LSAT 138 | Section 1 | Reading Comprehension: Q10

RC Question 10 Explanation

DISCUSSION: Primary substances are only mentioned in part of the first paragraph. They’re mentioned to provide contrast with secondary substances. This information clarified what secondary substances are and are not.

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1. We’re told that primary substances are required for plant growth (paragraph 1), but we’re not told how they help growth.
2. CORRECT. By mentioning primary substances, the passage clarified what secondary substances are not. 
3. No. The distinction is between selecting characteristics that help pollination, and selecting characteristics that defend against predators. That’s all done with secondary substances. We’re not told whether insects have a role in selecting primary characteristics.
4. The secondary substances have ‘a multitudinous array of chemical’ (paragraph 1). We have no idea which chemicals are in primary substances. Maybe it’s just a few.
5. Plants use secondary substances to adapt, not primary substances. See paragraph 2.