A population is all the individual organisms found in a given habitat, of one species. So you could talk about a population of wolves in the woods. If you want to talk about the wolves and rabbits in the woods, then you’d be referring to a community.
A community is made up of the various populations in a habitat. So the summation of all the living things in a given area is called a community. What then is an ecosystem?
An ecosystem comprises the community of living organisms in a habitat, together with all the non-living components such as water, soil, temperature, etc. called abiotic factors.
As such, the biotic component of the ecosystem consists of the ecological community.
Not all organisms feed the same. Some make their own food and energy, such as photosynthesising plants. These are autotrophs meaning they make their own nutrients, either through light energy or chemical energy.
Some bacteria living in extreme conditions such as deep sea vents rely on chemical reactions to derive energy. Although still autotrophic, these are chemoautotrophic while the photosynthesising organisms are photoautotrophic. Both are…