#15 - Researcher: Salmonella bacteria are a major cause of

[Administrator]

Complete Question Explanation

Resolve the Paradox. The correct answer choice is (E).

In this stimulus we are told that chicks treated to reduce salmonella end up a week later with more of some kind of bacteria than untreated chicks. We are asked to help explain the situation. As with most Resolve questions, we should be thinking about what caused this situation to occur. Our prephrase should be about the treatment somehow causing the difference in bacteria levels, since the treatment came before the difference in the two groups showed up.

Answer choice (A): You may be drawn to this answer, thinking that the bacteria is around because the treatment hasn't begun to take effect yet, but this is a trap. The delayed time to administer the treatment actually tells us nothing about what happens AFTER the treatment is administered, or why treated chicks have higher levels than untreated ones.

Answer choice (B): There is nothing in this answer that gives us the cause of the higher levels of bacteria only in the treated chicks.

Answer choice (C): While this is good news for chicks trying to stay healthy, it gives us no cause for, or explanation of, the higher level of bacteria in treated chicks relative to untreated chicks.

Answer choice (D): This answer appears in some ways to make the paradox even more confusing. Untreated chicks have less bacteria than treated ones, but still get sick more often than the treated ones? As this potentially adds more confusion, and does not provide a cause or other explanation for the difference in the groups, it is a loser.

Answer choice (E): This is the correct answer choice. Here we have our causal explanation, although you may find it to be subtle. If this answer is true (and the stem says we are to treat it as if it is), then the salmonella was causing lower levels of bacteria prior to the treatment. Once the salmonella was killed off in the treated chicks, the previously inhibited bacteria had a chance to start growing in those chicks, while in the untreated chicks it remained lower due to still being inhibited by salmonella. Paradox resolved!

[lauriesnyder]

Hi, can you please explain why E is correct? I was between E and A and chose A. Thank you!

[Adam Tyson]

I can sure try, lauriesnyder! This stimulus presents us with a paradox - treated chicks had a lower level of Salmonella infection, but a higher count of some kind of bacteria (yuck). We need an answer that explains how those two could coexist. Most Resolve the Paradox answers are about providing a cause for the odd situation, and this is no different. So, what might cause MORE bacteria in chicks that have LESS Salmonella? I can think of two prephrases:

1. The bacteria is there as part of the treatment, like a vaccine perhaps. The bacteria is the thing that killed the Salmonella, so having more of this kind of bacteria CAUSES less Salmonella.

2. The lack of Salmonella CAUSED the increase of this type of bacteria. Maybe Salmonella normally inhibits it, and with the Salmonella gone there is nothing to stop the growth of the bacteria? Where the cause is absent, the effect is absent? This bacteria thrives only in a Salmonella-free environment?

#2 here turns out to be what answer E is telling us, and it's why E resolves the paradox. The treatment got rid of the Salmonella, which allowed this nonvirulent (non-poisonous or non-dangerous) bacteria to grow.

Answer A doesn't tell us why the bacteria is higher in the treated chicks than the untreated ones. The treatment takes a while to complete, but we still have this higher concentration of bacteria AFTER the treatment than without it. What caused the increase? This answer still leaves us wondering about that, and so it fails to resolve the issue for us.

Look for good causal answers in Resolve questions! Something made this odd situation happen, so find that cause!