What make blood to be red?

Question: What make blood to be red?
- Keywords:
  blood,
  red
Asked by Magary to Marta on 11 Jul 2017.
- Marta Maia answered on 11 Jul 2017:
  
  Each hemoglobin protein is made up subunits called hemes, which are what give blood its red color. More specifically, the hemes can bind iron molecules, and these iron molecules bind oxygen. The blood cells are red because of the interaction between iron and oxygen.