Today we discussed things such as biomes, ecosystem, and parasites. A biome is a biogeographical unit consisting of of a biological community that has formed in response to a shared regional climate. An ecosystem is a colony of animals and organisms in their physical environment. I also learned that parasites are organisms that feed on a host organism and causes harm to that organism. All of the organisms in an ecosystem compete for resources. There is a high competition for scarce resources. Competition for food is a common biotic factor affecting all organisms.