Self-study
Zoologist: Plants preferentially absorb heavy nitrogen from rainwater. █████ ████████ ████████████ ███████ ████████████ ██ ███ ███████ ██ ███████████ ███ ███████ ████ ███ ████ ██ ████ ███████ ████ ██████ ██████████████ ██ █████ ████████ ██ █████ ██████ ████████ ██ ████████ ████ ███████ ████ ████████ ████ █████ ██ ███ ███ ███ ████ █████ ███████ ████ ███████████ █████ ███ █████████████ ██████ ███ ███ ██████ ██ █████ ████████ ███████ ██ █████ ███████ ████ ██████████ █████ ███ ███████████ ████████ ████ █████ ████ ███ ███████████ ███████████
Summarize Argument: Phenomenon-Hypothesis
The zoologist hypothesizes that prehistoric European cave bears were not exclusively herbivores. This is supported by observations about bears’ heavy nitrogen levels, which are higher in meat-eating animals. Bone samples from cave bears contained heavy nitrogen levels as high as those in blood samples from modern, meat-eating bears.
Notable Assumptions
The zoologist assumes that heavy nitrogen levels in animals’ bones and blood are similar. The zoologist also assumes that heavy nitrogen levels did not change over time in the prehistoric bear samples, and that heavy nitrogen levels in the ecosystem back then were comparable to current levels.
23.
Which one of the following, ██ █████ █████ ████ ██████████ ███ ███████████ █████████
a
Plants can also ██████ █████ ████████ ████ █ ███████ ██ ███████ █████ ████ ██████████
This is irrelevant. The argument has already established that plants absorb heavy nitrogen, so the exact source of the heavy nitrogen doesn’t matter.
b
The rate at █████ █████ ████████ ███████████ ██ ███ █████ ██ ███ ███ ██████████ ███ ██ ████████ ████ ███████ ██ █████ ██████
This is irrelevant, since the argument doesn’t make claims based on the rate of accumulation of heavy nitrogen in tissue, only the concentration of heavy nitrogen.
c
The same number ██ ███████ ███ █████ ████ ███████████ █████ ██ ███ █████ ████ ███ ███ ████ ██████
This is irrelevant, because the exact number of samples doesn’t really make a difference. Either there were enough samples to be representative or there weren’t—either way, it would be equally possible to have the same number of samples.
d
Bone samples from ███████████ █████ ███ █████████████ █████ ███████ ███ ████ ██████ ██ █████ ████████ ██ ██ █████ █████ ████████
This strengthens by providing a closer comparison between cave bears and modern bears. If modern bears’ heavy nitrogen levels are identical between blood and bone, it’s more reasonable to draw conclusions by comparing cave bears’ bones and modern bears’ blood.
e
The level of █████ ████████ ██ ███ █████ ██ ███ ████ ███ █ █████████████ ████ ██ ███ ████ ██ ████ ██ ███ █████ ██ ███ █████ ███████████ █████
This is irrelevant, since we can already be confident that the heavy nitrogen level in the modern bear samples is representative of a diet that includes meat.