Quorum sensing Transitional Reasoning Download PDF

Questions

1. 1.

   A culture of bioluminescent marine bacteria emits light only after reaching a high cell density in an enclosed growth medium. In an experiment, researchers removed the bacterial cells from a high-density, glowing culture using a fine filter and introduced this cell-free liquid into an isolated, low-density culture that was not yet luminescent. Shortly after the addition, the low-density bacteria began emitting light without any immediate increase in their cell count. Based on these observations, which conclusion best explains the mechanism underlying this synchronized bacterial response?

   • A) The bacteria activate bioluminescence solely through direct physical contact between their adjacent cell walls.
   • B) The low-density cells rapidly absorb extracellular ATP released by the filtered donor culture to energize light emission.
   • C) The accumulation of a secreted signaling molecule reached a critical concentration threshold that induced coordinated gene expression.
   • D) The filtered liquid depleted vital growth nutrients, prompting the bacteria to emit light as a general starvation survival response.