2. What is it called when certain species have evolved such intimate symbiotic relationships that individuals of elther species cannot survive without one another? facultative
mutualistic
parasitic
obligate​

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.

answer;

a. sheep consumption efficiency would be reduced.

explanation;

-trophic efficiency is a measure of how much energy occurs at one level divided by the energy at the level immediately below it . trophic efficiency incorporates three types of efficiency:

-the proportion of available energy that is consumed (consumption efficiency).   it is the proportion of the available biomass that is ingested by consumers.

-the proportion of ingested food that is assimilated (assimilation efficiency).

-the proportion of assimilated food that goes into new consumer biomass (production efficiency).

-in this case, the grasshoppers would affect sheep by reducing the proportion of the available biomass that is ingested by the sheep.