The average heart beats about 100,000 times a day. true or false?

True since an average heart beats 72 times per minute.so in a day it comes around 72*60*24 which is approximately 100000

Yes, it is true that the average heart beats about 100,000 times per day. it is about 70 beats of the hear per minute. 

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.