Question

Reduction in pH in blood will
(a)Reduce the rate of heartbeat
(b)Reduce the blood supply to the brain
(c)Decrease the affinity of hemoglobin with oxygen
(d)Release bicarbonate ions by the liver

Answer 1

Hint: The structure of the hemoglobin molecule is affected by the slight difference in pH and this difference itself is responsible for bringing about a change in the hemoglobin's structure that is crucial for its primary function in our body.

Complete answer:
oxygen. To understand this, we need to understand the effect of pH on the transport mechanisms occurring in the blood first. The pH balance in our blood is also referred to as its acid-base balance and in our body, there is an optimum level for acids and bases in our blood at which our body can perform its functions in a normal way. With the help of organs like lungs and kidneys, our body maintains this optimum pH. There are many biochemical processes occurring in our bodies that are sensitive to the pH. Majorly, the carbon dioxide concentration determines the pH of our blood. When it reacts with water in the presence of enzyme carbonic anhydrase, carbonic acid is formed. This carbonic acid loses a hydrogen ion to become the carbonate ion as shown in the reaction below –
${ CO }_{ 2 }+{ H }_{ 2 }O\longleftrightarrow { H }_{ 2 }{ CO }_{ 3 }\longleftrightarrow { H }^{ + }+{ { HCO }_{ 3 }^{ - } }$
In the effect of this bicarbonate ion, the pH of the blood decreases, and this decrease in pH causes such change in the structure of hemoglobin that promotes the dissociation of oxygen from hemoglobin. In this way, the surrounding tissues obtain the necessary amount of oxygen to meet their demands and perform functions. Thus, it is now known to us that if the pH of the blood decreases, the affinity of hemoglobin towards the oxygen is also decreased and its dissociation occurs.
So, the correct answer is 'decrease the affinity of hemoglobin with oxygen'.

Note: As the value of pH increases in the blood, loss of the hydrogen ions from specific amino acids occurs at the key sites in the structure of hemoglobin. Due to this, a change in the structure of hemoglobin occurs that increases its ability to bind oxygen. But in the opposite case when pH decreases, hemoglobin picks up hydrogen ions and its affinity for oxygen is reduced.