Why is gene regulation necessary in the development of multicellular organisms? give a specific example to support your answer.

Is very necessary in the development of multiceular organisms. This is so because the complexity of animals and plants depends on a remarkable feature of the genetic control system. Cells have a memory: the genes a cell expresses and the way it behaves depend on the cell's past as well as its present environment. Hope this info has given you the answer you need 

Interacting group of various species in a common location. for example, a forest of trees and undergrowth plants, inhabited by animals and rooted in soil containing bacteria and fungi, constitutes a biological community.