Self-study
P1
Naturalists have long studied the ability of North American forest birds to survive extremely cold overnight temperatures in winter. ███
Phenomenon ·
Birds can survive extremely cold winter night temperatures
Presumably, the question is how they can do this?
Examples of Phenomenon and Explanation ·
Nuthatches, chickadees, and grosbeaks
Nuthatches sleep in cavities to retain heat; Chickadees induce torpor to save energy; Grosbeaks eat a lot of fatty seeds to power shivering.
Unexplained Phenomenon ·
Kinglets
How do kinglets stay warm?
P2
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1st Unexplained Aspect of Phenomenon ·
Tiny size
Kinglets' small size means they rapidly lose heat and hence should have to consume and burn more calories to maintain temperature.
Partial Explanation ·
Insulating feathers
P3
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2nd Unexplained Aspect of Phenomenon ·
Insect diet
We already know that kinglets are supposed to have to eat more food but they only eat insects that they catch during the short winter day. How can they be constantly catching and eating enough insects?
P4
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Partial Explanation ·
Kinglets store fat well
Remaining Unexplained Phenomenon ·
Fat stores only accounts for half the energy they need to survive
Hypothesis ·
Perhaps they also induce torpor?
No evidence for this.
Hypothesis ·
Perhaps they cluster together?
We know that other birds do this. Perhaps at night, kinglets cluster to retain heat.
Passage Style
Phenomenon-hypothesis (RC)
Single position
1.
Which one of the following ████ ██████████ ██████ ███ ███████ ████ ██ ███ ████████
a
Kinglets are able ██ ███████ ███ ███████ ██████ ██████ ███████ █ █████ ███████████ ███ ████████ ████ ██████ ████ ████ ██████████ ██ ███ █████████████
(A) is the phenomenon. But (A) doesn’t say anything about potential hypotheses to explain the phenomenon.
b
Researchers have tested ███████ ████████ ██ █████ ████████ ██ ██████ ███ ████████ ██ ███ ████████ ███████ ████ ███ █████████████
Unsupported, because the passage never establishes that researchers have “tested” theories regarding kinglets.
c
Kinglets are unique █████ █████ █████ ███ ██ █ ████████ ████ ██ █████████ ███ ████████████ ████ ██ █████ ████ ██ ██████ ██████
Unsupported, because we have no reason to think kinglets are “unique” among small birds in their ability to survive extremely low temperatures. In fact, we know from P1 that at least some other birds can survive cold temperatures — nuthatches, chickadees, and grosbeaks.
d
The kinglet's tiny ████ ███████████ ███ ████████ ██ ███████████ ██ ███████ ███ ██ ████████ ███ █████████ ███ ████████████ ██ ██████ ███████
Unsupported. The author doesn’t suggest that the kinglet’s small size makes observing them more difficult.
e
Researchers do not ███ █████ ██████████ ███ ██████████ ███ █████████████ ███████ ████ █████ ████████ ██ ███████ ███ ███████ ██████ ███████
This is the best answer, because it at least relates to the hypotheses in the last paragraph. We have a partial explanation for how kinglets stay cold, but we don’t yet fully understand how they are able to survive.