Self-study
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
17.
The passage suggests that if ██ ████████ ████████ ████████████ ██ ███████████ ███████ ███████ ██████████ ██████ ███████ ██ ██████ ███ ████████ █████ ████ █████ ███ ██ ███ █████████ ██ ████ ██████ ██ ██ █████
a
Human antibodies that ███████ █████ ████ ██ ██████████ ████ ████████ ████ ██████ ██ ██ ██ ██ █████ ██████
We’re not told that antibodies are connected to the process by which dormant V. cholerae can end up causing cholera in humans.
b
The human body's ███████████ ██ ███ ███████████ ███ █████ ████ █████ ██ ██████ ██ ████████ ████████ ████ █████ ███████ ██████
There’s no suggestion that the human body temperature must be the same temperature the ocean must reach to awaken V. cholerae. Maybe the human body temperature is higher and therefore can still awaken V. cholerae? Maybe the human body has the right salinity level?
c
In their dormant ██████ ██ ████████ ████████ ███ ████ ██ ███████ ██ ███████████ █████ ████████
There’s no suggestion that this would be true based on the idea of a dormant V. cholerae causing cholera once ingested by a human. What does human ingestion have to do with chlorinated water systems? We don’t know that the human ingested V. cholerae from a chlorinated water system.
d
The infected humans ███ ████ ████████ ████ ███████ ██ ████ █████ ███████ ██ █████ ██████
There’s no suggestion that this would be true based on the idea of a dormant V. cholerae causing cholera once ingested by a human. There’s no relationship between one case of cholera and a previous case of cholera in the same person.
e
The human body ██ ██ ███████████ ██ █████ ███████ ██ ████████ ████████ ███ ███████
This is supported, because if a dormant V. cholerae is ingested by a human, and the V. cholerae is able to cause cholera in the human, the V. cholerae must have awakened from its dormant state after being ingested.