Advanced Placement (AP) Chemistry Practice Exam

How do buffers contribute to homeostasis in living organisms?

1. They increase the rate of digestion.

2. They regulate temperature extremes.

3. They help maintain stable pH levels in bodily fluids.

4. They enhance oxygen transportation in blood.

The correct answer is: They help maintain stable pH levels in bodily fluids.

Buffers play a crucial role in maintaining homeostasis by helping to manage the pH levels of bodily fluids. In living organisms, many biochemical processes are highly sensitive to changes in pH. For example, enzymes, which are vital for metabolic reactions, only function optimally within specific pH ranges. When there are fluctuations in pH levels, buffers can neutralize excess acids or bases, thus stabilizing the pH environment necessary for these biological processes to occur effectively. The importance of stable pH levels cannot be overstated. If the pH of blood or cellular fluids deviates significantly from its normal range (approximately 7.4 for blood), it can lead to serious health consequences, including metabolic disturbances or dysfunction of vital systems. While factors like digestion, temperature regulation, and oxygen transportation are all critical to overall health, they don't directly relate to the specific function that buffers have in maintaining pH stability within the body. Buffers are essentially the body's first line of defense against pH changes, ensuring that the internal environment remains conducive to life.