Millimeters are the answer here friend. hope you have a bugunga day!
(pronounced bu-gun-ga)
they need energy because growth is not the only life process that requires energy.Apart from growth, when organism reaches adulthood they need energy to aid in other processes such as locomotion,reproduction. More also, important functions such as cell replacement requires energy.
In the domain system, the domain Eukarya includes organisms from more than one kingdom.