A Level Biology Practice Exam

Which of the following statements is true about the formation of oxyhaemoglobin?

1. It occurs when carbon dioxide binds to haemoglobin

2. It occurs in the body tissues when oxygen is released

3. It is formed when haemoglobin takes up oxygen molecules

4. It cannot occur at high altitudes where oxygen levels are low

The correct answer is: It is formed when haemoglobin takes up oxygen molecules

The statement about the formation of oxyhaemoglobin being true is rooted in the fundamental mechanism of oxygen transport in the blood. Oxyhaemoglobin is formed when haemoglobin, a protein found in red blood cells, binds to oxygen molecules. This process occurs in areas of high oxygen concentration, such as the lungs. When oxygen enters the bloodstream, it diffuses into the red blood cells and associates with haemoglobin, resulting in the formation of oxyhaemoglobin. This compound is crucial for the efficient transport of oxygen throughout the body to tissues and organs that need it for cellular respiration. The other statements do not accurately describe the process or conditions surrounding oxyhaemoglobin formation. While carbon dioxide does interact with haemoglobin, it does not lead to the creation of oxyhaemoglobin. When hemoglobin releases oxygen, it does so primarily in tissues where oxygen levels are lower, but this is not the same as forming oxyhaemoglobin. Finally, the formation of oxyhaemoglobin can occur even at high altitudes, although the amount of oxygen available in the air is reduced, and hence the total oxygen saturation may be lower than at sea level. Thus, the understanding of how oxyhaemoglobin forms is critical to grasping how oxygen