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Soru

Zorluk: OrtaCommand of Evidence: Textual

Ecologist Dr. Elena Rostova and her team investigated the role of common mycorrhizal networks (CMNs)—underground fungal connections between plants—in facilitating resource sharing among Douglas fir (*Pseudotsuga menziesii*) seedlings during acute drought conditions. Rostova hypothesized that older, established parent trees transmit carbon and defensive signals through the CMN to younger seedlings, thereby significantly increasing the seedlings' survival rate compared to seedlings isolated from the network. Which finding from Rostova's study, if true, would most directly support her hypothesis?

  1. A
    Older parent trees connected to the common mycorrhizal network demonstrated greater overall root biomass and took up water from deeper soil horizons than parent trees that were isolated from the network.
  2. B
    Common mycorrhizal networks are the most crucial factor in forest resilience, suggesting that future reforestation efforts should rely exclusively on introducing fungal spores to soil.
  3. Douglas fir seedlings connected to the common mycorrhizal network of an older parent tree showed significantly higher concentrations of parent-derived carbon and defensive proteins, and had a higher survival rate during the drought, than seedlings whose connection to the network had been severed.Cevap
  4. D
    Douglas fir seedlings that were isolated from the network survived the drought at equivalent rates to connected seedlings by absorbing carbon directly from the atmosphere.

Cevap

Douglas fir seedlings connected to the common mycorrhizal network of an older parent tree showed significantly higher concentrations of parent-derived carbon and defensive proteins, and had a higher survival rate during the drought, than seedlings whose connection to the network had been severed.
The finding that connected seedlings had higher parent-derived carbon, defensive proteins, and survival rates directly supports the hypothesis by demonstrating both the transmission of resources from parent trees to seedlings and the resulting survival benefit for those seedlings.

Adım Adım Çözüm

1
Identify the hypothesis in the passage.
The hypothesis is that older parent trees transmit carbon and defensive signals through common mycorrhizal networks (CMNs) to younger seedlings, which significantly increases the seedlings' survival rate during drought compared to isolated seedlings.
Understanding the specific relationship and outcome predicted by the hypothesis is necessary to evaluate which finding supports it.
2
Evaluate each option to see if it provides evidence of both resource transmission and increased seedling survival.
The correct option provides evidence of both: connected seedlings had higher parent-derived carbon and defensive proteins (evidence of transmission) and a higher survival rate (evidence of increased survival).
A supporting finding must align with all components of the hypothesis.
3
Eliminate options that support unrelated claims, make speculative generalizations, or contradict the hypothesis.
The options concerning parent tree root biomass (unrelated), forest resilience speculation (speculative), and equivalent survival rates of isolated seedlings (contradictory) are eliminated.
This ensures the selected option is the only one that directly and logically supports the researcher's specific claim.

Anahtar Kavram

Identifying textual evidence that directly supports a specific scientific hypothesis.
Tahmini Süre:1m 30s
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Konular

Command of Evidence: Textual

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