Self-study
Paleontologist: Conclusion It is widely, but falsely, held that life began in the ocean and did not exist on land until half a billion years ago. ██████ ██ ██████ ██ ████ ████ █████ ██████████ ███████ ████████████████████ █████ ██ █████ ████████ ██████ ██ ██ █████████ ██ ██████ ███ ████████ ████ ███ ██████████ ██ ████ █████ ████████ ██████████ ███ ██ ████ ████████ ████ ███ ██████ ███ ████████ ████
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that life existed on land earlier than half a billion years ago or that life began on land. This is based on the fact that traces of carbon 14 have been found throughout certain 1.2-billion-year old rocks. Carbon 14 is extracted from the atmosphere by living things and is then released when those living things die.
Notable Assumptions
The author assumes that there’s no other explanation for the presence of carbon 14 in the 1.2-billion-year-old rocks besides the existence of life. This overlooks the possiiblity that carbon 14 might get into the rock in ways that don’t require life to have existed.
19.
Each of the following, if █████ ████████ ██████████ ███████ ███ ███ ████████████████ ██████████ ███████
a
According to one ██████ ██████████ █ ███ ███████ ██ ██████ ████ █████ ██ ████ ███ ████ ████ ████ █ ███████ █████ ████
This provides additional evidence that life existed earlier than half a billion years ago.
Plausibility
Plausibility
Presenting evidence that corroborates (in Strengthen) or conflicts (in Weaken) with the author's hypothesized explanation or the predictions that follow from that explanation.
b
The severity of ██████████ ██ ███ ██████████ ██████ █████ ████ ████ ██ █████████ ███ ████ ██ █████ ██████
This provides a reason to think life did not begin in the ocean.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
c
Research suggests that ████ ████████ ██ ███ ████████████████████ █████ ████ ██ ███ ████ █████████ ██ ██████ ██████ █████ ████████ ███████ █████ █████
This strengthens by establishing that some portions of the rocks were never under water. This helps to eliminate the possiblity that all of the carbon 14 in the rocks originated from undersea creatures.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
d
The 1.2-billion-year-old rocks ████ ██████ ████ ████ ██████████ ████ █████ ███████ ██ ██████ ██ ████ ███████ ███ ████ ████████ ████ ███ ███████████
This weakens the argument by providing an alternate source of the carbon 14 besides life. (D) suggests the carbon 14 in the rocks came directly from the atmosphere rather than from a living creature.
e
Uranium testing has ████ ████ ██ ███████ ████ ███ ███ ██ ███ █████ ██ ███ ███████ ██████
This strengthens the argument by confirming that the rocks originate from earlier than half a billion years ago. If this were not true, the argument would be less convincing.
Plausibility
Plausibility
Presenting evidence that corroborates (in Strengthen) or conflicts (in Weaken) with the author's hypothesized explanation or the predictions that follow from that explanation.