Self-paced
P1
For nearly a century after the discovery in the 1880s that a bacterium, . ██████ █████████ ██████ ████████ ██████████ ████████ ████ ██ ████████ ██ ███ ██████████ ███████ ████ ███ █████ █████ ███ ████ █████████ █████████ ████████ ████ ███ ████████ ██████ ███████ ██████████████ ██ █████ ██████ ██ ████ ███ █████████████ █████ █████████ ███
Scientists' belief ·
Vibrio cholerae (VC), which causes cholara, travels only by human hosts
VC epidemics occur when bacteria spreads through human waste.
Puzzling phenomenon ·
VC pops up in places we thought it had been eliminated
And, where does it go in between epidemics?
P2
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Colwell's discovery ·
Found VC in Chesapeake Bay
Others were skeptical because they thought VC couldn't survive without a human host, and there were no cholera epidemics since 1911.
Colwell's hypothesis ·
VC can survive in seawater, and can't always be detected by traditional methods
Traditional methods involved growing bacteria in a petri dish. Perhaps we can't do this with VC.
Testing Colwell's hypothesis ·
New detection method finds VC in water
Used this method near New Orleans and in Asia. Method involves an antibody that produces light if VC is present.
P3
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Additional findings ·
VC can become dormant and stop reproducing
That's why it sometimes can't be cultured. In this dormant state, VC can survive away from humans. We don't know what awakens VC from a dormant state, but it might be changes in seawater temperature or salinity (saltiness).
Passage Style
Phenomenon-hypothesis (RC)
Single position
20.
The passage suggests that Colwell ████ ██████ █████ █████ ███ ██ ███ █████████ █████ █████████ ██ █████████
a
In most cases, ██ ████████ ████████ ██ ███ ██████ ██ ███ █████████ ███ █████ ██████ ███ ██████ ████ ███████ ███ ██████
No support for Colwell thinking that “most” cases involve V. cholera traveling through the ocean. Although Colwell does believe that the bacteria can live in the ocean, we have no reason to think she believes this has been the method of spreading in over half of cases that V. cholera has traveled to new locations.
b
In most cases, ██ ████████ ████████ █ █████ ████ ██ █████ ██ ██████ ███ ██████ ████ ████████ ██ █ ██████████ ██████
c
Cholera outbreaks are █████ ██████ ██ ███ ████████████ ██ ██████ ██ ████████ ████████ ████ █ ███ █████████ ███ ██████ ██ ██ ████████ █████████ ████ █████████
Too strong to be supported. We have no reason to think Colwell believes cholera is “never” spread to a new location when it’s already active.
d
Use of Colwell's ███ █████████ █████████ ██ ███ █████ ███████ ███ ████████ ████ ███ ██████████ ███ █████ ████ ████████ ███ ████████ ██ ██ █████████
Supported, because she believes her new method can detect V. cholera when traditional methods can’t. She likely believes this new method would have discovered V. cholera in the Chesapeake, since she believed
e
Water samples from ███████ ███████ ██████████ █████ ██ █████████ ██ █████████ ███ █████████ ██████████ █████ ██████ ███ ████████ ██ ██ █████████
No support for the belief that water samples from coasts “throughout” Asia would show presence of V. cholera. Asia’s a huge continent with a lot of coastline; we have no reason to think Colwell believes most or all of the coastal areas have V. cholera. The fact that we conducted some tests in Asia, or that the Bay of Bengal has had cholera cases doesn’t provide support, because this evidence doesn’t necessarily extend to other coastal regions of Asia.