Which processes lead to most genetic variation in sexually reproducing organisms? select all that apply. select all that apply. random fertilization independent orientation of chromosomes in meiosis cytokinesis crossing over?

Crossing over, independent orientations (assortment) of chromosomes, random fertilization contribute the process of genetic variation. Crossing over leads to exchange of genetic information in between the sister chromatids. 
The process of independent assortment, during metaphase 1, is responsible for the unique arrangement of the chromosomes, and have 2n possibilities. 
Random fertilization is the cause of the selection of a particular sperm that fuses with the egg and leads to the formation of the embryo, and a typical genetic characteristic is shared between the two. 

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.