Question

in mammals and birds why is it necessary to separate oxygenated and deoxygenated blood

Answer 1

It is necessary because mammals and birds are warm blooded. Mixing of theses two will decrease the efficency of blood to carry oxygen and our organs won't be able to work properly. Also ,mammals and birds need to maintain their body temperature (warm blooded) . Mixing of deoxygenated and oxygenated blood will increase their body temperature as the level of carbon dioxide will rise in blood. Mammals and birds have high energy requirements. Mixing of deoxygenated and oxygenated blood will decrease their stamina.

Hope it helps u :)

Answer 2

For Mammals and birds it is necessary to separate oxygenated and deoxy genated blood because the require more oxygen and they have high energy needs  they constantly use energy to maintain their body temperature.