What role does hemoglobin play in the body?

Hemoglobin plays a crucial role in the body primarily by transporting oxygen from the lungs to the tissues and carrying carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation. This protein is found in red blood cells and is essential for maintaining adequate oxygen levels in the bloodstream, which is vital for cellular respiration and energy production.

The structure of hemoglobin allows it to bind effectively with oxygen in areas of high concentration (like the lungs) and release it in areas where it is needed (like active tissues). Additionally, hemoglobin helps in the transport of carbon dioxide; it can bind to carbon dioxide formed in the tissues and carry it back to the lungs, aiding in the respiratory process. This dual role is critical for maintaining homeostasis within the body and supports overall metabolic processes.

Other options, such as transporting hormones or regulating body temperature, do not accurately describe hemoglobin's specific functions. While glycogen storage is important for energy, it is unrelated to the role of hemoglobin. Thus, the essential task of hemoglobin in facilitating oxygen and carbon dioxide transport is what solidifies answer B as the correct choice.