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Difficulty: HardCentral Ideas

Many plant species possess extrafloral nectaries—glands located outside the flowers that secrete a sugar-rich fluid. While floral nectaries function primarily to attract pollinators, evolutionary biologists initially assumed extrafloral nectaries served a similar direct reproductive role by distracting foliage-eating insects. However, ecologist Elizabeth Schuyler's research reveals a mutualistic defense mechanism: the nectar specifically recruits predatory ants, which patrol the plant and aggressively repel herbivores. Thus, rather than acting as a passive decoy to divert pests, extrafloral nectaries function as an active recruitment system that secures biotic protection, demonstrating that plant defense strategies can rely on the behavioral manipulation of mutualist partners.

Which choice best states the main idea of the text?

  1. A
    Extrafloral nectaries evolved to perform the same reproductive functions as floral nectaries by attracting pollinators.
  2. B
    Plant defense strategies are fundamentally characterized by their reliance on the behavioral manipulation of mutualist partners.
  3. Extrafloral nectaries protect plants by attracting predatory insects that deter herbivores, rather than acting as simple decoys.Answer
  4. D
    Predatory ants are the only organisms capable of defending plants with extrafloral nectaries from foliage-eating insects.

Answer

Extrafloral nectaries protect plants by attracting predatory insects that deter herbivores, rather than acting as simple decoys.
The correct answer accurately captures the main idea of the passage. The text explains that while researchers initially assumed extrafloral nectaries acted as passive decoys, ecologist Elizabeth Schuyler's research demonstrated that they serve an active role by recruiting predatory ants to defend the plant, illustrating a mutualistic defense strategy.

Step-by-Step Solution

1
Analyze the text's structure and shift in focus.
The text transitions from a past assumption (that extrafloral nectaries act as decoys) to a new finding (that they actively recruit ants for protection).
Understanding the structural transition helps identify where the author states the actual function of the nectaries.
2
Identify the author's primary conclusion.
The author concludes that extrafloral nectaries act as an active recruitment system that secures biotic protection through behavioral manipulation.
The main idea must capture this central conclusion about how extrafloral nectaries function as a defense mechanism rather than a decoy.
3
Evaluate the choices against the identified conclusion.
The option stating that extrafloral nectaries protect plants by attracting predatory insects instead of acting as decoys aligns perfectly with the text's main point.
This step ensures the selected option is accurate, supported, and not overly broad or speculative.

Key Concept

Identifying the central idea of a passage by separating primary claims from secondary details or initial assumptions.
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