Which substance acts as a buffer in many organisms?

Bicarbonate acts as buffer in many organisms.

Explanation:

Buffer may be defined as the chemical that resist the change of pH by the addition of a base or acid. The buffer is made up by the mixture of weak acid and its conjugate base.

The blood has pH 7.4 and bicarbonate ions acts as buffer. The bicarbonate ions absorb H + ions in case of low pH and releases carbonate ions. Here, the bicarbonate ions maintain the pH of the body and maintains homeostasis as well.

Thus, the answer is bicarbonate ions.

Answer;

-Carbon dioxide/bicarbonate

Explanation;

A buffer is a substance that resists changes in pH. Buffers act by releasing hydrogen ions when a base is added and absorbing hydrogen ions when acid is added, with the overall effect of keeping [H+] relatively constant.

For example, the key buffer in human blood is an acid-base pair consisting of carbonic acid (acid) and bicarbonate (base). These two substances interact in a pair of reversible reactions. First, carbon dioxide (CO2) and H2O join to form carbonic acid (H2CO3), which in a second reaction dissociates to yield bicarbonate ion (HCO3-) and H+.

If some acid or other substance adds H + to the blood, the HCO3 - acts as a base and removes the excess H + by forming H2CO3. Similarly, if a basic substance removes H + from the blood, H2CO3 dissociates, releasing more H + into the blood. The forward and reverse reactions that interconvert H2CO3 and HCO3 - thus stabilize the blood's pH.