Problem 2 - The mass of Earth is 6.0x1024 kg. The mass of a hydrogen atom is 1.6x10-27 kg. If the entire mass of the shell were evenly spread out in a sphere with the
shell's radius, how many hydrogen atoms would you expect to find in a cubic meter of
this shell to the nearest 10,000 atoms?

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.