LSAT 102 – Section 3 – Question 04

LSAT 102 - Section 3 - Question 04

June 1998

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT102 S3 Q04
+LR
+Exp
Weaken +Weak
Causal Reasoning +CausR
A
9%
160
B
1%
165
C
20%
160
D
66%
167
E
3%
158
147
157
168
 +Harder 147.613 +SubsectionMedium

J.Y.’s explanation

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Scientists analyzing air bubbles that had been trapped in Antarctic ice during the Earth’s last ice age found that the ice-age atmosphere had contained unusually large amounts of ferrous material and surprisingly small amounts of carbon dioxide. One scientist noted that algae absorb carbon dioxide from the atmosphere. The scientist hypothesized that the ferrous material, which was contained in atmospheric dust, had promoted a great increase in the population of Antarctic algae such as diatoms.

Summarize Argument: Phenomenon-Hypothesis
The scientist hypothesizes that the ferrous material promoted a great increase in the population of Antarctic algae. She supports this by noting that algae absorb carbon dioxide from the atmosphere.

Notable Assumptions
The scientist assumes that more ferrous material leads to more algae, which in turn absorbs carbon dioxide. This means she assumes that the relationship isn’t the reverse (i.e. more algae leads to more ferrous material), and also that there isn’t some other, hidden cause that’s actually responsible for the amount of algae. The scientist also assumes that algae was actually present in Antarctica at this time, in quantities sufficient to draw her conclusion.

A
Diatoms are a microscopic form of algae that has remained largely unchanged since the last ice age.
Diatoms are just one example of algae, and this fact doesn’t change what we think about algae in general. We need to weaken the connection between ferrous material and algae.
B
Computer models suggest that a large increase in ferrous material today could greatly promote the growth of oceanic algae.
If anything, this supports the scientist’s argument. We want to weaken this same connection.
C
The dust found in the air bubbles trapped in Antarctic ice contained other minerals in addition to the ferrous material.
Were these other minerals the cause of the algae? As it is, we don’t know enough about them to say they weaken the argument.
D
Sediment from the ocean floor near Antarctica reflects no increase, during the last ice age, in the rate at which the shells that diatoms leave when they die accumulated.
At least one type of algae didn’t actually increase at all in Antarctica during the period in question. This suggests the ferrous material wasn’t causing algae growth.
E
Algae that currently grow in the oceans near Antarctica do not appear to be harmed by even a large increase in exposure to ferrous material.
The scientist claims that ferrous material causes algae growth. This doesn’t weaken that claim, and in fact defends against a possible weakener—that too much ferrous material is harmful to algae.

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LSAT PrepTest 102 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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