A hospital laboratory discovers that a strain of pathogenic bacteria has developed widespread resistance to a standard antibiotic over several years of clinical use. According to the principles of natural selection, how did this antibiotic resistance most likely arise within the bacterial population?
- AIndividual bacteria sensed the chemical stress and actively modified their cell structures during their lifetime to survive the antibiotic.
- Bacteria with pre-existing genetic variations for resistance survived antibiotic exposure and reproduced, passing the trait to subsequent generations.Cevap
- CThe resistance trait spread rapidly through the population solely because dominant alleles automatically increase in frequency regardless of environmental selection.
- DNon-resistant bacterial cells absorbed viral antibodies from patient bloodstreams to intentionally neutralize the antibiotic medication.
Cevap
Bacteria with pre-existing genetic variations for resistance survived antibiotic exposure and reproduced, passing the trait to subsequent generations.
Natural selection operates on populations through differential survival and reproduction. Within the bacterial population, random genetic mutations provide pre-existing variation. When the antibiotic is introduced, it creates a selective pressure that eliminates susceptible bacteria while allowing resistant individuals to survive and reproduce. Over successive generations, the frequency of resistance alleles increases across the population.
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Mechanism of Natural Selection in Microbial Populations
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