A Level Biology Practice Exam

What is the role of haemoglobin in the human body?

1. Transporting nutrients

2. Carrying oxygen in red blood cells

3. Defending against pathogens

4. Regulating body temperature

The correct answer is: Carrying oxygen in red blood cells

Haemoglobin plays a crucial role in the human body by carrying oxygen in red blood cells. This protein, found within red blood cells, binds to oxygen molecules in the lungs as blood is exposed to the oxygen-rich environment. Once bound, haemoglobin transports these oxygen molecules through the bloodstream to tissues and organs where they are needed for cellular respiration and other metabolic processes. The efficiency of haemoglobin in this role is enhanced by its ability to release oxygen in areas where it is most needed, such as in tissues with high carbon dioxide concentrations or low pH, which indicates a higher metabolic activity. This property allows for effective oxygen delivery that supports overall body functionality. Additionally, haemoglobin also plays a minor role in transporting carbon dioxide back to the lungs for exhalation, but its primary function is clearly centered on oxygen transport, highlighting the significance of this aspect in maintaining homeostasis and supporting life processes.