Answer:
.Red blood cells (RBCs) appear red due to the presence of hemoglobin, a protein molecule that carries oxygen from the lungs to the body's tissues and carbon dioxide back to the lungs for exhalation. Hemoglobin contains iron, which binds to oxygen, giving RBCs their characteristic red color when oxygenated.
The color of hemoglobin-bound oxygen is red because of the specific way in which light interacts with the iron atom within the hemoglobin molecule. When oxygen binds to the iron, it changes the electronic structure of the iron atom, causing it to absorb certain wavelengths of light and reflect others. The wavelengths of light that are reflected give rise to the red color we perceive.
Other colors are not present because hemoglobin does not interact with light in the same way when it is not bound to oxygen. Deoxygenated hemoglobin has a slightly different electronic structure, which affects the way it interacts with light, resulting in a darker red or purplish color.
So, the specific molecular structure of hemoglobin and its interaction with light are what give red blood cells their distinctive red color, and this color is not seen in the absence of oxygen binding to hemoglobin.
