Neotropical coastal mangrove forests are usually “zonal,” wi : GMAT Reading Comprehension (RC)
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# Neotropical coastal mangrove forests are usually “zonal,” wi

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Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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30 Sep 2013, 10:41
4
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Expert's post
Question 1
00:00

Question Stats:

76% (03:09) correct 24% (05:30) wrong based on 25

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Question 2
00:00

Question Stats:

70% (01:33) correct 30% (01:00) wrong based on 23

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Question 3
00:00

Question Stats:

74% (02:45) correct 26% (01:24) wrong based on 23

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Practice Passage
Passage No.: 12
Questions: 61 to 63
Page: 44, 45
Difficulty:

Neotropical coastal mangrove forests are usually “zonal,” with certain mangrove species found predominantly in the seaward portion of the habitat
and other mangrove species on the more landward portions of the coast. The earliest research on mangrove forests produced descriptions of species distribution from shore to land, without exploring the causes of the distributions.

The idea that zonation is caused by plant succession was first expressed by J. H. Davis in a study of Florida mangrove forests. According to Davis’ scheme, the shoreline is being extended in a seaward direction because of the “land-building” role of mangroves, which, by trapping sediments over time, extend the shore. As a habitat gradually becomes more inland as the shore extends, the “land-building” species are replaced. This continuous process of accretion and succession would be interrupted only by hurricanes or storm flushings.

Recently the universal application of Davis’ succession paradigm has been challenged. It appears that in areas where weak currents and weak tidal energies allow the accumulation of sediments, mangroves will follow land formation and accelerate the rate of soil accretion; succession will proceed according to Davis’ scheme. But on stable coastlines, the distribution of mangrove species results in other patterns of zonation; “land building” does not occur.

To find a principle that explains the various distribution patterns, several researchers have looked to salinity and its effects on mangroves. While mangroves can develop in fresh water, they can also thrive in salinities as high as 2.5 times that of seawater. However, those mangrove species found in freshwater habitats do well only in the absence of competition, thus suggesting that salinity tolerance is a critical factor in competitive success among mangrove species. Research suggests that mangroves will normally dominate highly saline regions, although not because they require salt. Rather, they are metabolically efficient (and hence grow well) in portions of an environment whose high salinity excludes plants adapted to lower salinities. Tides create different degrees of salinity along a coastline. The characteristic mangrove species of each zone should exhibit a higher metabolic efficiency at that salinity than will any potential invader, including other species of mangrove.

Q1 :- The primary purpose of the passage is to

(A) refute the idea that the zonation exhibited in mangrove forests is caused by adaptation to salinity
(B) describe the pattern of zonation typically found in Florida mangrove forests
(C) argue that Davis’ succession paradigm cannot be successfully applied to Florida mangrove forests
(D) discuss hypotheses that attempt to explain the zonation of coastal mangrove forests
(E) establish that plants that do well in saline forest environments require salt to achieve maximum metabolic efficiency

[Reveal] Spoiler:
D

Q2 :- According to the passage, the earliest research on mangrove forests produced which of the following?

(A) Data that implied random patterns of mangrove species distribution
(B) Descriptions of species distributions suggesting zonation
(C) Descriptions of the development of mangrove forests over time
(D) Reclassification of species formerly thought to be identical
(E) Data that confirmed the “land-building” role of mangroves

[Reveal] Spoiler:
B

Q3 :- It can be inferred from the passage that Davis’ paradigm does NOT apply to which of the following?

(A) The shoreline of Florida mangrove forests first studied by Davis
(B) A shoreline in an area with weak currents
(C) A shoreline in an area with weak tidal energy
(D) A shoreline extended by “land-building” species of mangroves
(E) A shoreline in which few sediments can accumulate

[Reveal] Spoiler:
E

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

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MBA Section Director
Status: On vacation...
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Kudos [?]: 2889 [0], given: 2164

Re: Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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02 Oct 2013, 08:52
## Reserved for Official Explanation ##
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Re: Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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01 Mar 2014, 01:05
I chose DBD.. tuk 8 mints

can anyone send official explanation..?? plz
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Kudos [?]: 6 [1] , given: 18

Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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22 Apr 2015, 06:44
1
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Here is my attempt at an explanation of my choices (these are not official nor have I seen OE):
Answers: 1) D 2) B 3) E
Q1 :- The primary purpose of the passage is to

(A) refute the idea that the zonation exhibited in mangrove forests is caused by adaptation to salinity -- Salinity principle is discussed in Para-4 and the author does not refute this principle
(B) describe the pattern of zonation typically found in Florida mangrove forests -- Florida is merely the location where J.H. Davis conducted his research
(C) argue that Davis’ succession paradigm cannot be successfully applied to Florida mangrove forests -- Author does not argue Davis' paradigm can't work in Florida. The author brings up other researchers challenging the paradigm in non-weak current/tidal energy locations
(D) discuss hypotheses that attempt to explain the zonation of coastal mangrove forests -- General statement encompassing the entire passage and the discussion that takes place
(E) establish that plants that do well in saline forest environments require salt to achieve maximum metabolic efficiency -- Only partial scope as this is mention in the fourth paragraph only

Q2 :- According to the passage, the earliest research on mangrove forests produced which of the following?

(A) Data that implied random patterns of mangrove species distribution -- No random pattern mentioned
(B) Descriptions of species distributions suggesting zonation -- "The earliest research on mangrove forests produced descriptions of species distribution from shore to land, without exploring the causes of the distributions"
(C) Descriptions of the development of mangrove forests over time -- Described distribution, not development
(D) Reclassification of species formerly thought to be identical -- Out of Scope
(E) Data that confirmed the “land-building” role of mangroves -- No data given

Q3 :- It can be inferred from the passage that Davis’ paradigm does NOT apply to which of the following?

(A) The shoreline of Florida mangrove forests first studied by Davis -- Davis' paradigm does apply to the shoreline of Florida
(B) A shoreline in an area with weak currents -- Davis' paradigm does apply to areas with weak currents
(C) A shoreline in an area with weak tidal energy -- Davis' paradigm does apply to areas with weak tidal energy
(D) A shoreline extended by “land-building” species of mangroves -- if the paradigm occurs then "land-building" takes place
(E) A shoreline in which few sediments can accumulate -- Combining "But on stable coastlines, the distribution of mangrove species results in other patterns of zonation; “land building” does not occur." and "“land-building” role of mangroves, which, by trapping sediments over time, extend the shore" we can infer that with few accumulated sediments, the paradigm will not work (this is precisely why the paradigm was challenged by other researchers)
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Re: Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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03 Jul 2016, 06:04
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Top Contributor
All correct. 8 mins.
~4 mins for Para.Poor timing on Para reading.
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Re: Neotropical coastal mangrove forests are usually “zonal,” wi [#permalink]

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25 Jul 2016, 00:42
all correct in 8min. Passage gets much time for details
Re: Neotropical coastal mangrove forests are usually “zonal,” wi   [#permalink] 25 Jul 2016, 00:42
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