Why Blood is Red in colour ?


Red blood cells contain the protein haemoglobin , which gives it it’s red colour .  To be more precise, the haem group of protein molecules – or even more precisely the iron attached to them – it is responsible for the colour .
                                                 

                                                     
                                                            Haemoglobin ‘s task is to bind with the oxygen in the lungs , transport it to the rest of the body and then release it .  To do this , the haem group enters into a loose chemical bond with oxygen , which is easily released in surroundings where oxygen is in short supply .



 Haemoglobin is bright red when full of oxygen . Without oxygen , the molecular structure changes and with it the absorption of light dicates its colour . This is why blood that is deficient in oxygen appears darker .