Why are traits able to vary in the same family

Explanation:

because traits come from generations past. One trait is chosen out of many past traits for every indivudual, but everyone still carries genes to different traits

organisms that are both used in toothpaste as well as cause malaria are protista and monera.

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.