Structure of dna (cid:159) mitosis & meiosis (cid:159) Small questions: answering small tractable questions can help contribute towards solving a big question. Large question: unlikely to be answered by one experiment; required multiple lines of evidence (ex. How questions: involve determine the physiological or genetic mechanisms responsible for aspects of a trait. Why question: involve determine the ecological function and adaptive significance of a trait. Approaches used in evolutionary biology (cid:159) observational: describe and quantify (cid:159) (cid:159) (cid:159) Experimental: manipulate a system to address a specific hypothesis; requires an experimental design and statistical analysis. Important assumptions about evolution verified by scientific study (cid:159) organisms on earth have changed through time (cid:159) (cid:159) (cid:159) (cid:159) most evolutionary change results from natural selection. Lineages split or branch by speciation resulting in the generation of biodiversity. Biodiversity: the variety of life on earth; the number and kinds of living organisms in a given area.