Self-study
To reduce the mosquito population in a resort area, hundreds of trees were planted that bear fruit attractive to birds. ████ ███ ██████ ██ ███ █████ ████████ ████ █████████ █ ███████ ██ ████ ███████ ███ ███████ █████████ ███ ██████ ████ ██████████ ██ ███ █████ ██ █████████ ███ █████ ███ ████ ███████████ ████████ ███ ████████ ██ ███ █████ █████ ███ ███ ████ ████████ ██ ███ ████████ ███████
"Surprising" Phenomenon
Why did planting trees that attracted birds end up increasing the mosquito population, even though the trees did attract birds and the birds did eat many mosquitoes?
Objective
The correct answer should describe an effect of the trees or of the birds attracted to the area that could result in an increase in mosquitoes.
15.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ██████████ ███████████ ███████
a
Most of the ███████ ██ █████ ████ ████ █████████ ██ ███ █████ ████ ████ ███████ ███ ███ ███ ███████████
The stimulus tells us “the birds at many mosquitoes.” Even if most of the bird species didn’t eat mosquitoes, we still know many mosquitoes were eaten by birds. So, we’d still expect the mosquito population to go down.
b
The species of █████ ████ ████ █████████ ██ ███ ████████ ██████ ██ ███ █████ ██ ███ █████ ████ ████ ███████ ███ ███ ███ ███████████
The stimulus tells us “the birds at many mosquitoes.” Even if the species that had the most birds didn’t eat mosquitoes, we still know many mosquitoes were eaten by birds. So, we’d still expect the mosquito population to go down.
c
The birds attracted ██ ███ ████ ██ ███ █████ ███ ████ ████ ███████ ████ ████ ██ ██████████ ████ ████ ███ ███████████
If there were fewer insects that preyed on mosquitoes, that means fewer mosquitoes would die to those insects. This is how the net effect of the birds could have been an increase in mosquitoes, even if the birds did eat many mosquitoes.
d
Since the trees ████ ████████ ███ ██████ █████████████ ███ ████ █████ ████████ ███ █████ ███████ █████ ██ ████ ████████ ███████████ █████
This deepens our confusion. If there has been below-average rain after the trees were planted, we’d expect lower mosquito populations. But the mosquito population increased.
e
Increases and decreases ██ ████████ ███████████ ████ ██ ██████ █ ████████ ████████
But if we introduce trees that attract birds, and the birds eat many mosquitoes, we’d still expect mosquito population not to increase. Whatever happens generally concerning mosquito populations doesn’t impact what we’d expect to happen after introducing the trees.