PrepTest 107, Section 1, Question 11
It is well known that many species adapt(108 more words not shown)
Of the following, which one(9 more words not shown)
- AThe Earth would(14 more words not shown)
- BBy altering their(19 more words not shown)
- CImproving their own(16 more words not shown)
- DThe extent of(17 more words not shown)
- ESpecies such as(29 more words not shown)
Reading the argument
Changing yourself to fit an environment is different from changing the environment to suit you. A house, for example, lets people change the conditions they live in rather than simply endure the weather.
But is that sort of environmental change limited to the most highly evolved species? I immediately think of beavers building dams and ants making nests.
The author also challenges the restriction, though the example here is much less direct: plankton release a gas, the gas contributes to cloud formation, the clouds reflect sunlight, and the resulting cooling benefits the plankton.
My first reaction is that releasing a gas seems different from deliberately building a house. Is the change intentional, or just a useful by-product? That's a distinction worth noticing, but the stated claim doesn't require an intention. The example is supposed to show that organisms can change their surroundings in a way that helps them survive.
What we’re looking for
The main-point question asks what this elaborate example supports. The answer isn't simply that plankton cool the Earth. That is the example's result, which supports the broader correction: beneficially altering the environment isn't limited to the most highly evolved species. Follow what supports what. The final 'thus' introduces a conclusion about the example, not the overall point.
Working the answers
- A
This focuses on what would happen if the plankton disappeared. The passage describes their cooling effect but doesn't establish how much warmer Earth would become without them. More importantly, even a supported statement about that effect would remain part of the example, not the general point it supports.
- B
The author says the cooling benefits the plankton, not the Earth as a whole. Conditions that favor one organism don't automatically favor every other organism. B adds that broader benefit and still focuses on the example instead of the restriction being challenged.
- CCorrect
This states the general claim the plankton example is meant to establish. The author introduces a common assumption, rejects its limitation to the most highly evolved species, and uses plankton to illustrate why that limitation is mistaken.
- D
Cloud formation belongs to the explanation of how plankton affect their environment. The author isn't mainly trying to explain what determines cloud cover. Even if we accepted this statement about plankton quantity, it would leave out the larger point about which species can alter their surroundings for their own benefit.
- E
The passage doesn't compare how much harm different species cause to other organisms. It only needs the plankton's environmental effect to benefit the plankton themselves. A comparison of effects on other species is a new claim, not the main conclusion.
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