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Chapter 18,19, 20

Chapters 18, 19, and 20

ecology the study of the interactions of living organisms with one another and with their environment
interdependence the dependence of every organism on its connections with other living and nonliving parts of its environment
ecological model a model that represents or describes the relationships between the componnets of an ecological system
biosphere the part of Earth where life exists; includes all of the living organisms on Earth
ecosystem a community of organisms and their abiotic environment
community a group of various species that live in the same habitat and interact with each other
population a group of organisms of the same species that live in a specific geographical area
habitat the place where an organism usually lives
biotic factor an environmental factor that is associated with or results from the activities of living organisms
abiotic factor an environmental factor that is not associated with the activities of living organisms
tolerance curve a graph of the perfomance of an organism versus the value of an environmental vairable
acclimation an organism's change in response to a change in the organism's environment
dormancy a state in which seeds, spores, bulbs, and other reproductive organs stop growth and development and reduce their metabolism, especially respiration
migration in general, any movement of individuals or populations from one location to another; specifically, a periodic group movement that is characteristic of a given population or species
niche the unique position occupied by a species, both in terms of its physical use of its habitat and its function within an ecological community
producer an organism that can make organic molecules from inorganic molecules; a photosynthetic or chemosynthetic autotroph that serves as the basic food source in an ecosystem
chemosynthesis the production of carbohydrates through the use of energy from inorganic molecules instead of light
gross primary productivity the rate at which organic matter is assimilated by plants and other producers during a period of time over a certain area
biomass plant material, manure, or any other organic matter that is used as an energy source
net primary productivity the rate at which biomass accumulates in an ecosystem
consumer an organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources
herbivore an organism that eats only plants
carnivore an organism that eats animals
omnivore an organism that eats both plants and animals
detritivore a consumer that feeds on dead plants and animals
decomposer an organism that feeds by breaking down organic matter from dead organisms; examples include bacteria and fungi
tropic level one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers
food chain the pathway of energy transfer through various stages as a result of the feeding patterns of a series of organisms
food web a diagram that shows the feeding relationships between organisms in an ecosystem
biogeochemical cycle the circulation of substances through living organisms from or to the environment
groundwater the water that is beneath Earth's surface
water cycle the continuous movement of water between the atmosphere, the land, and the oceans
transpiration the process by which plants release water vapor into the air through stomata; also the release of water vapor into the air by other organisms
carbon cycle the movement of carbon from the nonliving environment into living things and back
nitrogen cycle the cycling of nitrogen between organisms, soil, water, and the atmosphere
nitrogen fixation the process by which gaseous nitrogen is converted into ammonia, a compound that organisms can use to make amino acids and other nitrogen-containing organic molecules
nitrogen-fixing bacteria bacteria that convert atmospheric nitrogen into ammonia
ammonification the formation of ammonia compounds in the soil by the action of bacteria on decaying matter
nitrification the process by which nitrites and nitrates are produced by bacteria in the soil
denitrification the liberation of nitrogen from nitrogen-containing compounds by bacteria in the soil
phosphorus cycles the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment
population a group of organisms of the same species that live in a specific geographical area
population density the number of individuals of the same species that live in a given unit of area
dispersion in ecology, the pattern of distribution of organisms in a population
birth rate the number of births that occur in a period of time in a given area
death rate the number of deaths occurring in a period of time
life expectancy the average length of time that an individual is expected to live
age structure the classification of members of a population into groups according to age or the distribution of members of a population in terms of age groups
survivorship curve the percentage of newborn individuals in a population that can be expected to survive to a given age
growth rate an expression of the increase in the size of an organism or population over a given period of time
immigration the movement of an individual or a group to a new community or region
emidration the movement of an individual or group out of its native area
exponential model a model of population growth in which a constant and unlimited growth rate results in geometric increases in population size
limiting factor an environmental factor that prevents an organism or population from reaching its full potential of distribution or activity
logistic model a model of population growth that assumes that finite resource levels limit population growth
carrying capacity the largest population that an environment can support at any given time
density-independent factor a variable that affects a population regardless of the population density, such as climate
density-dependent factor a variable affected by the number of organisms present in a given area
inbreeding the crossing or mating of plants or animals with close relatives
hunter-gatherer lifestyle a way of life in which people obtain their food by hunting and gathering wild animals and plants
agricultural revolution the change from a hunting and gathering society to an agricultural society that began about 10,000 years ago
developed country a modern, industrialized country in which people are generally better educated and healthier and live longer than people in developing countries do
developing country a country in which the society is less modern and less industrialized and in which inhabitants are generally poorer than they are in developed countries
demographic transition the general pattern of demographic change from high birth and death rates to low birth and death rates, as observed in the history of more-developed countries
predation an interaction between two organisms in which one organism, the predator, kills and feeds on the other organism, the prey
inter-specific competition a relationship between two species in which both species compete for limited resources such that both species are negatively affected by the relationship
symbiosis a relationship in which two different organisms live in close association with each other
parasitism a relationship between two species in which one species, the parasite, benefits from the other species, the host, which is harmed
mutualism a relationship between two species in which both species benefit
commensalism a relationship between two organisms in which one organism benefits and the other is unaffected
species richness the number of different species in an area or community
species evenness a measure of the relative adundance of each species in an ecological community
species-area effect a pattern in which the number of species in an area increases as the area increases
disturbance in ecology, an event that changes a community by removing or destroying organisms or altering resource availability
stability the tendency of a community to maintain a relatively constant structure
ecological succession a gradual process of change and replacement in a community
primary succession succession that begins in an area that previously did not support life
secondary succession the process by which one community replaces another community that has been partially or totally destroyed
pioneer species a species that colonizes an uninhabited area and that starts an ecological cycle in which many other species become established
climax community a final, stable community in equilibrium with the environment
Created by: WillReese2



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