LSAT 141 – Section 4 – Question 15

LSAT 141 - Section 4 - Question 15

September 2014

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT141 S4 Q15
+LR
Resolve reconcile or explain +RRE
Causal Reasoning +CausR
A
82%
164
B
12%
157
C
2%
153
D
1%
157
E
3%
157
139
148
157
 +Medium 147.542 +SubsectionMedium

Hine’s emerald dragonflies are an endangered species that live in wetlands. The larvae of these dragonflies can survive only in the water, where they are subject to predation by several species including red devil crayfish. Surprisingly, the dragonfly populations are more likely to remain healthy in areas where red devil crayfish are present than in areas without red devil crayfish.

"Surprising" Phenomenon
Why are the dragonfly populations more likely to remain healthy in areas where red devil crayfish are present than in areas without red devil crayfish, even though the dragonfly larvae can survive only in water, and those larvae can be eaten by red devil crayfish when they are in water?

Objective
The correct answer should tell us something beneficial for the dragonflies from being in areas with the red devil crayfish, or something negative from being in areas without red devil crayfish.

A
Red devil crayfish dig chambers that remain filled with water even when the surrounding wetlands dry up.
This is a benefit for the dragonfly from being in areas with red devil crayfish. Without the water chambers created by the crayfish, larvae might not be able to survive. This may be why dragonfly populations are higher in areas with the crayfish despite the extra predation.
B
Red devil crayfish present no threat to adult Hine’s emerald dragonflies.
But the crayfish can still eat the dragonfly larvae. We’d still expect the dragonfly population to be better off without the red devil crayfish.
C
The varied diet of the red devil crayfish does not include any animal species that prey on dragonfly larvae.
If the crayfish eat the larvae, and don’t eat anything that preys on the larvae, that’s worse for the larvae. We’d expect the dragonfly population to be better off without the red devil crayfish.
D
Red devil crayfish are found in many more locations than Hine’s emerald dragonflies are.
The number of places the crayfish is found doesn’t tell us anything beneficial about the crayfish for the dragonfly population. We still don’t know why the dragonfly population is higher in areas with the crayfish than in areas without.
E
Populations of red devil crayfish in a wetland do not drop significantly if the local population of Hine’s emerald dragonflies dies out.
This suggests crayfish might eat other things besides the dragonflies. But they can still eat dragonfly larvae. So, we’d still expect the dragonfly population to be better off without the red devil crayfish.

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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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