Question

Explain with reasons.

Human blood is red coloured.

Answer 1

Blood is red because it is composed of red cells known as red blood cells. Hemoglobin is a protein found within red blood cells. Each hemoglobin protein is composed of subunits known as hemes, which are responsible for the red colour of blood. Hemes, in particular, can bind iron molecules, and these iron molecules bind oxygen. Because of the interaction between iron and oxygen, blood cells are red. When iron is oxygenated, it turns red, and blood turns red as a result.