LSAT 135 – Section 2 – Question 19

LSAT 135 - Section 2 - Question 19

December 2011

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT135 S2 Q19
+LR
+Exp
Weaken +Weak
Causal Reasoning +CausR
A
81%
164
B
3%
156
C
9%
159
D
4%
154
E
3%
157
137
147
157
 +Medium 146.729 +SubsectionMedium

One theory to explain the sudden extinction of all dinosaurs points to “drug overdoses” as the cause. Angiosperms, a certain class of plants, first appeared at the time that dinosaurs became extinct. These plants produce amino-acid-based alkaloids that are psychoactive agents. Most plant-eating mammals avoid these potentially lethal poisons because they taste bitter. Moreover, mammals have livers that help detoxify such drugs. However, dinosaurs could neither taste the bitterness nor detoxify the substance once it was ingested. This theory receives its strongest support from the fact that it helps explain why so many dinosaur fossils are found in unusual and contorted positions.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that “overdoses” on plants called angiosperms could’ve caused the sudden extinction of all dinosaurs. She bases this on the fact that dinosaurs couldn’t taste the plant’s bitterness or detoxify its poison, and that many dinosaur fossils are found in unusual and contorted positions.

Notable Assumptions
The author assumes that the fossils’ contorted positions are caused by poisoning from angiosperms, without considering other possible explanations for their positions.
The author assumes that, just because dinosaurs couldn’t avoid angiosperms by tasting their bitterness, they couldn’t avoid them at all. She thus assumes that dinosaurs were eating any angiosperms, a point which is never established.
She also assumes that angiosperms, which were “potentially lethal,” were deadly enough to cause the immediate extinction of all dinosaurs.

A
Many fossils of large mammals are found in contorted positions.
(A) undermines the theory by showing that there must be some other cause for the contorted shapes of large animals’ fossils. Most mammals avoided angiosperms but many still have contorted fossils. So, something other than angiosperms must have caused those fossil positions.
B
Angiosperms provide a great deal of nutrition.
This doesn’t weaken the argument because, even if angiosperms did provide nutrition, they were also poisonous. We also still don’t know that dinosaurs ate angiosperms in the first place.
C
Carnivorous dinosaurs mostly ate other, vegetarian, dinosaurs that fed on angiosperms.
By showing that some dinosaurs ate angiosperms, (C) slightly strengthens the argument. It doesn't challenge the author's theory or her assumptions that angiosperms were toxic enough to cause dinosaurs' extinction or that the contorted fossil positions were due to these plants.
D
Some poisonous plants do not produce amino-acid-based alkaloids.
This doesn’t change the fact that angiosperms do produce amino-acid-based alkaloids. So it does nothing to weaken the theory or to show that the author’s many assumptions are invalid.
E
Mammals sometimes die of drug overdoses from eating angiosperms.
We still don’t know that dinosaurs ever ate angiosperms, but (E) shows that angiosperm overdoses can cause death. So, if anything, this slightly strengthens the theory by confirming that angiosperms are poisonous enough to occasionally kill mammals.

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LSAT PrepTest 135 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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