Question

Difficulty: MediumSpecific Detail Inferences

Read the following passage carefully.

In recent decades, ecologists have increasingly focused on the complex subterranean networks formed by mycorrhizal fungi, which connect the root systems of multiple plants. These networks facilitate the transfer of resources such as carbon, nitrogen, and water between trees. Initial hypotheses posited that these fungal connections functioned primarily as mutually beneficial trade routes between the fungi—which require photosynthetic carbon—and trees, which require soil nutrients. However, recent studies observing resource transfer between disparate tree species have prompted a reevaluation of this model.

One compelling observation is that "hub trees"—the oldest and most heavily networked trees in a forest—often disproportionately allocate carbon to establishing seedlings. While this appears to be a clear instance of kin selection when the seedlings are genetically related to the hub tree, researchers have documented significant carbon transfer to seedlings of entirely different species. This interspecific resource sharing presents a challenge to classical neo-Darwinian models of competition, which would predict that a tree should maximize its own fitness or that of its close relatives rather than subsidizing potential competitors for canopy space.

To reconcile these observations, some evolutionary biologists suggest that the mycorrhizal fungi themselves are the primary drivers of these resource transfers. From the fungus's perspective, maintaining a diverse array of host plants provides a buffer against species-specific pathogens or environmental changes that might decimate a monoculture. Consequently, the fungi may actively distribute carbon drawn from successful, established trees to struggling seedlings of various species, thereby ensuring a resilient, mixed-species forest that offers a more stable long-term habitat for the fungal network.

Evaluate the following statement:

Based on the passage, it can be inferred that a mycorrhizal fungal network spanning a forest composed entirely of a single tree species is more susceptible to catastrophic habitat loss from pathogens than a network connecting multiple distinct tree species.

Answer: Answer

Answer

The statement is true.
The statement correctly synthesizes two linked details from the final paragraph: that diverse host plants provide a buffer against species-specific pathogens, and that such pathogens might decimate a monoculture. Since the interconnected trees constitute the long-term habitat for the fungal network, it logically follows that a network relying entirely on a single tree species (a monoculture) is far more vulnerable to losing its habitat to specific pathogens than a network connecting multiple, diverse species.

Step-by-Step Solution

1
Analyze the core claim of the provided statement.
The statement claims that a fungal network in a single-species forest (a monoculture) is more vulnerable to pathogen-induced habitat loss than a network in a diverse, mixed-species forest.
Understanding the exact parameters of the required inference directs where to look for supporting evidence in the text.
2
Locate the specific details in the passage discussing pathogens, monocultures, and network stability.
The final paragraph explains that maintaining a diverse array of host plants provides a "buffer against species-specific pathogens" that might "decimate a monoculture," which in turn ensures a "more stable long-term habitat for the fungal network."
Specific detail inferences must be directly supported by textual evidence.
3
Evaluate whether the passage's details logically necessitate the statement's conclusion.
Because diverse hosts act as a protective buffer and provide a stable habitat, the absence of this diversity (a single-species forest) logically results in greater susceptibility to the pathogens mentioned.
This confirms that the inference is a valid deduction based strictly on the provided text.

Key Concept

Specific Detail Inferences in Reading Comprehension
Estimated Time:1m 30s
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