LSAT 149 – Section 3 – Question 08

LSAT 149 - Section 3 - Question 08

December 2017

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT149 S3 Q08	+LR	Strengthen +Streng Causal Reasoning +CausR	A 7% 156 B 3% 160 C 1% 152 D 85% 164 E 3% 158	129 141 154	+Easier	147.456 +SubsectionMedium

Over the last thousand years, plant species native to islands have gone extinct at a much faster rate than have those native to mainland regions. Biologists believe that this is because island plants have not adapted the defenses against being eaten by large land mammals that mainland plants have. Ordinarily, populations of large land mammals are not established on islands until after the island is colonized by humans.

Summarize Argument: Phenomenon-Hypothesis

Biologists hypothesize that fewer island plant species than mainland species have developed defenses to large mammals, and that’s why more island species have gone extinct. For evidence, they note that islands usually don’t have many large mammals until they’re settled by humans.

Notable Assumptions

The biologists assume island plants go extinct at higher rates than mainland plants because of large land mammals. This means assuming mainland plant species have gotten more exposure to large mammals than island species, either because large mammals were prevalent on mainlands before humans settled, or because most islands were settled more recently than mainlands. It also means assuming plants with more exposure to established large land mammals are more likely to develop defenses against them.

Most of the plant species in the world that have not yet gone extinct are native to mainland regions.

This doesn’t affect the argument. It doesn’t say islands and mainlands started out with a similar number of plant species, nor does it suggest large mammals are to blame for any discrepancy.

Many plant species that are not native to islands have become very well established on islands throughout the world.

This weakens the argument. It suggests competition from mainland plant species, not a sudden exposure to large mammals, has caused more island plants to go extinct.

Commercial development on many islands has resulted in loss of habitat for many native plants.

This weakens the argument. It suggests that commercial development, rather than large land mammals, is responsible for more island plants going extinct.

The rate of extinction of native plant species on an island tends to increase dramatically after human colonization.

This makes the biologists’ hypothesis more likely. It suggests island plant species are more likely to go extinct when large land mammals have been introduced.

Large land mammals tend to prefer plants from species native to mainland regions over plants from species native to islands.

If anything, this weakens the argument. It suggests large mammals don’t like to eat island plant species, making it less likely their introduction causes those species to go extinct.

LSAT 149 – Section 3 – Question 08

LSAT 149 - Section 3 - Question 08

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Review Results

LSAT PrepTest 149 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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