Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.
B. The levels of classification increased. Previously there were only 2 domains of life, Bacteria and Eukarya, but an additional domain and Kingdom were added when the distinction of Archaea was observed.
Earth's mantle plays an important role in the evolution of the crust and provides the thermal and mechanical driving forces for plate tectonics. Heat liberated by the core is transferred into the mantle where most of it (> 90%) is convected through the mantle to the base of the lithosphere.
