The significance of pH levels in biology is profound, as they influence enzyme activity, metabolic processes, and overall cellular function. Variations in pH can affect the ionization of molecules, thereby impacting reaction rates and the structural stability of proteins. Different biological systems have optimal pH ranges; for instance, human blood maintains a pH around 7.4. Any deviations from this range can lead to acidosis or alkalosis, both of which can be harmful to physiological processes and overall health.