LSAT 141 – Section 2 – Question 22

LSAT 141 - Section 2 - Question 22

September 2014

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT141 S2 Q22
+LR
Strengthen +Streng
Causal Reasoning +CausR
A
54%
165
B
28%
161
C
7%
160
D
10%
158
E
1%
155
147
161
175
 +Hardest 146.882 +SubsectionMedium

Because the native salmon in Lake Clearwater had nearly disappeared, sockeye salmon were introduced in 1940. After being introduced, this genetically uniform group of sockeyes split into two distinct populations that do not interbreed, one inhabiting deep areas of the lake and the other inhabiting shallow areas. Since the two populations now differ genetically, some researchers hypothesize that each has adapted genetically to its distinct habitat.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that each of the two distinct populations of sockeye salmon has adapated genetically to their distinct habitats. This is the author’s causal explanation for the fact that the two distinct populations are different genetically, even though they both began as part of the same group of genetically uniform sockeyes.

Notable Assumptions
The author assumes there’s no other explanation for why the two groups of salmon are genetically distinct besides adaptation to their environments. This overlooks the possibility that the two populations are genetically different due to interbreeding with various other fish groups.

A
Neither of the two populations of sockeyes has interbred with the native salmon.
This helps eliminate the alternate explanation of interbreeding. In theory, the two populations might have been genetically different because one of them bred with the native salmon. (A) eliminates that explanation.
B
When the native salmon in Lake Clearwater were numerous, they comprised two distinct populations that did not interbreed.
This tells us the native salmon used to be two distinct populations. But that doesn’t shed light on the origin of the genetic differences between the sockeye salmon, which are different from the native salmon.
C
Most types of salmon that inhabit lakes spend part of the time in shallow water and part in deeper water.
Where salmon typically spend time has no impact, because we know the two populations don’t interbreed and live in different areas of the lake.
D
One of the populations of sockeyes is virtually identical genetically to the sockeyes originally introduced in 1940.
This tells us that one of the two sockeye populations is similar to the original sockeyes. But this doesn’t help establish the cause of the genetic differences between the two current sockeye populations.
E
The total number of sockeye salmon in the lake is not as large as the number of native salmon had been many years ago.
The overall number of salmon has no clear impact on the explanation for the genetic differences between the two populations.

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LSAT PrepTest 141 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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