What is the role of an enzyme in a reaction with the reaction ? would the reaction happen without an enzyme?

Enzymes are not used up in a chemical reaction. Usually, the enzyme will “reset” and be ready to use in another reaction. This is due to the fact that enzymes are proteins, and their shape is what they use in a chemical reaction.

Explanation:

Enzymes serve a similar purpose for chemical reactions in an organism's body, which is to lower the amount of "activation energy" needed for a particular chemical reaction to occur. Without enzymes, many chemical reactions would occur at a much slower rate because the amount of activation energy required would be far greater.

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.

the answer is sex-linked recessive.