Self-study
passage 1
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
Single position
4.
The passage suggests that the ██████ ████ ██████ ███████ ███ ██████████ ████ ██████ ██ ████████ ███████ ████████ ██ ████ ██████ ██████ ██
a
almost certainly true, █████ ███ █████ ████████████ ████ ████ ██████████
b
feasible given that ████████ █████ ██ ██████ ██████ ███ ███
c
a possibility that, ██████ █████████ ██ ███ ████ ██████ ████ ██ ███████
d
well established by █ ██████ █████ ██ ██████████
e
the hypothesis most ██████ █████████ ██ ███ ██████████ █████████