5. Why do thorns and spines exist? * O To stop animals from eating plants
To stop insects from pollinating
To stop people from looking at plants
O To help plants stay standing upright and give them their shape

to stop animals from eating plants

Explanation:

the thorns and spines help protect the plant for example if we touch the plant it hurts same goes with animals

A. To stop animals from eating plants

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.