Adherent cultures are characterized by what behavior?

• A. Cells that float freely
• B. Cultures in which cells adhere to a surface and stop growing
• C. Cultures that grow only in suspension
• D. Cells that adhere to a surface and stop growing

Answer: (D)

Adherent cultures rely on cells attaching to a solid surface to grow. They spread out on the dish and proliferate as a monolayer, but when the surface becomes fully occupied, growth stops because of contact inhibition. So the best description is that these cells adhere to a surface and stop growing. This contrasts with suspension cultures, where cells float and do not require attachment. The phrase about growing only in suspension would describe the opposite type of culture, and floating cells clearly indicate non-adherent behavior.