OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is formed when haemoglobin bonds with oxygen in the lungs?

1. Carbon monoxide

2. Oxyhemoglobin

3. Deoxyhemoglobin

4. Blood plasma

The correct answer is: Oxyhemoglobin

When haemoglobin bonds with oxygen in the lungs, the resulting compound is known as oxyhemoglobin. This process is crucial for transporting oxygen from the lungs to the body's tissues. Haemoglobin, a protein found in red blood cells, has the ability to bind with oxygen molecules, and when it does so, it undergoes a structural change that forms oxyhemoglobin. This is vital for maintaining proper oxygen levels in the bloodstream and ensuring that all cells receive the oxygen they need for cellular respiration. The formation of oxyhemoglobin allows for efficient oxygen transport, as each molecule of haemoglobin can carry up to four oxygen molecules, significantly increasing the amount of oxygen that can be delivered throughout the body. In contrast, carbon monoxide is a harmful gas that can bind to hemoglobin, but it does not form oxyhemoglobin. Deoxyhemoglobin refers to haemoglobin that has released its oxygen and is therefore not bound to oxygen. Blood plasma is the liquid component of blood in which cells and other substances are suspended, but it does not directly relate to the process of oxygen binding with haemoglobin. Thus, the formation of oxyhemoglobin is a key aspect of oxygen transport in the bloodstream.