Question

_____ element is common in haemoglobin and myoglobin.
A. Fe
B. Cu
C. Mn
D. Mg

Answer 1

Hint: Iron is very essential for blood production. It helps in the growth and development of our body. Sometimes, the body requires iron to make some hormones. The main function of iron in our body is to carry oxygen from the lungs to all parts of our body.

Complete answer:
About 70% of total body iron is present in both haemoglobin and myoglobin. Haemoglobin is present in RBC. It helps in transferring oxygen in our body from the lungs to the tissues. Myoglobin present in muscles cells accepts, stores, transports and releases oxygen, Hence, ‘option A’ is correct.
The human body contains approximately 2mg of copper per kilogram of body mass. It is found throughout our body but found more concentrated in organs with high metabolic activity such as the liver, kidneys, heart and brain. It acts as essential cofactors in some enzymes. Hence, ‘option B’ is incorrect.
The human body contains about 10 - 20 mg of manganese, out of which 25% - 40% is present in bone. The liver, pancreas, kidneys and brain also contain manganese. It acts as cofactors for many enzymes. It plays an important role in blood clotting and haemostasis in conjugation with vitamin K. Hence, ‘option C’ is incorrect.
The human body contains around 25 g magnesium, out of which 50% - 60% is present in the bones and in soft tissues. Less than 1% of total magnesium is present in blood serum. It acts as cofactors for many enzymes that regulate protein synthesis, blood glucose control, blood pressure regulation and muscle and nerve function. It is useful for the production of energy, oxidative phosphorylation and glycolysis. It helps in the development of bone and is required for the synthesis of DNA and RNA. Hence, ‘option D’ is incorrect.

Hence, the correct answer is option (A).

Note: Haemoglobin has a strong affinity towards oxygen and it binds with oxygen to form oxyhaemoglobin. Around 25% of carbon dioxide in our body binds with haemoglobin to form carbaminohemoglobin. Haemoglobin has a stronger affinity towards carbon monoxide, even more than oxygen. It binds with carbon monoxide to form a stable compound known as carboxyhemoglobin. It forms carbon monoxide poisoning and leads to oxygen deficiency in the body.