Mammals and birds are warm blood organism . They need more energy to maintain constant temperature hence the oxygenated blood and beoxygenated blood necessary to separate for high efficiency (37.c)
Answer:\tIn birds and mammals have a double circulation system where both the oxygenated and deoxygenated blood maintains separate.\tWarm-blooded animals such as birds and mammals maintain constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment.\tHence, these animals require more oxygen\xa0(O2)\xa0for more cellular respiration so that they can produce more energy to maintain their body temperature.\tIt is necessary for them to separate oxygenated and de-oxygenated blood so that their circulatory system is more efficient and can maintain their constant body temperature.\tIt is also better if the oxygenated blood stays separate, as its combination with deoxygenated blood will impure the entire blood.

So that they may survive as deoxygenated blood harms cells of our body

Separation of pure and impure blood is necessary to keep oxygenated and deoxygenated blood away from mixing warm blooded animal such as words and numbers maintain a constant body temperature why cooling themselves when they are in a hotel environment and why warming their bodies when they are in angular environment this animals require more inform more cellular respiration so that they can produce more energy to maintain their body temperature such separation helps in a highly efficient supply of oxygen to the body

Because maintain the body temperature
To maintain the body temperature
Because such separation allows sufficient supply of energy in mammals and birds which constantly use this energy to maintain their body temperature

Thanks
Because deoxygenated blood do not contain oxygen in it that don\’t require by our body and oxygenated blood have rich amount of oxygen if our body don\’t separate them we don\’t get rich amount of oxygen also our circulatory system don\’t work properly