LSAT 155 – Section 2 – Question 03

LSAT 155 - Section 2 - Question 03

November 2019

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT155 S2 Q03	+LR	Strengthen +Streng Causal Reasoning +CausR Eliminating Options +ElimOpt	A 1% 144 B 97% 160 C 0% 146 D 0% 143 E 1% 147	125 132 138	+Easiest	145.934 +SubsectionMedium

Biologist: DNA analysis shows that Acacia heterophylla, a tree native to the Indian Ocean’s Réunion Island, is descended from the Hawaiian tree Acacia koa. Some think this occurred because A. koa seeds floated from Hawaii to Réunion, but that explanation is implausible, since the seeds will not germinate after being soaked in seawater. Moreover, both trees grow in the mountains, not near the shore. Seabirds sometimes carry seeds great distances, so they probably caused the dispersal.

Summarize Argument: Phenomenon-Hypothesis

The biologist hypothesizes that seabirds brought Acacia koa seeds from Hawaii to Réunion Island. He supports this by noting that seabirds can carry seeds over long distances, and by pointing to DNA evidence that shows that Acacia heterophylla trees on Réunion Island are descended from the Hawaiian Acacia koa. He argues that it’s unlikely that the seeds floated to Réunion Island because they won’t germinate after being soaked in seawater and because both trees grow in the mountains, not near the shore.

Notable Assumptions

The biologist assumes that the seeds couldn’t have floated across the ocean without being soaked in seawater. He also assumes that his hypothesis is the most likely, without considering whether there actually are seed-carrying seabirds on these islands, or whether another explanation, like humans transporting the seeds, is more likely.

A. koa branches carrying seeds can remain afloat for prolonged periods of time.

This supports the alternative hypothesis that the seeds floated across the ocean. It doesn’t support the biologist’s hypothesis that seabirds carried the seeds to Réunion Island.

There are mountain-nesting seabird species common to Réunion and Hawaii.

This strengthens the biologist's argument by addressing the assumption that seabirds actually live on both Réunion and Hawaii and are likely to carry seeds between the mountains. If mountain-nesting seabirds are common to both islands, his hypothesis becomes much more likely.

A. koa is thought to be descended from Acacia melanoxylon, a tree native to eastern Australia.

The argument is only concerned with the fact that A. heterophylla is descended from A. koa. It doesn’t matter what tree A. koa is descended from.

Ocean currents have sometimes carried buoyant objects from Hawaii to Réunion.

Like (A), this supports the alternative hypothesis by implying that the seeds could’ve floated from Hawaii to Réunion. Instead, we need an answer choice that strengthens the biologist’s hypothesis that seabirds carried the seeds between the islands.

Many seabird species return to land very infrequently, and often do so only to breed.

Irrelevant— we don’t know whether the “many seabirds species” in (E) are living on Réunion or Hawaii. Even if they are, this weakens the argument by suggesting that the seabirds rarely return to land to disperse the seeds.

LSAT 155 – Section 2 – Question 03

LSAT 155 - Section 2 - Question 03

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Review Results

LSAT PrepTest 155 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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