Loggerhead turtles

This topic has expert replies
Legendary Member
Posts: 549
Joined: Wed Jan 06, 2010 7:00 am
Thanked: 16 times
Followed by:3 members

Loggerhead turtles

by ssgmatter » Thu Jul 08, 2010 7:30 am
Loggerhead turtles live and breed in distinct groups, of which some are in the Pacific Ocean and some are in the Atlantic. New evidence suggests that juvenile pacific loggerheads that feed near the Baja peninsula hatch in Japanese waters 10,000 kilometers away. Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites.
Which one of the following, if true, most seriously weakens the reasoning above?
(A) Nesting sites of loggerhead turtles have been found off the Pacific coast of North America several thousand kilometers north of the Baja peninsula.
(B) The distance between nesting sites and feeding sites of Atlantic loggerhead turtles is less than 5,000 kilometers.
(C) Loggerhead hatchlings in Japanese waters have been declining in number for the last decade while the number of nesting sites near the Baja peninsula had remained constant.
(D) Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from Atlantic loggerhead turtles.
(E) Commercial aquariums have been successfully breeding Atlantic loggerheads with Pacific loggerheads fro the last five years.
Best-
Amit
Source: — Critical Reasoning |

User avatar
Master | Next Rank: 500 Posts
Posts: 392
Joined: Sun May 16, 2010 2:42 am
Location: Bangalore, India
Thanked: 116 times
Followed by:10 members
GMAT Score:770

by albatross86 » Thu Jul 08, 2010 7:43 am
Fact 1: Atlantic and Pacific loggerheads are two DISTINCT groups.
Fact 2: 95% of DNA samples from Baja & Japanese match

Conclusion: Fact 2 suggests that these turtles that feed in Baja actually hatched in Japanese waters.

WEAKENER

A. There are nesting sites north of Baja - this is irrelevant as it does not dispute the DNA evidence.

B. This talks about something completely different- Atlantic turtle nesting and feeding sites. Irrelevant.

C. An irrelevant statistic.

D. Booyah! 95% of the DNA samples also match the Atlantic turtles. Now we could then infer, by the same reasoning, that these turtles hatched in Atlantic waters, which contradicts both Fact 1 (which claims that the two are distinct) and the conclusion!

E. Aquariums have been breeding them - so what? We are talking of the wild ones and comparing the Bajan ones with those at the Jap nesting sites.

Pick D.
~Abhay

Believe those who are seeking the truth. Doubt those who find it. -- Andre Gide

Legendary Member
Posts: 549
Joined: Wed Jan 06, 2010 7:00 am
Thanked: 16 times
Followed by:3 members

by ssgmatter » Thu Jul 08, 2010 7:48 am
albatross86 wrote:Fact 1: Atlantic and Pacific loggerheads are two DISTINCT groups.
Fact 2: 95% of DNA samples from Baja & Japanese match

Conclusion: Fact 2 suggests that these turtles that feed in Baja actually hatched in Japanese waters.

WEAKENER

A. There are nesting sites north of Baja - this is irrelevant as it does not dispute the DNA evidence.

B. This talks about something completely different- Atlantic turtle nesting and feeding sites. Irrelevant.

C. An irrelevant statistic.

D. Booyah! 95% of the DNA samples also match the Atlantic turtles. Now we could then infer, by the same reasoning, that these turtles hatched in Atlantic waters, which contradicts both Fact 1 (which claims that the two are distinct) and the conclusion!

E. Aquariums have been breeding them - so what? We are talking of the wild ones and comparing the Bajan ones with those at the Jap nesting sites.

Pick D.
Thankyou dude!

Can you please explain the reason for why C is incorrect in more details.

Cheers!
Best-
Amit

User avatar
Master | Next Rank: 500 Posts
Posts: 392
Joined: Sun May 16, 2010 2:42 am
Location: Bangalore, India
Thanked: 116 times
Followed by:10 members
GMAT Score:770

by albatross86 » Thu Jul 08, 2010 7:54 am
C. Loggerhead hatchlings in Japanese waters have been declining in number for the last decade while the number of nesting sites near the Baja peninsula had remained constant.
So we have two distinct facts here:
1. The number of turtles that have hatched in Japanese waters has been decreasing over the past 10 years
2. Number of nesting sites in Baja has been constant.

This does not mean that the Bajan turtles could not have hatched in Japanese waters. Perhaps the number of turtles that nest in this peninsula has also decreased proportionally.

You could imagine that the two are somehow related in order to argue that perhaps this disproves the conclusion. But this would require you to bridge these two facts and accept them as related/connected and also to make several assumptions. Remember we are not looking for a counter-argument, but something which if true directly attacks the stated argument.

As a true statement, these statistics do not serve to weaken the argument that the turtles that nest in Baja, hatched in Japanese waters.
~Abhay

Believe those who are seeking the truth. Doubt those who find it. -- Andre Gide