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Question

Difficulty: EasyExplicit Detail and Information Retrieval

For decades, plant biologists conceptualized forest ecosystems as assemblages of individual organisms locked in direct competition for light, water, and soil nutrients. However, recent advances in isotope tracing and molecular ecology have revealed that beneath the forest floor lies a vast, interconnected subterranean network facilitated by mycorrhizal fungi. These fungal hyphae physically connect the root systems of separate trees—even those belonging to disparate species—forming what researchers term common mycorrhizal networks (CMNs). Through these conduits, carbon, nitrogen, and phosphorus are actively redistributed between individuals. Field studies have demonstrated that mature canopy trees, possessing substantial photosynthetic capacity, frequently transfer surplus carbohydrates to shaded understory seedlings that would otherwise perish from light limitation. In addition to nutrient transfer, CMNs serve as biochemical signaling pathways: when an herbivore attacks a donor plant, the damaged plant transmits chemical defense warnings through the fungal network to neighboring conspecifics, prompting them to synthesize protective enzymes before infestation occurs. While early interpretations characterized this mutualism as purely altruistic cooperation, evolutionary biologists now emphasize that the fungal symbionts mediate these resource exchanges primarily to maximize their own carbon acquisition and metabolic stability.

According to the passage, which of the following is an explicit effect of transmitting chemical defense warnings through common mycorrhizal networks when a plant is attacked by herbivores?

  1. A
    Shaded understory seedlings immediately redirect surplus carbohydrates back to mature canopy trees.
  2. B
    Fungal hyphae permanently sever physical connections with neighboring trees belonging to disparate species.
  3. Neighboring plants of the same species are stimulated to produce protective enzymes prior to being infested.Answer
  4. D
    Neighboring conspecifics release airborne pheromones to deter predatory insects across the canopy.
  5. E
    The donor plant ceases all nutrient absorption through its root system to isolate the infection.

Answer

Neighboring plants of the same species are stimulated to produce protective enzymes prior to being infested.
The passage explicitly states that when an herbivore attacks a plant, warning signals transmitted through the network prompt neighboring conspecifics (members of the same species) to synthesize protective enzymes before infestation occurs. The correct option directly paraphrases this explicit fact.

Step-by-Step Solution

1
Locate the explicit discussion of herbivore attacks and warning signals in the passage.
Identified the sentence: 'when an herbivore attacks a donor plant, the damaged plant transmits chemical defense warnings through the fungal network to neighboring conspecifics, prompting them to synthesize protective enzymes before infestation occurs.'
Explicit detail questions require finding the exact textual reference corresponding to the key terms in the question stem.
2
Match the consequence described in the passage with the paraphrased answer choice.
The phrase 'neighboring conspecifics' corresponds to 'neighboring plants of the same species', and 'synthesize protective enzymes before infestation occurs' corresponds to 'produce protective enzymes prior to being infested'.
Direct retrieval confirms the accurate paraphrase of the explicit text.

Key Concept

Explicit retrieval and paraphrasing of directly stated textual details
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Topics

Explicit Detail and Information Retrieval

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