PrepTest 124, Section 4, Question 21
Sometimes there is no more effective means of(444 more words not shown)
Based on the passage, the(20 more words not shown)
- AThe reproduction of(27 more words not shown)
- BThe effectiveness of(14 more words not shown)
- CThe prey population(23 more words not shown)
- DThe predator population's(19 more words not shown)
- EThe predator population(14 more words not shown)
Reading the passage
Fundamental to what? The question asks about long-term control by predators. It isn't asking whether predators must be used in every case, or how scientists can prove that a particular relationship exists.
What we’re looking for
We know Typhlodromus can keep pace with prey growth and survive when prey is scarce. I don't have an exact principle to predict yet, but the answer should explain how the control continues as prey numbers change.
Working the answers
- A
Seasonal coordination is relevant, but this specifies a predator surge just before a prey surge. That's not the pattern described. In the field example, prey numbers begin increasing and the predator population responds.
- B
The experiments verify that predation works. They aren't what makes the predator-prey relationship keep working. A population can be controlled before anyone demonstrates it in a greenhouse; evidence for the relationship and the operation of the relationship are different things.
- C
This changes the relationship. We learn that predators can survive with few prey, not that prey must survive low crop productivity to sustain predators.
- DCorrect
Control needs to respond to changing prey numbers. The account describes coordinated reproduction, survival through scarcity, and a quick predator response when cyclamen numbers rise. Together, those features let the predators keep their consumption responsive to the population they control.
- E
Shared pesticide vulnerability isn't a requirement for this control to work. Typhlodromus provide effective control even though parathion kills them without affecting their prey. Applying that chemical can disrupt the relationship; equal vulnerability isn't what enables it.
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