Question

Is human blood purple?

Answer 1

Blood is a type of special connective tissue. Its colour depends on the oxygen-binding protein presents in the blood. Different organisms have different protein pigment depending upon the habitat they live.

Complete answer:
Human blood is made up of special connective tissues and it consists of a fluid matrix, plasma and blood corpuscles. Human blood consists of haemoglobin protein pigment which is dark red due presence of iron in its centre and when this haemoglobin gets bound with oxygen it becomes oxygenated and gets turned into a bright red colour. So, human blood is red and the colour is not purple.

Additional information:
Purple blood is present in some marine forms due to the presence of oxygen-binding protein, hemerythrin. In some organisms, it turns colour similar to haemocyanin when getting oxygenated. This type of pigment is present in peanut worm and sea- squirt species.
The pigment chlorocruorin is similar to haemoglobin in chemical composition, when it is present in concentrated form it is red but in the diluted form, it is green in colour. This type of pigment is present in polychaetes, which is a type of marine worm.
The polychaetes and peanut worm have translucent skin by which their blood colour becomes visible from the outside surface.

Note:
The four major blood pigments are haemoglobin, haemocyanin, erythrocruorin or chlorocruorin and hemerythrin. All this pigment helps in the binding of oxygen which makes oxygenated blood and it gets transported to all body parts and then to cells. The oxygen transportation via blood pigment helps in the respiration process mainly.