ecology
the study of how organisms interact with one another and with their nonliving environment; study of connections in nature
organism
any form of life; the most fundamental unit of ecology
species
groups of organisms that resemble one another in appearance, behavior, chemistry, and genetic makeup
population
a group of interacting individuals of the same species occupying a specific area
genetic diversity
in most natural populations, individuals vary slightly in their genetic makeup, which is why they do not all look or act alike
habitat
the place where a population or individual organism normally lives is its habitat
distribution; range
the area over which we can find a species
community; biological community
consists of all the populations of different species that live and interact in a particular area
ecosystem
a community where populations of different species interact with one another and with their nonliving environment of matter and energy
biosphere
the global ecosystem where all life is interconnected; living and dead organisms
atmosphere
a thin envelope or membrane of air around the planet
troposphere
the inner layer of the atmosphere; contains the majority of the planet's air, mostly nitrogen and oxygen
stratosphere
the layer above the troposphere; contains enough ozone to filter out most of the sun's harmful UV radiation, which allows life to exist on land and in the surface layers of bodies of water
hydrosphere
consists of the earth's water; found as liquid water, ice, and water vapor
lithosphere
the earth's crust and upper mantle; contains nonrenewable fossil fuels and minerals we use as well as nutrients needed for plant life
biomes
terrestrial regions inhabited by certain types of life, especially vegetation; examples include various types of deserts, grasslands, and forests
aquatic life zones
marine and freshwater portions of the biosphere; examples include lakes, streams, estuaries, coastlines, coral reefs, and the deep ocean
abiotic
nonliving components of the ecosystem such as water, air, nutrients, and solar energy
biotic
biological components of the ecosystem such as producers, consumers, and decomposers
range of tolerance
range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally
limiting factor principle
too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance
producers; autotrophs
organisms that make their own food from compounds and energy obtained from their environment
photosynthesis
complex plants that takes place in cells of green plants; radiant energy form the sun is used to combine carbon dioxide and water to produce oxygen, carbohydrates, and other nutrient molecules
consumers; heterotrophs
organisms that get energy and nutrients they need by feeding on other organisms and their remains
primary consumers; herbivores
eat producers
secondary consumers; carnivores
feed on herbivores
third and higher level consumers
carnivores that feed on other carnivores
omnivores
feed on both plants and animals
decomposers
specialized organisms that recycle nutrients in ecosystems; secrete enzymes that digest or biodegrade living or dead organisms into simpler inorganic compounds that producers can take up from the soil and water and use as nutrients
detritivores
insects and other scavengers that feed on the wastes or dead bodies of other organisms
aerobic respiration
complex process that occurs in the cells of most living organisms, in which nutrient organic molecules such as glucose combine with oxygen to produce carbon dioxide, water, and energy
chemosynthesis
process in which certain organisms extract inorganic compounds from their environment and convert them into organic nutrient compounds without the presence of sunlight
anaerobic respiration; fermentation
form of cellular respiration in which some decomposers get the energy they need thorough the breakdown of glucose in the absence of oxygen
biological diversity; biodiversity
one of the earth's most important renewable resources; includes functional, ecological, genetic, and species diversity
HIPPO
acronym about five major causes of species decline and premature extinction; habitat destruction, invasive species, pollution, population growth, overexploitation
food chain
a sequence of organisms, each of which is a source of food for the next
trophic level
feeding level depending on whether an organism is a producer or a consumer and on what it eats or decomposes
food web
a complex network of interconnected food chains
biomass
dry weight of all organic matter contained in organisms
ecological efficiency
the percentage of usable energy transferred as biomass form one trophic level to the next
pyramid of energy flow
diagram representing the flow of energy through each trophic level in a food chain or food web; with each energy transfer, only a small part (usually 10%) of the usable energy entering one trophic level is transferred to the organisms at the next trophic
gross primary productivity (GPP)
the rate at which an ecosystem's producers convert solar energy into chemical energy a biomass
net primary productivity (NPP)
rate at which producers use photosynthesis to store energy minus the rate at which they sue some of this stored energy through aerobic respiration; amount of energy producers make
soil
thin covering over most land that is a complex mixture of eroded rock, mineral nutrients, decaying organic matter, water, air, and billions of living organisms, most of them microscopic decomposers
weathering
soil formation begins when bedrock is broken down into rock fragments and particles by physical, chemical, and biological processes
soil horizons
mature soils are arranged in a series of horizontal layers each with a distinct texture and composition that varies with different types of soils
soil profile
a cross-sectional view of the horizons in a soil
humus
partially decomposed bodies of dead plants and animals
infiltration
downward movement of water through soil
leaching
as water seeps down, it dissolves various minerals and organic matter in upper layers and carries them to lower levels
soil texture
determined by the relative amounts of the different sizes and types of mineral particles
nutrients
elements and compounds that organisms need to live, grow, and reproduce
biogeochemical cycles; nutrient cycles
nutrients move through air, water, soil, rock, and living organisms in cycles
hydrologic cycle; water cycle
collects, purifies, distributes, and recycles the earth's fixed supply of water
carbon cycle
carbon, the basic building block of the carbohydrates, fats, proteins, DNA, and other organic compounds necessary for life, circulates through the biosphere
nitrogen cycle
cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment
sulfur cycle
cyclic movement of sulfur in different chemical forms from the environment to organisms and then back to the environment
clay
smallest particle of soil
silt
medium size particles of soil
sand
large size particles of soil
layers in soil
surface litter layer --> topsoil layer --> subsoil --> parent material (bedrock)
mature soils
soils that have developed over a long time
denitrification
nitrogen leaves the soil as specialized bacteria convert ammonia and ammonium back into nitrite and nitrate ions, and then into nitrogen gas (N2) and nitrous oxide gas (N2O)
crust
soil and rock
litosphere
crust; top of upper mantle
phytoplankton
dominant producers in water; mostly microscopic organisms that float or drift in the the water
substrate
the right surface; a limiting factor
salinity
amounts of various inorganic minerals or salts dissolved in a given volume of water
phosphorus
limiting factor of marine life
nitrogen
limiting factor of terrestrial life
optimum level or range
best level of a limiting factor at which populations are the greatest
microbe
greatest biomass