LSAT 148 – Section 4 – Question 25

LSAT 148 - Section 4 - Question 25

December 2016

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT148 S4 Q25
+LR
Weaken +Weak
Causal Reasoning +CausR
A
3%
158
B
26%
160
C
9%
160
D
41%
166
E
21%
162
157
167
176
 +Hardest 147.694 +SubsectionMedium

This is not what the question is talking about but it's very cool:

Scientist: A small group of islands near Australia is inhabited by several species of iguana; closely related species also exist in the Americas, but nowhere else. The islands in question formed long after the fragmentation of Gondwana, the ancient supercontinent that included present-day South America and Australia. Thus, these species’ progenitors must have rafted on floating debris across the Pacific Ocean from the Americas.

Summarize Argument: Phenomenon-Hypothesis
The scientist hypothesizes that the iguanas’ ancestors reached the islands near Australia by rafting from the Americas. As support, he points out that the only closely related species that currently exist are located in the Americas. He also notes that the islands first formed in isolation, away from any land masses, which implies that species could only exist there now if their ancestors had somehow arrived from elsewhere.

Notable Assumptions
The scientist assumes that the closely related species in the Americas have the same ancestor as the island iguanas. He further assumes that this common ancestor has only ever lived in the Americas and nowhere else.

A
A number of animal species that inhabit the islands are not found in the Americas.
The argument is only concerned with the origins of the iguana species. The potential origins of any other species are irrelevant.
B
Genetic analysis indicates that the iguana species on the islands are different in several respects from those found in the Americas.
The scientist doesn’t suggest or assume that the island iguanas are the same species as the American ones. His argument is that they merely share the same ancestor, and that this ancestor rafted from America to the islands. They may have evolved differently since that ancestor.
C
Documented cases of iguanas rafting long distances between land masses are uncommon.
That documented cases are uncommon does not mean that this situation was impossible or even unlikely at the time.
D
Fossils of iguana species closely related to those that inhabit the islands have been found in Australia.
This suggests that the island iguanas’ ancestor may have arrived from Australia, rather than from the Americas.
E
The lineages of numerous plant and animal species found in Australia or in South America date back to a period prior to the fragmentation of Gondwana.
The argument is only concerned with the origins of the island’s iguana species. The potential origins of other species in other locations are irrelevant.

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LSAT PrepTest 148 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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