History of life: o earth formed 4. 6 or 4. 5 billion years ago o 600 million years after, life emerged. Made possible by nucleic acids (dna) that store info and are able to reproduce themselves. Eukaryotic cells fail to divide and create multicellular eukaryotes. Evolutionary tree of life o demonstrates where the common ancestors of organisms are o each organism gets a binomial name (_genus_ species_) o largest branches are archaea, bacteria, eukarya. Organization within an organism: cells tissue organs organ systems organism. Organization within an environment: organism population communities landscape biosphere o population: a group of one species o communities: a group of various populations. Feedback: when a process is affected by amount of a component of the system o positive feedback: speeds the system o negative feedback: slows the system. System analysis: helps biologists understand how systems work and their specific rates o bat x time = bnow + a b b c.