LSAT 129 – Section 3 – Question 24

LSAT 129 - Section 3 - Question 24

June 2009

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT129 S3 Q24
+LR
Sufficient assumption +SA
Link Assumption +LinkA
A
1%
155
B
1%
155
C
91%
165
D
5%
155
E
1%
154
141
148
154
 +Medium 146.07 +SubsectionMedium

It is widely believed that lancelets—small, primitive sea animals—do not have hearts. Each lancelet has a contracting vessel, but this vessel is considered an artery rather than a heart. However, this vessel is indeed a heart. After all, it strongly resembles the structure of the heart of certain other sea animals. Moreover, the muscular contractions in the lancelet’s vessel closely resemble the muscular contractions of other animals’ hearts.

Summary
The author concludes that lancelets have hearts, because they have a vessel that is similar to other hearts in their structure and contractions.

Missing Connection
The conclusion is about having a heart, but we aren’t given information on what qualifies as having a heart. The support only comes from the structure and behavior of the lancelet’s vessel bearing similarity to other hearts. We can make the argument valid if we know for sure that one or both of these qualities (structure or behavior) having commonality with other hearts is enough to qualify as having a heart.

A
Only animals that have contracting vessels have hearts.
This is switching sufficient and necessary. (A) can only support a conclusion about having contracting vessels or, through contrapositive, not having a heart. We need something that would support a conclusion about having a heart.
B
Some primitive animals other than lancelets have what is widely held to be a heart.
Irrelevant. Just because other animals with one similarity to the lancelet have a heart, it does not strengthen the argument that lancelets have a heart. Even in a Strengthen question, this answer is problematic.
C
A vessel whose structure and actions closely resemble those of other animal hearts is a heart.
This links the vessel of the lancelet to a conclusion about having a heart. This means the traits of the lancelet’s vessel qualify for having a heart.
D
For a vessel in an animal to be properly considered a heart, that vessel must undergo muscular contractions.
Similar to (A), a reversal of what we need. We need for “properly considered a heart” to be a necessary condition. We need to conclude that something has a heart, and we cannot do that when it is in the sufficient condition.
E
No animal that has a heart lacks an artery.
Phrased another way, this is “If an animal has a heart, then it has an artery.” This has the same issue as (A) and (D)— We need to conclude that something has a heart, and we cannot do that when it is in the sufficient condition.

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LSAT PrepTest 129 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Reading Comprehension

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