Break down dead organisms to nutrients. Food sources for humans. Some cheeses get their flavor from fungi. Yeast is used to leaven bread and produce ethyl alcohol for making beer and wine. Plantae - make their own nutrients converting solar energy into chemical energy in the bonds of sugar molecules.
Plants are a major food source for many other organisms.
Most of our plant foods come from Angiosperms, the flowering plants. Animalia - ingest and internally digest their food. We interact with this group in many intimate ways, from food to pets. They cell wall structure is different than that of typical bacteria.