WHY IS BLOOD RED??

red blood cells contains the protein heamoglobin,which gives it its red colour.to be more precise,the haem group of proteins molecules-or even more the iron attached to them is responsible for the colour.heamoglobin's task is to bind with oxygen in the lungs,transport it to the rest of the body and then release it.to do this,the heam group enters into a loose chemical bond wit oxygen,which is easily released in surroundings where oxygen is in short supply.heamoglobin is bright red when full of oxygen.without oxygen,the molecular structure changes and with it the absorption of light tat dictates its colour.this is why blood tat is deficient in oxygen appears darker