Case 4 Genetic drift a change in gene pool that occurs purely as a result of chance Replica plating so whatever is tested have the same position on each petri dish genetic drift has a strong effect when the population is too small As antibiotic concentrations increased the number of colonies decreased in Case 3 Heterozygote Advantage Population size 10 000 Fitness values AA 0 95 Aa 1 0 Aa 0 90 A a 0 0 a A 0 0 Mutation rate Initial allele frequency 0 5 Number of generations 1 000 Population size 100 Fitness values AA 1 0 Aa 1 0 Aa 1 0 Mutation rate A a 0 0 a A 0 0 Initial allele frequency 0 5 Number of generations 500 o E coli quantity and size Ecology Ecosystem the total sum of interacting living organisms and their non living environment in a determined area Ecology the interdisciplinary scientific study of organisms and their interactions with their environment Population ecology is a major sub field of ecology that deals with the dynamics of species populations and how these populations interact with the environment Population ecology includes the study of the distribution and abundance of a population of a given species in a specified area at a specified time Community ecology a subdiscipline of ecology which studies the distribution abundance demography and interactions between coexisting populations Biotic factors factors created by a living thing or any living component within an environment in which the action of the organism affects the life of another organism o Predators o Parasites o Disease o Competitors Competition occurs whenever two or more organisms need the same resources AND these resources are in limited supply o Mates o Density dependent factors Abiotic factors nonliving components of the biosphere o Chemical and geological factors o Rocks and minerals o Temperature o Weather o Density independent factors Carrying capacity the maximum amount of living organism that inhabit a certain place determined by the limiting factor s Chlamydomonas reinhardtii o Green algae o Unicellular o Flagellated o Model organisms for molecular biology especially studies of flagellar motility and chloroplast dynamics biogenesis and genetics o Optimal growth at 23 C o Light attracted organelles Autotrophs or producer is an organism that produces complex organic compounds such as carbohydrates fats and proteins from simple substances present in its surroundings generally using energy from light photosynthesis or inorganic chemical reactions chemosynthesis They are the producers in a food chain such as plants on land or algae in water in contrast to heterotrophs as consumers of autotrophs Heterotrophs an organism that cannot fix carbon and uses organic carbon for growth Heterotrophs can be further divided based on how they obtain energy if the heterotroph uses light for energy then it is considered a photoheterotroph while if the heterotroph uses inorganic organic energy sources it is considered a chemoheterotroph Nitrogen cycle the process by which nitrogen is converted between its various chemical forms Largest pool is N2 in the atmosphere which is not biologically useful Biological pool in soil where organisms convert N2 into a usable form Biological Organism driven cycle or timescale amino acids proteins nucleic acids nitrate NO3 nitrite NO2 ammonia NH3 component of fertilizers found in runoff