PrepTest 111, Section 1, Question 22
No chordates are tracheophytes, and all members of(13 more words not shown)
The conclusion above follows logically(8 more words not shown)
- AAll members of(5 more words not shown)
- BAll members of(5 more words not shown)
- CAll tracheophytes are(3 more words not shown)
- DNo members of(5 more words not shown)
- ENo chordates are(3 more words not shown)
Reading the argument
Where did Hominidae come from? We haven't been told anything about that family.
The unfamiliar names can make the first two facts feel harder than they are. Picture two separate groups: chordates on one side and tracheophytes on the other. Nothing belongs to both. Now put every member of Pteropsida inside the tracheophyte group. That keeps every member of Pteropsida outside the chordate group.
So we can already say that no member of Pteropsida is a chordate. But the conclusion replaces chordates with Hominidae. Without a rule about Hominidae, we don't know where to place that family. It might overlap Pteropsida, or it might not.
What we’re looking for
To make the conclusion follow, I'd put all of Hominidae on the chordate side. Then Hominidae and Pteropsida would be separated by the rule we already have: no chordate is a tracheophyte. That is the missing connection to look for.
Working the answers
- A
This puts Hominidae on the tracheophyte side, alongside Pteropsida. Two groups within the same larger group might overlap. A doesn't require them to overlap, but it certainly doesn't prove that they are separate. We need a rule that rules out the overlap, not one that leaves it possible.
- BCorrect
Every member of Hominidae is now a chordate. No chordate is a tracheophyte, and every member of Pteropsida is a tracheophyte. That leaves no room for something to belong to both Hominidae and Pteropsida.
Try putting an individual in both. Its membership in Hominidae would make it a chordate; its membership in Pteropsida would make it a tracheophyte. The first premise forbids that combination. B therefore proves the conclusion.
- C
This adds a connection between two groups already mentioned in the premises. Even if all tracheophytes are Pteropsida as well as all Pteropsida being tracheophytes, we still know nothing about Hominidae. C can't establish that the new family is excluded.
- D
Being outside the chordate group leaves Hominidae free to overlap the tracheophytes and Pteropsida. This moves the family away from the very group we wanted to use to keep it separate. D doesn't establish the required separation.
- E
We can already derive this from the two premises: Pteropsida are tracheophytes, so they cannot be chordates. E repeats that existing separation without connecting Hominidae to it. The missing family remains missing.
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