59 terms


a group of individuals of one species living in one area who can interbreed and interact with each other
all the organisms living in one area
all the organisms in a given area and the abiotic factors with which they interact
abiotic factors
nonliving environmental factors (e.g. temperature, water, sunlight, wind, rocks, and soil)
biotic factors
all the organisms with which an organism might react
the global ecosystem
the total number of individuals in a population
births, deaths, immigration, and emigration affect the size of this
the number of individuals per unit area or volume
definied by its size, density, and dispersion
the pattern of spacing of individuals within the area the population inhabits
the most common pattern of dispersal
biotic potential
the maximum rate at which a population could increase under ideal conditions
carrying capacity
limit to then umber of individuals that can occupy one area at a particular time
exponential growth
a population with no predation, parasitism, or competition, no immigration or emigration, and in an environment with unlimited resources
exponential growth
characteristic of a popultion that has been recently introduced into an area
reproduce rapidly when the environment is uncrowded and resources are vast
maximize population size near the carrying capacity for an environment
limiting factors
factors that limit population growth; divided into: density-dependent and density independent factors
density-dependent factors
factors that increase directly as the population density increases (e.g. competition, predation, disease)
density-independent factors
factors whose occurence is unrelated to the population density (e.g. natural disasters)
symbiotic relationship where both organisms benefit
symbiotic relationship in which one organism benefits and one is not affected
symbiotic relationship where one organisms benefits while the other is harmed
food chain
the pathway along which food is transferred from one trophic level to another
food web
interwoven food chains
convert light energy into chemical energy and have the greatest biomass of any trophic level
only about ___% of the energy stored in any trophic level is converted to organic matter at the next trophic level
gross primary productivity
the amount of energy converted to chemical energy by photosynthesis per unit time in an ecosystem
net primary productivity
the gross primary productivity minus the energy used by the primary producers for respiration
biological magnification
organisms at higher trophic levels have greater concentrations of accumulated toxins stored in their bodies than those at lower trophic levels
nutrients would not be recycled back to the soil to nourish plants, and there would be no food chain and no life without these
bacteria and fungi
ecological succession
the rebuilding of an ecosystem after either natural or man-made destruction
primary ecological succession
the rebuilding of an ecosystem in a lifeless area where soil has been removed
soil building
the essential and dominant characteristic of primary ecological succession
pioneer organisms
the first organisms to inhabit a barren area after an ecosystem is destroyed
secondary ecological succession
when an existing community has been cleared by some disturbance that leaves the soil intact
large regions of Earth whose distribution depends on the amountof rainfall and the temperature in an area
each characterized by different vegetation and animal life
largest biome on Earth, covering 3/4 of the Earth's surface
most stable biome
biome that provides most of Earth's food and oxygen
tropical rainforest
biome that has the greatest diversity of animal species
tropical rainforest
biome that accounts for more than 20% of Earth's net carbon fixation (food production)
biome with the most extreme fluctuations in temperature of any biome
largest terrestrial biome
conifer forest
carbon cycle
the basis of this is photosynthesis and respiration
most nitrogen enters ecosystems by this
nitrogen-fixing bacteria
live in the nodules of the roots of legumes and convert free nitrogen into ammonium
nitrifying bacteria
convert ammonium into nitrites and then into nitrates
denitrifying bacteria
convert nitrates into free atmospheric nitrogen
depletion of oxygen in water because of increase of nutrients that cause eccessive growth of oxygen-depleting plants
organic material accumulates on the bottom of a lake body and reduces the depth of the lake
detritivores use up oxygen as they decompose the dead organic matter; the depletion of oxygen makes it impossible for other organisms to live
greenhouse effect
increased concentration of carbon dioxide in the air; carbon dioxide and water vapor in the air absorb much of the infared radiation reflect off the Earth
global warming
the increase in temperature due to the greenhouse effect
chemical used for refrigerators and aerosols that have caused the formation of a hole in the oxone layer, allowing more UV light to reach Earth