An agricultural research team investigated an outbreak of fungal root rot in crop fields following the application of a microbial bio-fertilizer. The team hypothesized a specific causal sequence: microbes in the fertilizer produce high concentrations of organic acids, these organic acids degrade root cell membranes, and the damaged membranes subsequently allow opportunistic fungal pathogens to infect the root system.
Which of the following findings, if true, would support the team's proposed causal sequence? Select all that apply.
- Root membrane degradation occurred consistently prior to fungal penetration, and synthetic exposure to organic acids alone produced identical membrane damage in pathogen-free environments.Cevap
- Application of broad-spectrum fungicides successfully eliminated fungal spores but failed to reduce the severity of root membrane degradation in fields treated with the bio-fertilizer.Cevap
- CFungal pathogens, once established inside root tissues, secrete biochemical signals that stimulate soil microbes to increase organic acid production.
- DPlant roots undergoing fungal decay release nutrient exudates that accelerate the growth rate of bio-fertilizer microbes in the surrounding soil.
- ECrop fields utilizing conventional chemical nitrogen fertilizers achieved higher overall harvest yields than fields utilizing microbial bio-fertilizers.
Cevap
The statements confirming that membrane degradation precedes fungal entry (and is inducible by organic acids alone) and that fungicide treatment fails to prevent membrane degradation both support the proposed causal sequence.
The hypothesis posits a sequential causal chain: bio-fertilizer microbes produce organic acid, organic acid damages root membranes, and damaged membranes permit fungal infection. The statement establishing that organic acid alone induces membrane degradation prior to fungal presence confirms the mechanism and sequence. The statement showing that eliminating fungi leaves membrane damage intact confirms that membrane damage is an independent precursor, not a symptom of fungal infection.
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Causal Order and Mechanism Validation in Logical Arguments
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