Answer:
- the process of breaking down food to get chemical energy
- to get thermal energy from food to keep ur body warm
- to get chemical energy to carry out body functions and daily activities
- carry out gas exchange in the air sacs
- provides carbon dioxide to the leaves to carry out photosynthesis
- keep organisms alive
- for breathing so that humans can expell the carbon dioxide from the body
(cant think of more answers sry but hope this helps :)))