PrepTest 138, Section 2, Question 8
Scientists conjecture that certain microbes consume organic molecules(40 more words not shown)
The scientists' conjectures, if true,(11 more words not shown)
- AThe microbes' activity(12 more words not shown)
- BEvery organism that(9 more words not shown)
- CIf global warming(11 more words not shown)
- DThe microbes do(10 more words not shown)
- EA significant portion(12 more words not shown)
Reading the argument
Warmer conditions could give us more of the very microbes that contribute to warming. That sounds like a process that feeds on itself.
Follow the steps. The microbes consume organic molecules and release carbon dioxide. Carbon dioxide promotes global warming. At higher temperatures, these microbes reproduce faster, so we would expect more of their carbon-dioxide-producing activity. The warming can therefore help the microbes contribute to still more warming.
How much of a difference does this make? We haven't been told. It could be a small contribution or a large one. I want to keep that uncertainty separate from the connection we've identified.
What we’re looking for
The question tells us to assume the scientists' conjectures are true. We shouldn't reject an inference just because the passage calls them conjectures. With those statements accepted, look for the link between warmer temperatures, the microbes' activity, and further warming—without inventing a measurement of the effect.
Working the answers
- A
How much usable material is there, and how quickly will the microbes consume it? We don't know. A resource can be finite without being close to running out. Nothing establishes that depletion will soon reduce the microbes' activity.
- B
The passage concerns certain microbes. It doesn't establish the reproductive behavior of every organism that generates carbon dioxide. Other organisms could respond very differently to higher temperatures.
- CCorrect
'Exacerbated' means made worse. If warming occurs, the microbes' faster reproduction and carbon dioxide production provide a way to add to that warming. C doesn't require them to account for a large share of the problem. Even a smaller contribution can make an existing problem worse.
- D
Removing oxygen doesn't rule out removing other elements too. We are told one thing these microbes take from the atmosphere, not that it is the only thing. D adds an exclusion the scientists never state.
- E
Producing carbon dioxide doesn't establish a significant share of all the carbon dioxide in Earth's atmosphere. We'd need information about the amount these microbes produce compared with other sources. The passage supports a contribution, not this claim about its size.
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