Explain why the body does not need to put in any more energy once the substrate has
reached its transition state

"a.) well–developed vascular system."

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.