During tubular secretion, fluid moves where:.

Renal tubular lumen

Explanation:

Tubular secretion is the process where fluid are moved are transfer from the peritubular capillaries to the renal tubular lumen of the kidney by the process of active transport and diffusion. It is the opposite of reabsorption and few substances are secreted in the nephron. Urine is left at reabsorption and secretion has taken place in the nephron.

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.