MCQ Detailed View

Hemoglobin is a specialized protein molecule in red blood cells (RBCs) that plays a crucial role in transporting oxygen from the lungs to body tissues and carrying carbon dioxide back to the lungs for exhalation. The main constituent of hemoglobin is iron (Fe), which is an essential element for its function.Each hemoglobin molecule is made up of four protein chains (globin) and four heme groups. At the center of each heme group is an iron atom that has the unique ability to bind with oxygen molecules (O₂). When blood passes through the lungs, iron in hemoglobin captures oxygen, forming oxyhemoglobin, which is then delivered to tissues throughout the body. This process is vital for cellular respiration, which generates energy for all body activities.

Without sufficient iron, the body cannot produce enough functional hemoglobin, leading to a condition called iron-deficiency anemia. Symptoms of anemia include fatigue, weakness, pale skin, and difficulty concentrating due to reduced oxygen supply to organs.

Explanation of other options:

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  Chlorine: Not a component of hemoglobin; mainly found in the body as part of salts for fluid balance.

  
  


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  Calcium: Important for bones, teeth, and nerve function, but not a constituent of hemoglobin.

  
  


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  None of these: Incorrect because iron is the correct answer.

  
  

The presence of iron in hemoglobin also gives red blood cells their characteristic red color. Adequate dietary intake of iron from sources such as red meat, leafy greens, beans, and fortified cereals is crucial for healthy blood and proper oxygen transport.

In conclusion, iron is the main constituent of hemoglobin, making option B (Iron) the correct answer for this biology MCQ.