PrepTest 119, Section 2, Question 7
Although instinct enables organisms to make complex responses(52 more words not shown)
Which one of the following(8 more words not shown)
- AThe behavior of(9 more words not shown)
- BInsect behavior is(2 more words not shown)
- CAll organisms with(13 more words not shown)
- DAll organisms with(8 more words not shown)
- EOnly organisms with(11 more words not shown)
Reading the argument
The insects don't have enough neurons. Then they can't have the kind of behavior that requires those neurons.
Think about the distinction the passage gives us. Instinct is a response the organism doesn't have to reason through; imagine an animal reacting to danger without first learning what to do. Flexible behavior is the noninstinctual alternative. Learning to read helps illustrate the contrast: we aren't born already knowing how to read these sentences. The passage says flexible behavior requires a much larger supply of nerve cells.
What we’re looking for
No insect brain has enough. That rules out flexible behavior in insects under the stated rule. Since the passage uses “noninstinctual” and “flexible” for the same category, ruling that category out leaves instinctual behavior. That's the inference I'd expect to find.
Working the answers
- A
“Usually” makes a claim about how often behavior is instinctual. The passage doesn't give us that breakdown for organisms with elaborate brains. Even an organism capable of flexible behavior could still act instinctually much of the time. Ability doesn't establish frequency.
- BCorrect
Insect behavior is exclusively instinctual. Flexible, or noninstinctual, behavior requires a sufficiently large number of neurons, and insect brains cannot provide that number. Insects therefore cannot display the noninstinctual alternative described here. B stays with the group the passage explicitly rules out.
- C
A brain slightly larger than an insect's could still be too small. Knowing one brain falls below a requirement doesn't tell us that every larger brain clears it. And clearing the size requirement wouldn't itself establish that all other requirements are met.
- D
A large brain is required for flexible behavior, but we aren't told that it guarantees that capacity. There might be other requirements too. The passage lets us rule out brains that are too small; it doesn't let us approve every brain described as large.
- E
This restricts purely instinctual behavior to organisms with small brains. Why couldn't a larger-brained organism also behave entirely by instinct? The passage tells us insects cannot be flexible. It doesn't say insects and smaller organisms are the only ones without flexible behavior.
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