If proteins could fold only into rigid, inflexible structures, how might this affect the cell's ability to regulate their function?

A protein activity is regulated by controlling when or where it is folded into its active form. Many proteins are in a flexible, inactive form until bound to molecules or ions. If proteins has only a single, inflexible folded conformation, this type  of control could not occur.

lets get this bread mom

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.