the scientific study of interactions among organisms and between organisms and their environment or surroundings (ecosystems).
anywhere on Earth where life exists
a group of ecosystems that have the same climate and similar dominant communities
a collection of the organisms that life in a particular place and their nonliving environment
all of the different populations that live together in a defined area
group of individuals that belong to the same species and live in the same area
a group of organisms that are similar and can breed and produce fertile offspring
one single member of a species
organisms that can capture energy from sunlight or chemicals and use that energy to produce food; also known as producers.
process used by most autotrophs; creates food and oxygen from sunlight, carbon dioxide and water.
process used by some autotrophs; creates food from carbon dioxide and inorganic molecules without light.
organisms that rely on other organisms for their energy and food supply; also known as consumers
eat only plants
eat only animals
eat both plants and animals
feed on dead plants and animals (detritus)
break down organic matter
a series of steps in which organisms transfer energy by eating and being eaten
a diagram that links all the food chains in an ecosystem together to form a more realistic view of energy flow
each step in a food chain or food web
a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or web. Three main types of pyramids are:
shows the relative amount of energy available at each trophic level.
shows the total amount of living tissue within a given trophic level
Pyramid of numbers
shows the relative number of individual organisms at each trophic level
how elements, chemical compounds, and water are passed from one organism to another and from one part of the biosphere to another
when liquid water absorbs energy and becomes a gas
when water falls from the sky as rain, snow, sleet, or hail
when water is given off through the stomata of plants' leaves as a byproduct of photosynthesis
when gaseous water vapor loses energy and becomes a liquid
when precipitation travels along the surface of the Earth until it reaches a body of water
the rate at which organic matter is created by producers
a single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem
the sudden growth of algae in a body of water
the area inhabited by a population
the number of individuals per unit area
determined by the number of births, the number of deaths, and the number of individuals that enter or leave the population
the movement of individuals into an area
the movement of individuals out of an area
the type of growth seen when a population grows at a constant rate; represented by a "J"-shaped curve
when a population's growth slows or stops following a period of exponential growth; represented by an "S"-shaped curve
the largest number of individuals that a given environment can support
a factor that causes population growth to decrease; ex. climate, predators, food availability, or humans.
Density-dependent limiting factor
limiting factors that effect a population only when the population density reaches a certain level and operate most strongly when a population is large.
occurs when two organisms attempt to use the same resource; can occur between organisms or between species
when one species eats another for food; one of the best forms of natural population control.
Density-independent limiting factors
limiting factors that affect all populations in similar ways, regardless of the population size.
the study of human populations
the change in a population from high birth and death rates to low birth and death rates
models that help demographers predict future growth of populations by showing the number of individuals in each age category
The process of using mathematical formulas to predict future events