Define Homeothermy and Poikilothermy.

(N/A) $1$. Homeothermy (Endothermy): It is the ability of an organism to maintain a constant internal body temperature regardless of the external environmental temperature. Examples include mammals and birds.
$2$. Poikilothermy (Ectothermy): It is the condition where an organism's internal body temperature fluctuates in accordance with the changes in the external environmental temperature. Examples include most reptiles,amphibians,and fish.