It is currently 19 Oct 2017, 13:52

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

When there is less rainfall than normal, the water level of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

4 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 07 Sep 2010
Posts: 329

Kudos [?]: 1031 [4], given: 136

When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 02 Jul 2012, 08:14
4
This post received
KUDOS
13
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

71% (01:20) correct 29% (01:35) wrong based on 2371 sessions

HideShow timer Statistics

When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.

[Reveal] Spoiler:
Request you to please provide an explanation of A vs D.
Thanks
H
[Reveal] Spoiler: OA

_________________

+1 Kudos me, Help me unlocking GMAT Club Tests

Kudos [?]: 1031 [4], given: 136

Director
Director
User avatar
Status: Final Countdown
Joined: 17 Mar 2010
Posts: 536

Kudos [?]: 353 [0], given: 75

Location: India
GPA: 3.82
WE: Account Management (Retail Banking)
Re: When there is less rainfall than normal [#permalink]

Show Tags

New post 02 Jul 2012, 08:29
Less rainfall ---> slow movement of water ----> more algae
After the drought --->less water/flow----------->less algae

Answer must explain that even if the drought bring low water ,the growth of algae drops.

We need to prove that the growth of algae depends on other factors also OR the reason decremented algae is something else? OR there is no water at all for the growth of algae.

(D) says it clearly that "... rivers dry up completely for short intervals in periods of extreme drought.

Means-No water /or very less in a after-drought condition.
_________________

" Make more efforts "
Press Kudos if you liked my post

Kudos [?]: 353 [0], given: 75

2 KUDOS received
Manager
Manager
avatar
Joined: 19 Oct 2011
Posts: 129

Kudos [?]: 463 [2], given: 33

Location: India
Re: When there is less rainfall than normal [#permalink]

Show Tags

New post 02 Jul 2012, 09:09
2
This post received
KUDOS
(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
if the populations of species that feed on algae tend to fall ---> less feeding on algae --> algae population will increase.

We want to resolve the paradox ( :idea: we want to find a reason why algae population goes down during extreme drought).
D is a clear winner in this case. :!:
_________________

Encourage me by pressing the KUDOS if you find my post to be helpful.



Help me win "The One Thing You Wish You Knew - GMAT Club Contest"
http://gmatclub.com/forum/the-one-thing-you-wish-you-knew-gmat-club-contest-140358.html#p1130989

Kudos [?]: 463 [2], given: 33

Expert Post
4 KUDOS received
Veritas Prep GMAT Instructor
User avatar
G
Joined: 16 Oct 2010
Posts: 7674

Kudos [?]: 17361 [4], given: 232

Location: Pune, India
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 03 Jul 2012, 21:06
4
This post received
KUDOS
Expert's post
imhimanshu wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers fl ow more slowly.
Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of
water generally increases when there has been little rain. By contrast, however, following a period of extreme
drought, algae levels are low even in very slow-moving river water.
Which of the following, if true, does most to explain the contrast described above?
(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of
the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the fl ow has
been controlled by damming than in rivers that fl ow freely.

Request you to please provide an explanation of A vs D.
Thanks
H


Responding to a pm:

This is an explain the paradox question. What is the paradox? When there is less rainfall, rivers move slowly and hence algae levels are high. When there is extremely less rainfall, algae levels are low even in very slow moving rivers.

You would expect algae levels to be very high in case of very slow moving rivers but it is not so. You need to explain why the algae levels are low in very slow moving rivers in case of drought.

Option (A) is incorrect. It says that during drought, some species that feed on algae fall. This means algae's predators are few and hence, algae should thrive and their levels should be high. This certainly doesn't explain why their levels fall in case of drought.

Option (D) explains the paradox. In case of drought, rivers actually dry up completely for short intervals. Hence, all algae in the river would die out if it dries up. Therefore, the algae population would be low.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Kudos [?]: 17361 [4], given: 232

Senior Manager
Senior Manager
avatar
Joined: 16 Dec 2011
Posts: 423

Kudos [?]: 232 [0], given: 70

Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 19 Apr 2013, 06:31
1
This post was
BOOKMARKED
imhimanshu wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.

Premises:
(1) Habitat of algae is river water.
(2) Algae grow best in slow-moving water, when there is less rainfall than normal.
(3) After extreme drought, even in very slow-moving river water, algae levels are low.

Question is to resolve the apparent paradox on low level of algae in slow-moving water when it is after extreme drought.

A) If number of algae-eaters become less, algae level is supposed to be higher. Does not give any information on why algae level becomes lower following drought.
B) This says how algae level can be higher. There is no information on why algae level becomes lower following drought.
C) There is no given on how living condition of other species can affect algae level.
D) The statement implies that dry riverbed, which does not provide normal living condition for algae, triggers death of algae to some extent. Immediately after death of some algae, even though there is very slow-moving river water following recovery from drought, it is natural that algae level would be low. The given information here resolves the paradox.
E) There is no information on the factors affecting given situation, i.e., algae level, following a period of extreme drought, in slow-moving river water.

Correct answer is D.

Kudos [?]: 232 [0], given: 70

Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Joined: 16 Jun 2012
Posts: 1127

Kudos [?]: 3478 [0], given: 123

Location: United States
Premium Member
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 19 Apr 2013, 16:55
imhimanshu wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.

[Reveal] Spoiler:
Request you to please provide an explanation of A vs D.
Thanks
H


A cannot be the answer. if populations of some of the species that feed on algae tend to fall, algae levels must increase. A is the opposite answer.
KEY here is algae grow best in slow-moving water, if there's no water, algae cannot grow. Hence, D is correct.

Hope it helps.
_________________

Please +1 KUDO if my post helps. Thank you.

"Designing cars consumes you; it has a hold on your spirit which is incredibly powerful. It's not something you can do part time, you have do it with all your heart and soul or you're going to get it wrong."

Chris Bangle - Former BMW Chief of Design.

Kudos [?]: 3478 [0], given: 123

Senior Manager
Senior Manager
avatar
Joined: 06 Aug 2011
Posts: 390

Kudos [?]: 234 [0], given: 82

Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 15 Feb 2014, 01:52
its D.. bridges the gap b/w two given situations..

algae population increases in drough condition


Australian rivers dry up completely for short intervals in periods of extreme drought.


algae population didnt increase in extreme drought condition



what do happen in extreme drought condition for that algae population didnt increase..highlighted words fill the gap and resolve it !
_________________

Bole So Nehal.. Sat Siri Akal.. Waheguru ji help me to get 700+ score !

Kudos [?]: 234 [0], given: 82

Math Forum Moderator
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3003

Kudos [?]: 1087 [0], given: 325

Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 15 Feb 2014, 10:55
imhimanshu wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.


Less Rainfall ---- > Water Level of Australia falls -------> Rivers flow slowly -------- > Increase in amount of algae per unit area.

Extreme drought ------- > Level of algae low even in slow moving water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.

Irrelevant.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.

Irrelevant.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.

Irrelevant.

(D) Australian rivers dry up completely for short intervals in periods of extreme drought.

If rivers dry up completely for short periods , then there must be increased algae population during that period.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.

Out of scope and irrelevant.
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Kudos [?]: 1087 [0], given: 325

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 01 Oct 2013
Posts: 10119

Kudos [?]: 261 [0], given: 0

Premium Member
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 21 Jan 2016, 14:42
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.

Kudos [?]: 261 [0], given: 0

Math Forum Moderator
User avatar
P
Joined: 13 Apr 2015
Posts: 1503

Kudos [?]: 1107 [0], given: 884

Location: India
Concentration: Strategy, General Management
WE: Information Technology (Consulting)
GMAT ToolKit User Premium Member CAT Tests
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 11 May 2016, 05:37
Less rainfall --> Water level drops + rivers slow more slowly --> Algae population increases
Amount of algae per unit of water increases when there is little rain

Conclusion: After a period of extreme drought, algae levels are low even in slow moving water.

Possible explanation: Algae require atleast some quantity of water to thrive.

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall. - Incorrect - Opposite. Does not help resolve the paradox.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae. - Incorrect - States one more fact but does not answer the conclusion.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there. - Incorrect - Does not help resolve the paradox.

(D) Australian rivers dry up completely for short intervals in periods of extreme drought. - Correct - Since the rivers completely dry out algae cannot thrive in such conditions.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely. - Incorrect - Out of context.

Answer: D

Kudos [?]: 1107 [0], given: 884

Senior Manager
Senior Manager
User avatar
B
Joined: 27 Mar 2016
Posts: 338

Kudos [?]: 111 [0], given: 26

Location: United States (CO)
GMAT 1: 770 Q51 V44
GPA: 3.69
WE: Analyst (Consulting)
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 19 Jun 2016, 01:56
I totally thought the drought killed algae because the rivers would dry up, not realizing that that the rivers would dry up is an assumption. I expected the correct answer choice to say that droughts kill algae. Close enough! :-D

Kudos [?]: 111 [0], given: 26

Intern
Intern
avatar
Joined: 05 Nov 2014
Posts: 15

Kudos [?]: [0], given: 39

Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 24 Jun 2016, 05:20
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
-- This is strengthening the situation for more algae to be there in drought period

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
-- This is again saying algae level to be higher against the situation
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
-- Out of Scope
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
-- Best possible reason
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
-- Out of scope

Kudos [?]: [0], given: 39

Intern
Intern
User avatar
B
Joined: 20 Apr 2015
Posts: 30

Kudos [?]: [0], given: 111

Concentration: Technology, Leadership
GPA: 3.9
GMAT ToolKit User
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 09 Mar 2017, 02:33
Question stem says : Algae grow more in slow moving water. In contrast, but after a drought the algae levels are low even in very slow-moving river water.

This brings us to an assumption that something is wrong with the slow moving water and hence algae level is low.
Which option will be apt? Only D makes sense. Rivers dry up and there is no slow moving water for algae to grow.

Kudos [?]: [0], given: 111

Senior Manager
Senior Manager
User avatar
G
Joined: 04 Sep 2015
Posts: 479

Kudos [?]: 77 [0], given: 18

Location: India
WE: Information Technology (Computer Software)
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 09 Mar 2017, 12:19
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely

A:other species is out of scope.
B:this does not resolve the paradox.
C:other secies is out of scope.
D:Correct answer,when the river dries up completely the algae also dies,and starts to grow from start once the water startes flowing.
E:out of scope. Also,Damming is limited

=======================
PreThinking:Resolve paradox question require one to find the connection between two opposite premises.
=======================

Kudos [?]: 77 [0], given: 18

Intern
Intern
avatar
Joined: 26 May 2017
Posts: 2

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

Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 26 May 2017, 14:43
While D is clearly the best answer of the available choices, this answer doesn't logically explain the paradox.

Sure, if a drought is so bad that there is no water at all, there won't be any algae.

However, the question asks us to explain the contrast between higher levels of algae in slow-moving rivers and lower levels in very slow-moving rivers. Here, we are (or should be) looking for a reason to explain why algae levels might not be inversely correlated with river speeds in all cases, as one would expect. The fact that rivers sometimes dry up completely doesn't address this contrast since in that case, the rivers aren't moving at all. We're told the algae's habitat is river water, so why do we care about when there isn't any river water at all? It's not relevant.
:roll:

This seems like a prime example of having to select the best answer, not the ideal answer. I'm absolutely overthinking this one. Sorry, all!

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

Expert Post
Veritas Prep GMAT Instructor
User avatar
G
Joined: 16 Oct 2010
Posts: 7674

Kudos [?]: 17361 [0], given: 232

Location: Pune, India
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 27 May 2017, 22:05
30moreptsplease wrote:
While D is clearly the best answer of the available choices, this answer doesn't logically explain the paradox.

Sure, if a drought is so bad that there is no water at all, there won't be any algae.

However, the question asks us to explain the contrast between higher levels of algae in slow-moving rivers and lower levels in very slow-moving rivers. Here, we are (or should be) looking for a reason to explain why algae levels might not be inversely correlated with river speeds in all cases, as one would expect. The fact that rivers sometimes dry up completely doesn't address this contrast since in that case, the rivers aren't moving at all. We're told the algae's habitat is river water, so why do we care about when there isn't any river water at all? It's not relevant.
:roll:

This seems like a prime example of having to select the best answer, not the ideal answer. I'm absolutely overthinking this one. Sorry, all!


Not really. The correct option makes complete sense. You missed out one word in the argument - "following" :
By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

So if there has been a period of extreme draught in the recent past (but is now over), algae levels are low even in very slow moving river water because the river had dried up completely during the draught. Obviously, that would have killed algae too since its habitat would have gone. So now, even though the water is back and is very slow moving, the algae population is low.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Kudos [?]: 17361 [0], given: 232

Intern
Intern
avatar
Joined: 26 May 2017
Posts: 2

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

Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 28 May 2017, 08:26
VeritasPrepKarishma wrote:
30moreptsplease wrote:
While D is clearly the best answer of the available choices, this answer doesn't logically explain the paradox.

Sure, if a drought is so bad that there is no water at all, there won't be any algae.

However, the question asks us to explain the contrast between higher levels of algae in slow-moving rivers and lower levels in very slow-moving rivers. Here, we are (or should be) looking for a reason to explain why algae levels might not be inversely correlated with river speeds in all cases, as one would expect. The fact that rivers sometimes dry up completely doesn't address this contrast since in that case, the rivers aren't moving at all. We're told the algae's habitat is river water, so why do we care about when there isn't any river water at all? It's not relevant.
:roll:

This seems like a prime example of having to select the best answer, not the ideal answer. I'm absolutely overthinking this one. Sorry, all!


Not really. The correct option makes complete sense. You missed out one word in the argument - "following" :
By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

So if there has been a period of extreme draught in the recent past (but is now over), algae levels are low even in very slow moving river water because the river had dried up completely during the draught. Obviously, that would have killed algae too since its habitat would have gone. So now, even though the water is back and is very slow moving, the algae population is low.

Whelp, so much for my reading comprehension! Thanks for clarifying that and putting my mind at ease.

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

2 KUDOS received
Senior Manager
Senior Manager
User avatar
S
Joined: 04 Oct 2015
Posts: 394

Kudos [?]: 24 [2], given: 232

Location: Viet Nam
Concentration: Finance, Economics
GPA: 3.56
Premium Member Reviews Badge CAT Tests
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 08 Jun 2017, 06:55
2
This post received
KUDOS
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
--> This option seems to exacerbate the contrast.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
--> This option seems to exacerbate the contrast.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
--> This option does nothing to explain the contrast.

(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
--> correct.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
--> irrelevant information.
_________________

Do not pray for an easy life, pray for the strength to endure a difficult one - Bruce Lee

Kudos [?]: 24 [2], given: 232

1 KUDOS received
Intern
Intern
User avatar
B
Joined: 11 Jan 2017
Posts: 3

Kudos [?]: 1 [1], given: 1

Location: India
Concentration: Marketing, Technology
GPA: 2.51
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 20 Jun 2017, 10:02
1
This post received
KUDOS
leanhdung wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
--> This option seems to exacerbate the contrast.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
--> This option seems to exacerbate the contrast.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
--> This option does nothing to explain the contrast.

(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
--> correct.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
--> irrelevant information.



Thanks for the detailed explanation! What level might this question be of? 600?

Kudos [?]: 1 [1], given: 1

1 KUDOS received
Senior Manager
Senior Manager
User avatar
S
Joined: 04 Oct 2015
Posts: 394

Kudos [?]: 24 [1], given: 232

Location: Viet Nam
Concentration: Finance, Economics
GPA: 3.56
Premium Member Reviews Badge CAT Tests
Re: When there is less rainfall than normal, the water level of [#permalink]

Show Tags

New post 20 Jun 2017, 10:24
1
This post received
KUDOS
sarthakkhanna wrote:
leanhdung wrote:
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
--> This option seems to exacerbate the contrast.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
--> This option seems to exacerbate the contrast.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
--> This option does nothing to explain the contrast.

(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
--> correct.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
--> irrelevant information.



Thanks for the detailed explanation! What level might this question be of? 600?


This question is tagged at level 700+ :P
_________________

Do not pray for an easy life, pray for the strength to endure a difficult one - Bruce Lee

Kudos [?]: 24 [1], given: 232

Re: When there is less rainfall than normal, the water level of   [#permalink] 20 Jun 2017, 10:24

Go to page    1   2    Next  [ 21 posts ] 

Display posts from previous: Sort by

When there is less rainfall than normal, the water level of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.