Confluence in cell culture refers to what?

• A. The percentage of the surface covered by cells
• B. The volume of medium
• C. The color of the culture
• D. The number of counters in the incubator

Answer: (A)

Confluence measures the percentage of the culture surface that is covered by adherent cells. As cells grow and spread, they occupy more of the dish or flask surface. This helps you know when to passage or harvest, since growth behavior changes as surface coverage increases toward full occupancy. The other options—volume of medium, color of the culture, or the number of counters in the incubator—do not describe how much surface is occupied by cells.