PrepTest 158, Section 2, Question 21
A geologist recently claimed to have discovered in(51 more words not shown)
Which one of the following,(7 more words not shown)
- ANo known form(15 more words not shown)
- BSingle-celled creatures can(17 more words not shown)
- CThe material phenomena(21 more words not shown)
- DPrevious definitions of(13 more words not shown)
- EAnimals such as(12 more words not shown)
Reading the argument
Too small to reproduce in the way we expect—or too small to reproduce in any way?
The author uses reproduction as a requirement for life. A nanobe is too small to contain a reproductive mechanism, so the author concludes that it probably isn't alive at all. It's probably just part of the clay's structure.
I want to ask whether there's another way reproduction could work. Maybe a mechanism we're imagining inside each individual isn't the only possibility. We don't have to invent the biology ourselves. We need to see that the argument's rejection of life depends on treating the small individual as unable to participate in reproduction.
What we’re looking for
For a weakener, I'd look for an alternative that breaks that connection. Keep the conclusion in view: the author thinks nanobes aren't living things. A useful answer would make their small size less decisive, rather than simply tell us an unrelated fact about some other organism.
Working the answers
- A
Sexual reproduction is only a particular type of reproduction. The argument doesn't claim that life must reproduce sexually; it concerns the ability to reproduce at all. A fact about bacteria lacking the complexity for sexual reproduction doesn't address whether tiny nanobes could meet that broader requirement.
- BCorrect
An individual cell doesn't have to do everything alone. Single-celled creatures can combine into a larger structure, reproduce, and then separate again. That supplies the kind of alternative we were looking for.
Even if each nanobe is too small to contain a reproductive mechanism on its own, the author's reasoning hasn't ruled out reproduction through a larger combined structure. B doesn't prove nanobes actually do this. It shows why the small size of each individual is an inadequate basis for dismissing the possibility of life.
- C
This is tempting: something else about the same size has been described as the remains of life. But we're only told that some scientists claim those objects are fossilized bacteria. We aren't told their identification is correct. C also doesn't explain how a living thing of that size could reproduce. B provides a concrete route around the author's stated objection, while C leaves another disputed identification to be established.
- D
The fact that older definitions relied on inferior microscopes doesn't establish that this argument's reproduction requirement or size concern is wrong. We would need to know what the improved equipment revealed that matters to those claims. Simply pointing to limitations of earlier research doesn't supply that missing information.
- E
Larger animals can be simpler than smaller ones. That general comparison doesn't show how something as small as a nanobe could meet the reproduction requirement. We need a relevant possibility about reproduction, not merely a reminder that size and complexity aren't identical.
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