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ECOLOGY Date: 3-1: Populations (p.118) *Ecology: study of interactions among organisms & btwn organisms & their env Organization (fig 3-2) A. Individual (species) B. Population C. Community D. Ecosystem – all the organisms in an area together w/ nonliving (physical) env E. Biome F. Biosphere – portions of planet in which life exists, including land, water, atmosphere Date: 3-2: Energy Flow (p.67) Producers sunlight is the main E source for life < 1% is used autotrophs: use sunlight or chemical E to produce food (aka, producers) assemble organic molecules from inorganic compounds photosynthesis: use of solar E to convert CO2 & H2O into O2 & CHO (fig 3-5) chemosynthesis: use chemical E to produce CHO (bacteria) (fig 3-6) Consumers heterotrophs (consumers) rely on other organisms for food & E a) herbivores b) carnivores c) omnivores d) detritivores – feed on dead matter called detritus (mites, earthworms, snails, crabs) e) decomposers – break down organic matter (bacteria, fungi) Date: Feeding Relationships (p.69) *Energy flows in ONE direction, starting w/ sun & inorganic cmpds food chain: organisms transfer E by eating & being eaten (fig 3-7) food web: network of interactions that links food chains (fig 3-8) trophic level: each step in a food chain/web Ecological Pyramids – diagram that shows relative amounts of E or matter w/in each trophic level (fig 3-9) 1. energy pyramid – only 10% of energy is transferred to next trophic level most is used for life processes (respiration, movement, reproduction) or released as heat 2. biomass pyramid biomass: total amount of living tissue in a trophic level 3. pyramid of numbers – based on number of organisms Date: 3-3: Cycles of Matter (p. 74) *95% of body is made of O, C, H, & N *unlike E, matter is recycled Water Cycle (fig 3-11) water enters atmosphere by: a. evaporation – process of water Δ’ing from liquid to gas (water vapor) b. transpiration – evaporation of water thru leaves clouds form precipitation Nutrient Cycles * nutrients: chemical substances an organism needs to build tissues & carry out essential life fxns A. carbon cycle (fig 3-13) – C stored in: air as CO2 & methane (CH4) oceans as dissolved CO2 land as fossil fuels & rocks B. nitrogen cycle (N used to build AA) (fig 3-14) nitrogen fixation – convert nitrogen gas (N2) into ammonia (NH3) denitrification – convert nitrates (NO2, NO3) into N2 C. phosphorus cycle (DNA & RNA) P does not enter atmosphere; remains on land & in ocean sediments as phosphate Nutrient Limitation (p.80) * limiting nutrients limit growth of organisms in an ecosystem in oceans nitrogen in freshwater env. phosphorus algal bloom can result from excess of limiting nutrient Date: 4-2: Ecosystems *biotic factors: biological (living) factors *abiotic “ ”: physical (nonliving) factors *niche: all biotic & abiotic factors affecting an organism & the way an organism uses them includes place in food web, temp., & mating strategies 4-3: Biomes * tropical rain forests have greatest biodiversity Date: 5-1: How Populations Grow (p.118) * geographic distribution (range) – area inhabited * population density - # of ind per unit area Population Growth – affected by: 1) # of births 2) # of deaths 3) immigration vs. emigration immigration: movement of ind into an area emigration: “ ” out of an area Exponential Growth – occurs when ind in pop reproduce at a constant rate J-shaped curve (fig 5-3) * under ideal conditions, pop will grow exponentially Logistic Growth – pop growth slows or stops following period of exp. growth S-shaped curve (fig 5-4) results from resources becoming scarce carrying capacity: largest # of ind a given env can support Date: 5-2: Limits to Growth (p.124) *limiting factor: causes pop growth to ↓ (fig 5-5) density-dependent factors: depend on pop size become limiting when pop density reaches certain level o competition (food, water, space, sunlight) o predation predator-prey relationship (fig 5-7) o parasitism & disease density-independent factors: affect pop regardless of size o abnormal weather, natural disasters, human act. Date: 5-3: Human Population Growth (p.129) *human pop has grown exponentially since Industrial Revolution (fig 5-10) Patterns of Growth demography: scientific study of human populations the demographic transition: dramatic drop in death rate followed by birth rate (fig 5-12) USA, Japan, Europe age-structure diagrams (pop profiles): used to predict pop growth (fig 5-13) Future Pop. Growth (fig 5-14) *depends on age structure of each country, prevalence of life-threatening diseases *** Study your CH 6 Study Guide! ***