If there are more no. of cells than it is a multicellular organism and if there is only one cell it is unicellular organism. in every organismthe cell is the basic unit of the life which contains specialized cell organelles which perform all the functions in it. in complex eucaryotic multicellular organisms these organelles are membrane bound so that it can takeup efficient chemical reaction required for the cells as well as the body. while in unicellular organism the neucleus carries the metabolic pathways and its simpler organism the diffusion of the food in unicellular organism is more easier and simpler than in multicellular organisms . so the functioning in both of them varies.
#PLZ MARK IT AS BRAINLIEST#