seems to depend on various factors within the ecosystem.Correct. Keystone status appears to depend on context.
E. Such an identification can best be made by observing predation behavior. Predation behavior also occurs in systems that do not have keystones.
GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10528
Followers: 917

Kudos [?]: 203 [0], given: 0

Re: While the most abundant and dominant species within a [#permalink]

### Show Tags

20 May 2016, 23:21
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Re: While the most abundant and dominant species within a   [#permalink] 20 May 2016, 23:21
Similar topics Replies Last post
Similar
Topics:
6 Two divergent definitions have dominated sociologists' 15 14 Jul 2013, 04:15
9 While the most abundant and dominant species within a 14 21 Nov 2012, 09:34
1 Two divergent definitions have dominated sociologists 6 29 Jul 2012, 12:50
Two divergent definitions have dominated sociologistsï¿½ 3 09 Jul 2009, 01:54
33 Historians have identified two dominant currents in 24 04 May 2008, 19:58
Display posts from previous: Sort by