10. The classifying of organisms from kingdoms to species is
A. Taxonomy
B. Kingdoms key
C. Dichotomous key

We can use solar powered cars or ride bikes instead of cars that burn fossil fuels

only b 

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.