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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
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