#17 - Concept Reference, Must Be True

[Administrator]

Please post your questions below! Thank you!

[theamazingrace]

I was stuck between C and E I though both of them were right but when I looked again I found C to be the wrong answer because there was no mention of "chlorinated water systems" in the passage where Colwell tested their hypothesis. Is this right or is there another reason that I over looked.

Thanks

[Adam Tyson]

That's right, Grace! The passage did mention that scientists once believed that cholera passed only through human hosts and their waste, including waste found in unchlorinated water supplies (first paragraph), but there was no discussion of whether the bacterium could survive in chlorinated water. Since that was not mentioned or even alluded to, we can eliminate answer C. The issue in this question is of the bacterium not being culturable, which would mean it is dormant, but still infecting a human who ingests it, which would require it to wake up from its dormant state. That's answer E! Good work there.

[gabelsmith]

Is B incorrect because it is too specific? It seems to be the same as E, but adds a detail that was not mentioned in the passage.

[Robert Carroll]

gabelsmith,

That's exactly why answer choice (B) is incorrect - it's making a more specific and stronger claim than answer choice (E). If cholera can be undetectable by traditional means but still infect someone, then the body of the infected person can reasonably be inferred to be suitable for awakening cholera from dormancy. Is it therefore the same temperature as the ocean? Not necessarily. So answer choice (B) requires us to know something much more specific than answer choice (E). That's why answer choice (B) is incorrect.

Robert Carroll

[cd1010]

I struggled with this one because the passage says " Though no one knows exactly what conditions awaken V. cholerae from dormancy", and the situation that she describes after this sentence discusses how cholera cases correlate with changes in sea surface temperature. Basically, my q is, I don't get why E is supported? How do we know that the correlation regarding temperature shifts in the sea might be happening with the human body as well?

I ended up picking AC C, because I was looking for an answer that had to do with cholera's dormancy. B also does this, but it's too strong ("must"). But regarding C -- If the V. cholerae bacteria, that was undetectable, caused cholera in humans, that means that it might have been dormant in the water. To me, that was the thing that I could only say. So, then I ignored the fact that the AC has "chlorinated" because I felt like it didn't matter -- chlorinated or not, there might be dormant bacteria surviving in the water that was not detectable by traditional culture methods.

[Dana D]

Hey CD,

This question is a MBT, meaning we need to find evidence to support whatever the right answer choice is. We can't discount the word chlorinated in answer choice (C) - we have no evidence to support the idea that these bacteria can or cannot survive in chlorinated water, therefore this answer cannot be correct.

Support for answer choice (E) is in the last paragraph, which you identified - Colwell ties the changes in seawater temperature to the ability for the bacteria to spread among humans and says no one knows what awakens dormancy, indicating that awakening is possible. If the bacteria is being spread among humans and awakening is possible, than answer choice (E) is most likely to be true.

Hope that helps!