PrepTest 122, Section 3, Question 24
Every culture that has adopted the cultivation of(465 more words not shown)
The author's reference to "(22 more words not shown)
- AIt indicates why(23 more words not shown)
- BIt supports the(23 more words not shown)
- CIt supports the(16 more words not shown)
- DIt explains why(18 more words not shown)
- EIt advances a(17 more words not shown)
Reading the passage
Don't stop at the phrase by itself. Excluding all atmospheric gases protects rubisco from oxygen, but it also means carbon dioxide cannot enter those cells as a gas. We still need carbon dioxide for sugar production.
What we’re looking for
That's why the next step matters: convert it into a nongas form that can get in. The reference sets up the need for that workaround.
Working the answers
- A
The previous paragraph mentions atmospheric conditions, but this phrase doesn't explain how those conditions cause oxygen buildup. It describes which gases the protected cells exclude.
- B
Excluding other gases doesn't establish that they also interfere with photosynthesis. Carbon dioxide is the obvious counterexample to that reasoning: it is excluded as a gas even though the plant needs it.
- C
We aren't told that non-C-4 plants use a wider collection of atmospheric gases. C-4 plants still use carbon dioxide; they get it into the protected cells in a different form.
- DCorrect
Carbon dioxide can't enter directly as a gas, so it first becomes the C-4 intermediary. The phrase explains the need for the transformations that follow, rather than introducing another harmful gas.
- E
Keeping gases out of particular cells doesn't establish that oxygen levels throughout C-4 plants remain constant. No such constant-level claim is made.
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