Step-by-step explanation:
The following functions:
1. Capture of energy, chemical elements/substances and information from environment following by transformation into biomass and introduction into ecosystem. In simple words is transformation from abiotic to biotic.
2. Flow of biomass through ecosystem, from one trophic level to another, following different food chain paths. We have there also recycling of disposed organic mass and generating biomass, and reintroducing back into ecosystem
3. Controlling other species, keeping constant the numeric effective of populations of different species in the ecosystem. We have there specialised consumers or predators, non-specialised consumers or predators, specialised parasites and microbes, non-specialised parasites and microbes. Sometimes only food resources is the factor that can stop the species from overpopulating.
4. Decomposing and returning of chemical elements back into environment. So they go back to function 1. So, we have some sort of cycle there. I would say many different cycles.