$(a)$ How many chambers are present in the heart of $(i)$ fish $(ii)$ amphibians? $(b)$ Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

(N/A) $(i)$ Fish heart has $2$ chambers (one atrium and one ventricle).
$(ii)$ Amphibian heart has $3$ chambers (two atria and one ventricle).
$(b)$ Mammals and birds are warm-blooded animals that maintain a constant body temperature. This process requires a significant amount of energy. Separating oxygenated and deoxygenated blood ensures a highly efficient supply of oxygen to the body tissues,which is essential for meeting these high energy demands.