A conjugate base is the species that remains after an acid has donated a proton (H+). It is the counterpart to the acid in a Brรธnsted-Lowry acid-base reaction, playing a critical role in buffer systems by helping to maintain pH levels and cellular homeostasis. Understanding conjugate bases is essential for comprehending how acids and bases interact in biological systems, particularly in regulating the acidity of bodily fluids and maintaining a stable environment for cellular functions.