In a study of the alpine wildflower *Silene acaulis*, ecologist Dr. Elena Rostova investigated the relationship between the plant's root exudates and mycorrhizal fungi. Rostova hypothesized that *S. acaulis* alters the chemical composition of its root exudates to recruit specific nitrogen-fixing fungi only when soil nitrogen levels are depleted. Which choice, if true, would most directly support Rostova's hypothesis?
- When grown in nitrogen-deficient soil, *S. acaulis* plants exuded higher concentrations of specific flavonoids known to attract nitrogen-fixing fungi than did *S. acaulis* plants grown in nitrogen-rich soil.Cevap
- B*S. acaulis* plants grown in soils inoculated with nitrogen-fixing fungi demonstrated greater leaf surface area and overall biomass compared to those grown in sterile soils.
- CDue to changing environmental pressures, alpine soils will likely experience nitrogen depletion, causing *S. acaulis* to rely more heavily on mycorrhizal fungi in the future.
- D*S. acaulis* plants exuded the same composition of organic acids regardless of whether they were grown in nitrogen-deficient or nitrogen-rich soils, though fungal recruitment varied.
Cevap
When grown in nitrogen-deficient soil, *S. acaulis* plants exuded higher concentrations of specific flavonoids known to attract nitrogen-fixing fungi than did *S. acaulis* plants grown in nitrogen-rich soil.
The correct answer provides direct evidence for the hypothesis by demonstrating a clear difference in the chemical composition of root exudates (higher concentrations of specific flavonoids) when the plant is grown in nitrogen-deficient soil compared to nitrogen-rich soil, and specifies that these chemicals are known to attract the target fungi.
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