Adifference between miocene apes and modern apes is the

A difference between miocene apes and modern apes is the degree of mobility of their wrists.Miocene apes have limited wrist mobility while modern apes has highly mobile wrist. Other differences include: degree of extension of elbows; miocene apes can not fully extend their elbow while modern apes can.  

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.