An organelle found in most eukaryotic cells described as "cellular power plants", because their primary function is to convert organic materials into energy in the form of atp.

The cell organelle that is been described in the question is the MITOCHONDRIA.

Explanation:

Mitochondria is a cell organelle that is found in almost all eukaryotic cells, this is because it performs very crucial functions that make energy available to eukaryotic organisms. The last stage of cellular respiration, which is electron transport chain reaction takes place inside the mitochondria and it leads to the generation of ATP, which is the energy currency of the cells. Mitochondrial is often refers to as the power house of cells because of its ability to carry out biochemical reactions that generate ATP. Without mitochondria, cells will not be able to generate energy.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms