Which of the following scenarios best describes quorum sensing in microorganisms?

• A. Bacteria release signaling molecules to coordinate gene expression once a critical population density is reached.
• B. Viruses infect host cells and use the host machinery to replicate their genomes.
• C. Fungi produce spores to survive unfavorable environmental conditions.
• D. Protozoa move toward a food source using flagella.

Answer: (A)

Verified step by step guidance

1. Understand the concept of quorum sensing: it is a communication mechanism used by microorganisms, especially bacteria, to detect and respond to the density of their population through signaling molecules.
2. Identify the key feature of quorum sensing, which is the release and detection of signaling molecules (autoinducers) that accumulate as the population grows.
3. Recognize that once a threshold concentration of these signaling molecules is reached, bacteria collectively change their gene expression to coordinate behaviors such as biofilm formation, virulence, or bioluminescence.
4. Compare the given scenarios to this definition: only the scenario where bacteria release signaling molecules to coordinate gene expression at a critical population density matches quorum sensing.
5. Exclude other options as they describe different biological processes unrelated to quorum sensing, such as viral replication, fungal spore production, or protozoan movement.