Hypothesis if plants are grown in soil containing worms then
Because

If plants are grown in soil containing worms, then the plants will grow faster

Explanation:

because worms dig tunnels in the ground.  These tunnels create a path for air which is beneficial for the plant.  Also, worms create nutrient rich fertilizer for the plant

b. the carbon cycle ensures living things have a source of hydrogen

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.