What is the function of a buffer in biological systems?

In biological systems, the function of a buffer is to maintain pH within normal limits, which is crucial for the proper functioning of enzymes and cellular processes. Buffers are typically weak acids or bases that can absorb excess hydrogen ions (H+) or hydroxide ions (OH-) when they are added to a solution. By doing so, they help prevent significant changes in pH, keeping the environment stable and conducive for biochemical reactions.

Maintaining a stable pH is vital for processes such as enzyme activity, nutrient solubility, and overall cellular health. For instance, human blood has a very precise pH range, around 7.35 to 7.45, and the buffering systems in the blood, such as bicarbonate, play a key role in regulating this pH.

Options that suggest a function of buffers only in increasing pH or neutralizing acids do not accurately capture the broader role of buffers, which is to maintain overall pH homeostasis. Similarly, a method of measuring pH changes does not align with the definition of a buffer, which serves to stabilize pH, not measure it. Hence, the correct answer reflects the overall stabilizing role of buffers in biological systems.