Quorum sensing Transitional Reasoning Practice

Questions

1. 1.

   A researcher investigates a mutant strain of bacteria that lacks the gene encoding autoinducer synthase and observes that even at high population densities, the culture fails to form a protective biofilm. However, when cell-free liquid medium harvested from a dense, biofilm-producing wild-type culture is added to these mutant cells, biofilm-related genes are promptly activated. Based on this experimental outcome, which conclusion is best supported regarding the regulation of this collective behavior?

   • A) Direct physical contact between bacterial cell surfaces is required to initiate coordinated biofilm development.
   • B) Biofilm gene activation depends on the extracellular concentration of a diffusible chemical signal rather than physical contact between cells.
   • C) The mutant strain carries defective receptor proteins that permanently block intracellular signal transduction pathways.
   • D) High bacterial population density inherently suppresses the transcription of collective survival genes in wild-type strains.

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