Q19

[BarryM800]

I've difficulty comprehending the sentence starting line 32, which presumably provides evidence for this question.

¶2 introduced two types of toxins: brevetoxin, which was associated with P. brevis; and PCBs, which is a synthetic pollutant. The line 32 sentence in ¶3 basically says: The bodies of the dolphins showed that they were skinny, which indicated they used up a lot of their fat reserves before they died; when the fat reserves are gone, the dolphins also lose their buoyancy and insulation from the cold.

The part that gives me difficulty is "as well as releasing stores of previously accumulated synthetic pollutants, such as PCBs, which further exacerbated their condition." So it sounds to me these synthetic pollutants were also accumulated in the dolphins' blubber. Metabolizing the blubber means these dolphins also got rid of these synthetic pollutants from their system. But wouldn't that be a good thing? Why would that further exacerbate the dolphins' condition, unless the author also assumes that these accumulated synthetic pollutants are beneficial to the dolphins, possibly helping them fight off opportunistic bacterial infection? But wouldn't common sense tell us pollutants are a bad thing for our, or in this case animals', health? I just felt that we would need some outside knowledge to synthesize all these information while trying to make sense of them all.

Then, with this question, (E) states "[w]hen a dolphin metabolizes its blubber, the PCBs released may be more dangerous to the dolphin than they were, when stored in the blubber." This makes it sounds like the PCBs pollutants are bad for the dolphins after all. In addition, the "released PCBs" are even more dangerous than when they are in the dolphins' body. What does that even mean? So when the dolphins somehow got rid of these pollutants from their system, presumably releasing them into the ocean, and then swimming away, how would that even affect the dolphins anymore? Wouldn't the dolphins be better off when they're farther away from those pollutants?

Instead, I chose (D) "Opportnistic bacterial infection is usually associated with brevetoxin poisoning in bottlenose dolphins." The last sentence in ¶3 states "The combined impact made the dolphins vulnerable to opportunistic bacterial infection, the ultimate cause of death." The first sentence in ¶3 states "The research team concluded that brevetoxin poisoning was the most likely cause of the illnesses that killed the dolphins." Since taken as a fact that the ultimate cause of death is "opportunistic bacterial infection," the research team concluded that brevetoxin poisoning was the most likely cause (which is a "most" statement). Wouldn't they then assume opportunistic bacterial infection is usually associated with brevetoxin poisoning (which is also a "most" statement)?

Thanks!

[Laura Damone]

This is actually a favorite passage of mine and I hadn't looked at it in years, so thank you for asking about it, Barry!

To your first question, when toxins are stored in fat and the body metabolizes that fat, the toxins are released out into your body, not out of your body. Do you need some outside knowledge to understand this? Maybe. That might be why the writer included "which further exacerbated their condition." If there was any doubt as to whether the release of toxins was a good thing or a bad thing, this part spells it out for you. It was bad. It hurt the dolphins.

That's what makes answer choice E correct. We're told that metabolizing the fat "further exacerbated their condition." In other words, they were better off when the toxins were stored in their blubber. Metabolizing that fat released the toxins into their bodies and made them sicker.

Answer choice C tempting, but too strong. Do we know that the dolphins studied died from "opportunistic bacterial infection," yes. And we know that the researchers concluded that it was brevetoxin poisoning that paved the way, since brevetoxin was present in 8 of the 17 test dolphins. But from that can we conclude that opportunistic bacterial infection is usually associated with brevetoxin poisoning in dolphins? Not quite. The sample just isn't big or diverse enough.

Words like "usually" are always red flags in inference questions! It's very hard to provide enough evidence in a passage to justify that sort of claim.

One last thing: "A is most likely caused by B" isn't the same sort of "most statement" as "A and B are usually associated." In the first statement, we're talking about likelihood, not frequency or quantity. So even though it uses the word "most," I don't think of it as a "most statement" because it doesn't imply anything specific about quantity, frequency or proportion.

Hope this helps!