Question

Which one of the following is an example of a buffer system in blood ?
(A) Haemoglobin and oxyhaemoglobin
(B) Oxygen and carbon dioxide
(C) Albumin and globulin
(D) Sodium bicarbonate and carbonic acid

Answer 1

Hint: Human blood contains a buffer of carbonic acid ($H_{2}CO_{3}$) and bicarbonate anion ($HCO_{3-}$) in order to maintain this blood pH between 7.35 and 7.45 , and also the value higher than 7.8 or lower than 6.8 can leads to death. In this buffer, hydronium and bicarbonate anion are in equilibrium with carbonic acid.

Complete Answer:
- The body’s chemical buffer consists of three individual buffers, they are: carbonic acid, the phosphate buffer, and the buffering of plasma protein.
- Carbonic acid is a weak acid which is in equilibrium with bicarbonate in solution. When significant amounts of carbonic acid and bicarbonate are present, a buffer is formed.
- Metabolism produces more acids than bases and which is consistent with the body’s needs. The blood, with high base concentration is able to neutralize the metabolic acids.
- While in the blood, bicarbonate ions serve to neutralize and are introduced into the blood through other metabolic processes.
- In the body, there exists another equilibrium between hydronium and oxygen which involves the binding ability of haemoglobin. An increase in hydronium causes the equilibrium to shift towards the oxygen and releases oxygen from haemoglobin molecules into the surrounding cells.

Thus, the option (D) is correct.

Note: Buffers are used often in biological research to maintain the pH of a specific process. This can be useful when the bacteria are culturing, and also their metabolic waste can affect the pH of their medium, consequently killing the sample. Many buffers have separate functions.