If cells converting oxygen and carbohydrates into carbon dioxide, water, and energy is a requirement for life, then what is cells converting oxygen and carbohydrates into carbon dioxide, water, and energy?

Answer choices:
- not necessary for life
 - requirement for life
 - Most plants
 - one celled organisms
 - digestion
 - they body they live in
 - h2o
 - circulatory systems

 

  requirement for life        