ants of most species leave a trail of chemicals

This topic has expert replies
User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members
On their way from their nest to a food source, ants of most species leave a trail of chemicals called pheromones. The ants use the scent of the pheromones to guide themselves between the food and their nest. All pheromones evaporate without a trace almost immediately when temperatures rise above 45 degrees Celsius (113 degree Fahrenheit), as is typical during afternoons in places such as the Sahara Desert.
The statements above, if true, most strongly support which one of the following?
(A) Most ants forage for food either only in the morning or only during the night.
(B) Most ants that do not use pheromones to mark the paths they take between their nest and food live in the Sahara Desert.
(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.
(D) If any ants do not use pheromones to navigate between food and their nest, those ants use a different substance that does not evaporate in temperatures above 45 degrees Celsius.
(E) If any Saharan ants forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working
Source: — Critical Reasoning |

Master | Next Rank: 500 Posts
Posts: 437
Joined: Sat Nov 22, 2008 5:06 am
Location: India
Thanked: 50 times
Followed by:1 members
GMAT Score:580

by beat_gmat_09 » Fri Apr 30, 2010 10:28 pm
thephoenix wrote:On their way from their nest to a food source, ants of most species leave a trail of chemicals called pheromones. The ants use the scent of the pheromones to guide themselves between the food and their nest. All pheromones evaporate without a trace almost immediately when temperatures rise above 45 degrees Celsius (113 degree Fahrenheit), as is typical during afternoons in places such as the Sahara Desert.
The statements above, if true, most strongly support which one of the following?
(A) Most ants forage for food either only in the morning or only during the night.
(B) Most ants that do not use pheromones to mark the paths they take between their nest and food live in the Sahara Desert.
(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.
(D) If any ants do not use pheromones to navigate between food and their nest, those ants use a different substance that does not evaporate in temperatures above 45 degrees Celsius.
(E) If any Saharan ants forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.
IMO B.

User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members

by thephoenix » Fri Apr 30, 2010 10:34 pm
beat_gmat_09 wrote:
thephoenix wrote:On their way from their nest to a food source, ants of most species leave a trail of chemicals called pheromones. The ants use the scent of the pheromones to guide themselves between the food and their nest. All pheromones evaporate without a trace almost immediately when temperatures rise above 45 degrees Celsius (113 degree Fahrenheit), as is typical during afternoons in places such as the Sahara Desert.
The statements above, if true, most strongly support which one of the following?
(A) Most ants forage for food either only in the morning or only during the night.
(B) Most ants that do not use pheromones to mark the paths they take between their nest and food live in the Sahara Desert.
(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.
(D) If any ants do not use pheromones to navigate between food and their nest, those ants use a different substance that does not evaporate in temperatures above 45 degrees Celsius.
(E) If any Saharan ants forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.
IMO B.
IMO
B is commenting about the group other than discussed in the stimulus , and therefore i eliminated it considering it Scope shift type of ans
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working

Master | Next Rank: 500 Posts
Posts: 379
Joined: Wed Apr 07, 2010 12:53 am
Location: Chennai,India
Thanked: 3 times

by paddle_sweep » Fri Apr 30, 2010 10:39 pm
IMO it's [spoiler]'E'[/spoiler].


Pls post OA.

Senior | Next Rank: 100 Posts
Posts: 34
Joined: Sat Apr 24, 2010 12:31 am

by kaushals » Sat May 01, 2010 2:45 pm
IMO [E][/spoiler]

Senior | Next Rank: 100 Posts
Posts: 34
Joined: Sat Apr 24, 2010 12:31 am

by kaushals » Sat May 01, 2010 2:46 pm
IMO E

Master | Next Rank: 500 Posts
Posts: 301
Joined: Sun Mar 21, 2010 3:18 pm
Thanked: 4 times

by ansumania » Sat May 01, 2010 7:54 pm
IMO C; Pl. post OA

Legendary Member
Posts: 576
Joined: Sat Mar 13, 2010 8:31 pm
Thanked: 97 times
Followed by:1 members

by liferocks » Sat May 01, 2010 9:23 pm
I will go with option C
was confused between C and E but the premise does not comment anything about the usage of pheromone and effectiveness of forage.
hence will go with C
"If you don't know where you are going, any road will get you there."
Lewis Carroll

GMAT Instructor
Posts: 1302
Joined: Mon Oct 19, 2009 2:13 pm
Location: Toronto
Thanked: 539 times
Followed by:164 members
GMAT Score:800

by Testluv » Sat May 01, 2010 9:36 pm
As liferocks points out, how efficiently they forage for food doesn't necessarily have anything to do with how well they go back and forth between the nest and food sources. Thus, choice E is outside the scope, and could easily be false.

Choice C must be true, and is correct. We know that ALL pheremones evaporate above a certain temperature, and that this threshold temperature is "typical" in afternoons in the Saharan desert. Thus, if there are some ants in the Sahara that forage for food only in the afernoon, they must be using something other than pheremones to guide themselves between food and nest.
_________

This:
IMO
B is commenting about the group other than discussed in the stimulus , and therefore i eliminated it considering it Scope shift type of ans
is great reasoning.
Kaplan Teacher in Toronto