Phytoplankton are important to life on earth because they

Plankton are an important source of food for larger animals. Phytoplankton are the first link in the food chain. They are known as primary producers because they produce the first forms of food. Zooplankton and other small animals that graze on the phytoplankton are known as primary consumers.

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answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion

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.