Describe a grassland ecosystem briefly.​

A grassland is a biome, an area of land that mostly has grasses. There are wild grasses, and there may be some trees. Several parts of the world have grasslands. Grasslands are found in Africa, North America, Central Asia, South America, and near the coasts of Australia.

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.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.