bio 1114

the hadean
Click the card to flip 👆
1 / 29
Terms in this set (29)
-early organisms had methane based metabolism
-producing co2 and alcohol as by-products
-photosynthetic organisms appear
-respired o2 accumulates and strengthens the ozone layer trapping free oxygen below
-atmosphere is converted to an oxygen environment
-earliest life most likely consisted of prokaryotic bacteria like organisms
-eukaryotic cells evolved when aerobic bacteria either infected or were engulfed by a larger host cell and later established a symbiotic relationship
-mitochondria- thought to have derived from purple bacteria
-chloroplasts- thought to have derived from cyanobacteria

-circular genomes in chloroplasts, mitochondria and bacteria
-mitochondria have cell membranes v. similar to prokaryotes
-need for support and rigidity increases
-reproduction becomes more difficult
-suface area- volume ration (S/V) goes down
-as size increases (SA) controls exchange with environment (diffusion, heat exchange)
-metabolic chemicals largely depend on V
-animals adjust S/V by shape, use bulk transport to supplement diffusion for long-distant movement of materials
opportunities of multicellularity-cellular and tissue specialization (greater complexity) becomes possible -distinct reproductive organs, tissues, cells -specialization and compartmentalization -skeleton for support/movement -epidermal layer to keep interior from drying and protection -vascular system- transportationCambrian explosion- relatively sudden appearance of diverse animal forms in fossil record -fossils of many phyla appear in the early cambrian -represented by several "lagerstatten" where soft bodied animals have been preserved -by the end all "major" phyla were present explanations -intrinsic -extrinsicintrinsicCambrian Explosion explanation -something about animals changed (ex: new development patterns) explanation: -hox and hoc-like genes were duplicated in the bilaterians -the number of such genes correlated with complexityextrinsicCambrian explosion- explanation -something about the environment changed (ex: increase in availability of oxygen) explanation: -ancient atmosphere contained insufficient o2 to allow evolution of active life stylesevolution of land plants... what 2 kinds-red algae (5,000 species) -green algae (8,000 species) (both unicellular or multicellular)characteristics of land plants-multicellular or non-motile -cell walls with cellulose -apical meristems -autotrophic -alternation of generations (gametophyte)atrophyresulting from primary endosymbiosis with cyanobacteriacell wall-touch, often flexible layer surrounding the cell membrane -helps prevent cell rupture - in plants, cellulose fibers in pectin matrixapical meristemsregions of rapid cell division (mitosis) and differentiation found both roots and shootsgametophyte-the haploid multicellular stage in the alternation of generations -life cycle of plants and algaesporophyte-the asexual and usually diploid phase -producing spores from which the gametophyte arisesorganisms transitioning to land faced several key challenges-avoiding desiccation while undergoing gas exchange -obtaining key minerals -reproducing in the absence of water -structural support without buoyancykey adaptions for vascular plants...1. vascular tissues (xylem, phloem) 2. Leaves 3. sporophylls 4. secondary growthxylemreinforced hollow pipes for transporting water and inorganic nutrients - water and nutrient transportphloem-sugar transportcarboniferousseedless vascular plants dominated the landscapeseeds-gametophytes surrounded by sporophyte tissue -no external water needed for reproductiongymnospermsnaked seedsconifers-most diverse -many adapted to dry conditions -needle like leaves are common