The interdependence of body systems is essential because ?

C. all systems work together to maintain homeostasis. 
an organism is a collection of Organ systems each of which must work in unison for proper function. This is why an infection in one organ often causes complications in another.

Only algae, oak trees, and bermuda grass produce atp by photosynthesis i am almost positive

Because the carnivores keep the herbivore population in check