Why is primase required for replication?

Primase is a DNA-dependent RNA polymerase. Primase synthesizes the short RNA molecules, or primers, that provide a 3'–OH to which DNA polymerase can attach deoxyribonucleotides in replication initiation. The DNA polymerases require a 3'–OH to which they add nucleotides, and therefore they cannot initiate replication.

maritime tropical may be your answer.

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.